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  • mailto: anchor links unloading html5 video in Chrome

    - by Robin Pyon
    I have a very simple page with a <video> tag and an email anchor link: http://jsfiddle.net/6GquX/3/ Clicking the email link in Chrome (OS X 10.8 + Win7, 23.0.1271.97) invokes the beforeunloadchange event and causes the video to unload, which isn't the desired outcome. Curiously enough, if I let the video buffer a bit and then click the email link, the video keeps playing and doesn't unload. To my knowledge this only occurs in Chrome and I'm truly at a loss. Visiting any HTML5 video player site (videojs, flowplayer etc), starting a HTML5 video and then immediately simulating an email click with document.location.href = "mailto:[email protected]" in the dev console yields the same error. However, I'm inclined to think it's the way in which the video has been encoded as I'm unable to recreate the above with a video downloaded from YouTube's HTML5 player: http://jsfiddle.net/6GquX/4/ (source) 1. Is it possible that YouTube are encoding their videos in a particular way to combat this? 2. Are there any strategies / hacks I can employ to get around this?

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  • Deduping your redundancies

    - by nospam(at)example.com (Joerg Moellenkamp)
    Robin Harris of Storagemojo pointed to an interesting article about about deduplication and it's impact to the resiliency of your data against data corruption on ACM Queue. The problem in short: A considerable number of filesystems store important metadata at multiple locations. For example the ZFS rootblock is copied to three locations. Other filesystems have similar provisions to protect their metadata. However you can easily proof, that the rootblock pointer in the uberblock of ZFS for example is pointing to blocks with absolutely equal content in all three locatition (with zdb -uu and zdb -r). It has to be that way, because they are protected by the same checksum. A number of devices offer block level dedup, either as an option or as part of their inner workings. However when you store three identical blocks on them and the devices does block level dedup internally, the device may just deduplicated your redundant metadata to a block stored just once that is stored on the non-voilatile storage. When this block is corrupted, you have essentially three corrupted copies. Three hit with one bullet. This is indeed an interesting problem: A device doing deduplication doesn't know if a block is important or just a datablock. This is the reason why I like deduplication like it's done in ZFS. It's an integrated part and so important parts don't get deduplicated away. A disk accessed by a block level interface doesn't know anything about the importance of a block. A metadata block is nothing different to it's inner mechanism than a normal data block because there is no way to tell that this is important and that those redundancies aren't allowed to fall prey to some clever deduplication mechanism. Robin talks about this in regard of the Sandforce disk controllers who use a kind of dedup to reduce some of the nasty effects of writing data to flash, but the problem is much broader. However this is relevant whenever you are using a device with block level deduplication. It's just the point that you have to activate it for most implementation by command, whereas certain devices do this by default or by design and you don't know about it. However I'm not perfectly sure about that ? given that storage administration and server administration are often different groups with different business objectives I would ask your storage guys if they have activated dedup without telling somebody elase on their boxes in order to speak less often with the storage sales rep. The problem is even more interesting with ZFS. You may use ditto blocks to protect important data to store multiple copies of data in the pool to increase redundancy, even when your pool just consists out of one disk or just a striped set of disk. However when your device is doing dedup internally it may remove your redundancy before it hits the nonvolatile storage. You've won nothing. Just spend your disk quota on the the LUNs in the SAN and you make your disk admin happy because of the good dedup ratio However you can just fall in this specific "deduped ditto block"trap when your pool just consists out of a single device, because ZFS writes ditto blocks on different disks, when there is more than just one disk. Yet another reason why you should spend some extra-thought when putting your zpool on a single LUN, especially when the LUN is sliced and dices out of a large heap of storage devices by a storage controller. However I have one problem with the articles and their specific mention of ZFS: You can just hit by this problem when you are using the deduplicating device for the pool. However in the specifically mentioned case of SSD this isn't the usecase. Most implementations of SSD in conjunction with ZFS are hybrid storage pools and so rotating rust disk is used as pool and SSD are used as L2ARC/sZIL. And there it simply doesn't matter: When you really have to resort to the sZIL (your system went down, it doesn't matter of one block or several blocks are corrupt, you have to fail back to the last known good transaction group the device. On the other side, when a block in L2ARC is corrupt, you simply read it from the pool and in HSP implementations this is the already mentioned rust. In conjunction with ZFS this is more interesting when using a storage array, that is capable to do dedup and where you use LUNs for your pool. However as mentioned before, on those devices it's a user made decision to do so, and so it's less probable that you deduplicating your redundancies. Other filesystems lacking acapability similar to hybrid storage pools are more "haunted" by this problem of SSD using dedup-like mechanisms internally, because those filesystem really store the data on the the SSD instead of using it just as accelerating devices. However at the end Robin is correct: It's jet another point why protecting your data by creating redundancies by dispersing it several disks (by mirror or parity RAIDs) is really important. No dedup mechanism inside a device can dedup away your redundancy when you write it to a totally different and indepenent device.

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  • Squid server - multiple originservers with different domains

    - by jduncan
    I have 2 squid servers load-balanced with F5 LTMs set up as a reverse proxy. My problem: origin server A hosts domains 1, 2, and 3 origin server B hosts domains 4 and 5. how can I set up squid so that it will cache all vhosts for both servers? my current config: cache_peer serverA parent 80 0 round-robin no-query originserver login=PASS If I add a second line: cache_peer serverB parent 80 0 round-robin no-query originserver login=PASS it only caches domains on serverB, requests for serverA content generate 404 errors. I don't use squid a whole lot, and all help is appreciated. thanks.

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  • Slow login to load-balanced Terminal Server 2008 behind Gateway Server

    - by Frans
    I have a small load-balanced (using Session Broker) Terminal Server 2008 farm behind a Gateway Server which is accessed from the Internet. The problem I have is that there is a delay of 20-30 seconds if the session broker switches the user to another server during login. I think this is related to the fact that I am forcing the security layer to be RDP rather than SSL. The background The Gateway server has a public routeable IP addres and DNS name so it can be accessed from the Internet and all users come in via this route (the system is used to provide access to hosted applications to external customers). The actual terminal servers only have internal IP addresses. This works really well, except that with a Vista or Windows 7 client, the Remote Desktop client will negotiate with the server to use SSL for the security layer. This then exposes the auto-generated certificate that TS1 or TS2 has - but since they are internal, auto-generated certificates, the client will get a stern warning that the certificate is not valid. I can't give the servers a properly authorised certificate as the servers do not have public routeable IP address or DNS name. Instead, I am using Group Policy to force the connections to be over RDP instead of SSL. \Computer Configuration\Policies\Administrative Templates\Windows Components\Terminal Services\Terminal Server\Security\Require use of specific security layer for remote (RDP) connections The Windows 7 user now gets a much less stern warning that "the server's identity cannot be confirmed" which I can live with. I don't have enough control over the end-user's machines to ask them to install a new root certificate either. TS1 and TS2 are also load-balanced using the Session Broker, which is installed on the Gateway Server. I am using round-robin DNS, so the user's initial connection will go via Gateway1 to either TS1 or TS2. TS1/TS2 will then talk to the session broker and may pass the user to the other server. I.e. the user may get connected to TS2, but after talking to the session broker the user may be passed to TS1, which is where they will run their session. When this switching of servers happens, in my setup, the screen sits with the word "Welcome" for 20-30 seconds after which it flickers, Welcome is shown again and then flashing through nthe normal login screens (i.e. "wait for user profile manager" etc). Having done some research, I think what is happening is that the user is being fully logged on to TS2 (while "Welcome" is shown) before being passed to TS1, where they are then logged in again. It is interesting that normally when you see the ""Welcome" word, the little circle to left rotates. However, it does not rotate during this delay - the screen just looks frozen. This blog post leads me to think that this is because CredSSP is not being used, probably because I am disallowing SSL and forcing RDP. What I have tried I enabled SSL again which removes the "Welcome" delay. However, it seems to introduc a new delay much earlier in the process. Specifically, when the RDP client is saying "initialising connection" - this is now much slower. Quite apart from the fact that my certificate problem precludes me using that solution without considerable difficulty. I tried disabling the load balancing (just remove the servers from the session broker farm) and the connections do not have any delay. The problem is also intermittent in the sense that it only happens when the user gets bumped from one server to another. I tested this by trying to connect directly to TS1 (via the Gateway, of course) and then checking which server I actually got connected to. Just to be sure, I also by-passed the round-robin DNS to see if it had any impact and it doesn't. The setup is essentially in line with MS recommendations here: TS Session Broker Load Balancing Step-by-Step Guide I tried changing to using a dedicated redirector. Basically, rather than using a round-robin DNS, I pointed my DNS to the Gateway server and configured it to be a dedicated redirector (disallow logons, add it to the farm). Same problem, alas. Any ideas or suggestions gratefully received.

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  • How do you re-mount an ext3 fs readwrite after it gets mounted readonly from a disk error?

    - by cagenut
    Its a relatively common problem when something goes wrong in a SAN for ext3 to detect the disk write errors and remount the filesystem read-only. Thats all well and good, only when the SAN is fixed I can't figure out how to re-re-mount the filesystem read-write without rebooting. Behold: [root@localhost ~]# multipath -ll mpath0 (36001f93000a310000299000200000000) dm-2 XIOTECH,ISE1400 [size=1.1T][features=1 queue_if_no_path][hwhandler=0][rw] \_ round-robin 0 [prio=2][active] \_ 1:0:0:1 sdb 8:16 [active][ready] \_ 2:0:0:1 sdc 8:32 [active][ready] [root@localhost ~]# mount /dev/mapper/mpath0 /mnt/foo [root@localhost ~]# touch /mnt/foo/blah All good, now I yank the LUN out from under it. [root@localhost ~]# touch /mnt/foo/blah [root@localhost ~]# touch /mnt/foo/blah touch: cannot touch `/mnt/foo/blah': Read-only file system [root@localhost ~]# tail /var/log/messages Mar 18 13:17:33 localhost multipathd: sdb: tur checker reports path is down Mar 18 13:17:34 localhost multipathd: sdc: tur checker reports path is down Mar 18 13:17:35 localhost kernel: Aborting journal on device dm-2. Mar 18 13:17:35 localhost kernel: Buffer I/O error on device dm-2, logical block 1545 Mar 18 13:17:35 localhost kernel: lost page write due to I/O error on dm-2 Mar 18 13:17:36 localhost kernel: ext3_abort called. Mar 18 13:17:36 localhost kernel: EXT3-fs error (device dm-2): ext3_journal_start_sb: Detected aborted journal Mar 18 13:17:36 localhost kernel: Remounting filesystem read-only It only thinks its read-only, in reality its not even there. [root@localhost ~]# multipath -ll sdb: checker msg is "tur checker reports path is down" sdc: checker msg is "tur checker reports path is down" mpath0 (36001f93000a310000299000200000000) dm-2 XIOTECH,ISE1400 [size=1.1T][features=0][hwhandler=0][rw] \_ round-robin 0 [prio=0][enabled] \_ 1:0:0:1 sdb 8:16 [failed][faulty] \_ 2:0:0:1 sdc 8:32 [failed][faulty] [root@localhost ~]# ll /mnt/foo/ ls: reading directory /mnt/foo/: Input/output error total 20 -rw-r--r-- 1 root root 0 Mar 18 13:11 bar How it still remembers that 'bar' file being there... mystery, but not important right now. Now I re-present the LUN: [root@localhost ~]# tail /var/log/messages Mar 18 13:23:58 localhost multipathd: sdb: tur checker reports path is up Mar 18 13:23:58 localhost multipathd: 8:16: reinstated Mar 18 13:23:58 localhost multipathd: mpath0: queue_if_no_path enabled Mar 18 13:23:58 localhost multipathd: mpath0: Recovered to normal mode Mar 18 13:23:58 localhost multipathd: mpath0: remaining active paths: 1 Mar 18 13:23:58 localhost multipathd: dm-2: add map (uevent) Mar 18 13:23:58 localhost multipathd: dm-2: devmap already registered Mar 18 13:23:59 localhost multipathd: sdc: tur checker reports path is up Mar 18 13:23:59 localhost multipathd: 8:32: reinstated Mar 18 13:23:59 localhost multipathd: mpath0: remaining active paths: 2 Mar 18 13:23:59 localhost multipathd: dm-2: add map (uevent) Mar 18 13:23:59 localhost multipathd: dm-2: devmap already registered [root@localhost ~]# multipath -ll mpath0 (36001f93000a310000299000200000000) dm-2 XIOTECH,ISE1400 [size=1.1T][features=1 queue_if_no_path][hwhandler=0][rw] \_ round-robin 0 [prio=2][enabled] \_ 1:0:0:1 sdb 8:16 [active][ready] \_ 2:0:0:1 sdc 8:32 [active][ready] Great right? It says [rw] right there. Not so fast: [root@localhost ~]# touch /mnt/foo/blah touch: cannot touch `/mnt/foo/blah': Read-only file system OK, doesn't do it automatically, I'll just give it a little push: [root@localhost ~]# mount -o remount /mnt/foo mount: block device /dev/mapper/mpath0 is write-protected, mounting read-only Noooooooooo. I have tried all sorts of different mount/tune2fs/dmsetup commands and I cannot figure out how to get it to un-flag the block device as write-protected. Rebooting will fix it, but I'd much rather do it on-line. An hour of googling has gotten me nowhere either. Save me ServerFault.

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  • Number crunching algo for learning multithreading?

    - by Austin Henley
    I have never really implemented anything dealing with threads; my only experience with them is reading about them in my undergrad. So I want to change that by writing a program that does some number crunching, but splits it up into several threads. My first ideas for this hopefully simple multithreaded program were: Beal's Conjecture brute force based on my SO question. Bailey-Borwein-Plouffe formula for calculating Pi. Prime number brute force search As you can see I have an interest in math and thought it would be fun to incorporate it into this, rather than coding something such as a server which wouldn't be nearly as fun! But the 3 ideas don't seem very appealing and I have already done some work on them in the past so I was curious if anyone had any ideas in the same spirit as these 3 that I could implement?

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  • Today is my first day in the land of backbone.js

    - by Andrew Siemer - www.andrewsiemer.com
    I am semi-excited to say that today is my first day into the land of backbone.js.  This will of course take me into many other new javascript-y areas.  As I have primarily been focused on building backend systems for the past many years…with no focus on client side bits…this will be all new ground for me.  Very exciting! I am sure that this endeavor will lead to writing about many new findings along the way.  Expect the subject of near future postings to not be related to MVC or server side code. I am starting this journey by reading through the online book “Backbone Fundamentals”.  http://addyosmani.com/blog/backbone-fundamentals/  Has anyone read this yet?  Any feed back on that title. I have read though Derrick Bailey’s thoughts here and here…also very good. Any suggestions on other nuggets of learning backbone?

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  • How do you re-mount an ext3 fs readwrite after it gets mounted readonly from a disk error?

    - by cagenut
    Its a relatively common problem when something goes wrong in a SAN for ext3 to detect the disk write errors and remount the filesystem read-only. Thats all well and good, only when the SAN is fixed I can't figure out how to re-re-mount the filesystem read-write without rebooting. Behold: [root@localhost ~]# multipath -ll mpath0 (36001f93000a310000299000200000000) dm-2 XIOTECH,ISE1400 [size=1.1T][features=1 queue_if_no_path][hwhandler=0][rw] \_ round-robin 0 [prio=2][active] \_ 1:0:0:1 sdb 8:16 [active][ready] \_ 2:0:0:1 sdc 8:32 [active][ready] [root@localhost ~]# mount /dev/mapper/mpath0 /mnt/foo [root@localhost ~]# touch /mnt/foo/blah All good, now I yank the LUN out from under it. [root@localhost ~]# touch /mnt/foo/blah [root@localhost ~]# touch /mnt/foo/blah touch: cannot touch `/mnt/foo/blah': Read-only file system [root@localhost ~]# tail /var/log/messages Mar 18 13:17:33 localhost multipathd: sdb: tur checker reports path is down Mar 18 13:17:34 localhost multipathd: sdc: tur checker reports path is down Mar 18 13:17:35 localhost kernel: Aborting journal on device dm-2. Mar 18 13:17:35 localhost kernel: Buffer I/O error on device dm-2, logical block 1545 Mar 18 13:17:35 localhost kernel: lost page write due to I/O error on dm-2 Mar 18 13:17:36 localhost kernel: ext3_abort called. Mar 18 13:17:36 localhost kernel: EXT3-fs error (device dm-2): ext3_journal_start_sb: Detected aborted journal Mar 18 13:17:36 localhost kernel: Remounting filesystem read-only It only thinks its read-only, in reality its not even there. [root@localhost ~]# multipath -ll sdb: checker msg is "tur checker reports path is down" sdc: checker msg is "tur checker reports path is down" mpath0 (36001f93000a310000299000200000000) dm-2 XIOTECH,ISE1400 [size=1.1T][features=0][hwhandler=0][rw] \_ round-robin 0 [prio=0][enabled] \_ 1:0:0:1 sdb 8:16 [failed][faulty] \_ 2:0:0:1 sdc 8:32 [failed][faulty] [root@localhost ~]# ll /mnt/foo/ ls: reading directory /mnt/foo/: Input/output error total 20 -rw-r--r-- 1 root root 0 Mar 18 13:11 bar How it still remembers that 'bar' file being there... mystery, but not important right now. Now I re-present the LUN: [root@localhost ~]# tail /var/log/messages Mar 18 13:23:58 localhost multipathd: sdb: tur checker reports path is up Mar 18 13:23:58 localhost multipathd: 8:16: reinstated Mar 18 13:23:58 localhost multipathd: mpath0: queue_if_no_path enabled Mar 18 13:23:58 localhost multipathd: mpath0: Recovered to normal mode Mar 18 13:23:58 localhost multipathd: mpath0: remaining active paths: 1 Mar 18 13:23:58 localhost multipathd: dm-2: add map (uevent) Mar 18 13:23:58 localhost multipathd: dm-2: devmap already registered Mar 18 13:23:59 localhost multipathd: sdc: tur checker reports path is up Mar 18 13:23:59 localhost multipathd: 8:32: reinstated Mar 18 13:23:59 localhost multipathd: mpath0: remaining active paths: 2 Mar 18 13:23:59 localhost multipathd: dm-2: add map (uevent) Mar 18 13:23:59 localhost multipathd: dm-2: devmap already registered [root@localhost ~]# multipath -ll mpath0 (36001f93000a310000299000200000000) dm-2 XIOTECH,ISE1400 [size=1.1T][features=1 queue_if_no_path][hwhandler=0][rw] \_ round-robin 0 [prio=2][enabled] \_ 1:0:0:1 sdb 8:16 [active][ready] \_ 2:0:0:1 sdc 8:32 [active][ready] Great right? It says [rw] right there. Not so fast: [root@localhost ~]# touch /mnt/foo/blah touch: cannot touch `/mnt/foo/blah': Read-only file system OK, doesn't do it automatically, I'll just give it a little push: [root@localhost ~]# mount -o remount /mnt/foo mount: block device /dev/mapper/mpath0 is write-protected, mounting read-only The hell you are: [root@localhost ~]# mount -o remount,rw /mnt/foo mount: block device /dev/mapper/mpath0 is write-protected, mounting read-only Noooooooooo. I have tried all sorts of different mount/tune2fs/dmsetup commands and I cannot figure out how to get it to un-flag the block device as write-protected. Rebooting will fix it, but I'd much rather do it on-line. An hour of googling has gotten me nowhere either. Save me ServerFault.

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  • Scaling-out Your Services by Message Bus based WCF Transport Extension &ndash; Part 1 &ndash; Background

    - by Shaun
    Cloud computing gives us more flexibility on the computing resource, we can provision and deploy an application or service with multiple instances over multiple machines. With the increment of the service instances, how to balance the incoming message and workload would become a new challenge. Currently there are two approaches we can use to pass the incoming messages to the service instances, I would like call them dispatcher mode and pulling mode.   Dispatcher Mode The dispatcher mode introduces a role which takes the responsible to find the best service instance to process the request. The image below describes the sharp of this mode. There are four clients communicate with the service through the underlying transportation. For example, if we are using HTTP the clients might be connecting to the same service URL. On the server side there’s a dispatcher listening on this URL and try to retrieve all messages. When a message came in, the dispatcher will find a proper service instance to process it. There are three mechanism to find the instance: Round-robin: Dispatcher will always send the message to the next instance. For example, if the dispatcher sent the message to instance 2, then the next message will be sent to instance 3, regardless if instance 3 is busy or not at that moment. Random: Dispatcher will find a service instance randomly, and same as the round-robin mode it regardless if the instance is busy or not. Sticky: Dispatcher will send all related messages to the same service instance. This approach always being used if the service methods are state-ful or session-ful. But as you can see, all of these approaches are not really load balanced. The clients will send messages at any time, and each message might take different process duration on the server side. This means in some cases, some of the service instances are very busy while others are almost idle. For example, if we were using round-robin mode, it could be happened that most of the simple task messages were passed to instance 1 while the complex ones were sent to instance 3, even though instance 1 should be idle. This brings some problem in our architecture. The first one is that, the response to the clients might be longer than it should be. As it’s shown in the figure above, message 6 and 9 can be processed by instance 1 or instance 2, but in reality they were dispatched to the busy instance 3 since the dispatcher and round-robin mode. Secondly, if there are many requests came from the clients in a very short period, service instances might be filled by tons of pending tasks and some instances might be crashed. Third, if we are using some cloud platform to host our service instances, for example the Windows Azure, the computing resource is billed by service deployment period instead of the actual CPU usage. This means if any service instance is idle it is wasting our money! Last one, the dispatcher would be the bottleneck of our system since all incoming messages must be routed by the dispatcher. If we are using HTTP or TCP as the transport, the dispatcher would be a network load balance. If we wants more capacity, we have to scale-up, or buy a hardware load balance which is very expensive, as well as scaling-out the service instances. Pulling Mode Pulling mode doesn’t need a dispatcher to route the messages. All service instances are listening to the same transport and try to retrieve the next proper message to process if they are idle. Since there is no dispatcher in pulling mode, it requires some features on the transportation. The transportation must support multiple client connection and server listening. HTTP and TCP doesn’t allow multiple clients are listening on the same address and port, so it cannot be used in pulling mode directly. All messages in the transportation must be FIFO, which means the old message must be received before the new one. Message selection would be a plus on the transportation. This means both service and client can specify some selection criteria and just receive some specified kinds of messages. This feature is not mandatory but would be very useful when implementing the request reply and duplex WCF channel modes. Otherwise we must have a memory dictionary to store the reply messages. I will explain more about this in the following articles. Message bus, or the message queue would be best candidate as the transportation when using the pulling mode. First, it allows multiple application to listen on the same queue, and it’s FIFO. Some of the message bus also support the message selection, such as TIBCO EMS, RabbitMQ. Some others provide in memory dictionary which can store the reply messages, for example the Redis. The principle of pulling mode is to let the service instances self-managed. This means each instance will try to retrieve the next pending incoming message if they finished the current task. This gives us more benefit and can solve the problems we met with in the dispatcher mode. The incoming message will be received to the best instance to process, which means this will be very balanced. And it will not happen that some instances are busy while other are idle, since the idle one will retrieve more tasks to make them busy. Since all instances are try their best to be busy we can use less instances than dispatcher mode, which more cost effective. Since there’s no dispatcher in the system, there is no bottleneck. When we introduced more service instances, in dispatcher mode we have to change something to let the dispatcher know the new instances. But in pulling mode since all service instance are self-managed, there no extra change at all. If there are many incoming messages, since the message bus can queue them in the transportation, service instances would not be crashed. All above are the benefits using the pulling mode, but it will introduce some problem as well. The process tracking and debugging become more difficult. Since the service instances are self-managed, we cannot know which instance will process the message. So we need more information to support debug and track. Real-time response may not be supported. All service instances will process the next message after the current one has done, if we have some real-time request this may not be a good solution. Compare with the Pros and Cons above, the pulling mode would a better solution for the distributed system architecture. Because what we need more is the scalability, cost-effect and the self-management.   WCF and WCF Transport Extensibility Windows Communication Foundation (WCF) is a framework for building service-oriented applications. In the .NET world WCF is the best way to implement the service. In this series I’m going to demonstrate how to implement the pulling mode on top of a message bus by extending the WCF. I don’t want to deep into every related field in WCF but will highlight its transport extensibility. When we implemented an RPC foundation there are many aspects we need to deal with, for example the message encoding, encryption, authentication and message sending and receiving. In WCF, each aspect is represented by a channel. A message will be passed through all necessary channels and finally send to the underlying transportation. And on the other side the message will be received from the transport and though the same channels until the business logic. This mode is called “Channel Stack” in WCF, and the last channel in the channel stack must always be a transport channel, which takes the responsible for sending and receiving the messages. As we are going to implement the WCF over message bus and implement the pulling mode scaling-out solution, we need to create our own transport channel so that the client and service can exchange messages over our bus. Before we deep into the transport channel, let’s have a look on the message exchange patterns that WCF defines. Message exchange pattern (MEP) defines how client and service exchange the messages over the transportation. WCF defines 3 basic MEPs which are datagram, Request-Reply and Duplex. Datagram: Also known as one-way, or fire-forgot mode. The message sent from the client to the service, and no need any reply from the service. The client doesn’t care about the message result at all. Request-Reply: Very common used pattern. The client send the request message to the service and wait until the reply message comes from the service. Duplex: The client sent message to the service, when the service processing the message it can callback to the client. When callback the service would be like a client while the client would be like a service. In WCF, each MEP represent some channels associated. MEP Channels Datagram IInputChannel, IOutputChannel Request-Reply IRequestChannel, IReplyChannel Duplex IDuplexChannel And the channels are created by ChannelListener on the server side, and ChannelFactory on the client side. The ChannelListener and ChannelFactory are created by the TransportBindingElement. The TransportBindingElement is created by the Binding, which can be defined as a new binding or from a custom binding. For more information about the transport channel mode, please refer to the MSDN document. The figure below shows the transport channel objects when using the request-reply MEP. And this is the datagram MEP. And this is the duplex MEP. After investigated the WCF transport architecture, channel mode and MEP, we finally identified what we should do to extend our message bus based transport layer. They are: Binding: (Optional) Defines the channel elements in the channel stack and added our transport binding element at the bottom of the stack. But we can use the build-in CustomBinding as well. TransportBindingElement: Defines which MEP is supported in our transport and create the related ChannelListener and ChannelFactory. This also defines the scheme of the endpoint if using this transport. ChannelListener: Create the server side channel based on the MEP it’s. We can have one ChannelListener to create channels for all supported MEPs, or we can have ChannelListener for each MEP. In this series I will use the second approach. ChannelFactory: Create the client side channel based on the MEP it’s. We can have one ChannelFactory to create channels for all supported MEPs, or we can have ChannelFactory for each MEP. In this series I will use the second approach. Channels: Based on the MEPs we want to support, we need to implement the channels accordingly. For example, if we want our transport support Request-Reply mode we should implement IRequestChannel and IReplyChannel. In this series I will implement all 3 MEPs listed above one by one. Scaffold: In order to make our transport extension works we also need to implement some scaffold stuff. For example we need some classes to send and receive message though out message bus. We also need some codes to read and write the WCF message, etc.. These are not necessary but would be very useful in our example.   Message Bus There is only one thing remained before we can begin to implement our scaling-out support WCF transport, which is the message bus. As I mentioned above, the message bus must have some features to fulfill all the WCF MEPs. In my company we will be using TIBCO EMS, which is an enterprise message bus product. And I have said before we can use any message bus production if it’s satisfied with our requests. Here I would like to introduce an interface to separate the message bus from the WCF. This allows us to implement the bus operations by any kinds bus we are going to use. The interface would be like this. 1: public interface IBus : IDisposable 2: { 3: string SendRequest(string message, bool fromClient, string from, string to = null); 4:  5: void SendReply(string message, bool fromClient, string replyTo); 6:  7: BusMessage Receive(bool fromClient, string replyTo); 8: } There are only three methods for the bus interface. Let me explain one by one. The SendRequest method takes the responsible for sending the request message into the bus. The parameters description are: message: The WCF message content. fromClient: Indicates if this message was came from the client. from: The channel ID that this message was sent from. The channel ID will be generated when any kinds of channel was created, which will be explained in the following articles. to: The channel ID that this message should be received. In Request-Reply and Duplex MEP this is necessary since the reply message must be received by the channel which sent the related request message. The SendReply method takes the responsible for sending the reply message. It’s very similar as the previous one but no “from” parameter. This is because it’s no need to reply a reply message again in any MEPs. The Receive method takes the responsible for waiting for a incoming message, includes the request message and specified reply message. It returned a BusMessage object, which contains some information about the channel information. The code of the BusMessage class is 1: public class BusMessage 2: { 3: public string MessageID { get; private set; } 4: public string From { get; private set; } 5: public string ReplyTo { get; private set; } 6: public string Content { get; private set; } 7:  8: public BusMessage(string messageId, string fromChannelId, string replyToChannelId, string content) 9: { 10: MessageID = messageId; 11: From = fromChannelId; 12: ReplyTo = replyToChannelId; 13: Content = content; 14: } 15: } Now let’s implement a message bus based on the IBus interface. Since I don’t want you to buy and install the TIBCO EMS or any other message bus products, I will implement an in process memory bus. This bus is only for test and sample purpose. It can only be used if the service and client are in the same process. Very straightforward. 1: public class InProcMessageBus : IBus 2: { 3: private readonly ConcurrentDictionary<Guid, InProcMessageEntity> _queue; 4: private readonly object _lock; 5:  6: public InProcMessageBus() 7: { 8: _queue = new ConcurrentDictionary<Guid, InProcMessageEntity>(); 9: _lock = new object(); 10: } 11:  12: public string SendRequest(string message, bool fromClient, string from, string to = null) 13: { 14: var entity = new InProcMessageEntity(message, fromClient, from, to); 15: _queue.TryAdd(entity.ID, entity); 16: return entity.ID.ToString(); 17: } 18:  19: public void SendReply(string message, bool fromClient, string replyTo) 20: { 21: var entity = new InProcMessageEntity(message, fromClient, null, replyTo); 22: _queue.TryAdd(entity.ID, entity); 23: } 24:  25: public BusMessage Receive(bool fromClient, string replyTo) 26: { 27: InProcMessageEntity e = null; 28: while (true) 29: { 30: lock (_lock) 31: { 32: var entity = _queue 33: .Where(kvp => kvp.Value.FromClient == fromClient && (kvp.Value.To == replyTo || string.IsNullOrWhiteSpace(kvp.Value.To))) 34: .FirstOrDefault(); 35: if (entity.Key != Guid.Empty && entity.Value != null) 36: { 37: _queue.TryRemove(entity.Key, out e); 38: } 39: } 40: if (e == null) 41: { 42: Thread.Sleep(100); 43: } 44: else 45: { 46: return new BusMessage(e.ID.ToString(), e.From, e.To, e.Content); 47: } 48: } 49: } 50:  51: public void Dispose() 52: { 53: } 54: } The InProcMessageBus stores the messages in the objects of InProcMessageEntity, which can take some extra information beside the WCF message itself. 1: public class InProcMessageEntity 2: { 3: public Guid ID { get; set; } 4: public string Content { get; set; } 5: public bool FromClient { get; set; } 6: public string From { get; set; } 7: public string To { get; set; } 8:  9: public InProcMessageEntity() 10: : this(string.Empty, false, string.Empty, string.Empty) 11: { 12: } 13:  14: public InProcMessageEntity(string content, bool fromClient, string from, string to) 15: { 16: ID = Guid.NewGuid(); 17: Content = content; 18: FromClient = fromClient; 19: From = from; 20: To = to; 21: } 22: }   Summary OK, now I have all necessary stuff ready. The next step would be implementing our WCF message bus transport extension. In this post I described two scaling-out approaches on the service side especially if we are using the cloud platform: dispatcher mode and pulling mode. And I compared the Pros and Cons of them. Then I introduced the WCF channel stack, channel mode and the transport extension part, and identified what we should do to create our own WCF transport extension, to let our WCF services using pulling mode based on a message bus. And finally I provided some classes that need to be used in the future posts that working against an in process memory message bus, for the demonstration purpose only. In the next post I will begin to implement the transport extension step by step.   Hope this helps, Shaun All documents and related graphics, codes are provided "AS IS" without warranty of any kind. Copyright © Shaun Ziyan Xu. This work is licensed under the Creative Commons License.

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  • Update: Super Hero

    While I was looking for a completely different article back in 2007, I came across my Super Hero & Super Villain rating... Well, it was time for an update: Your Super Hero results: You are Spider-Man Spider-Man 75% Supergirl 70% Green Lantern 70% Robin 57% The Flash 55% Hulk 50% Catwoman 50% Superman 45% Batman 40% Wonder Woman 40% Iron Man 40% You are intelligent, witty, a bit geeky and have great power and responsibility. Click here to take the Superhero Personality Test

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  • Tuxedo Load Balancing

    - by Todd Little
    A question I often receive is how does Tuxedo perform load balancing.  This is often asked by customers that see an imbalance in the number of requests handled by servers offering a specific service. First of all let me say that Tuxedo really does load or request optimization instead of load balancing.  What I mean by that is that Tuxedo doesn't attempt to ensure that all servers offering a specific service get the same number of requests, but instead attempts to ensure that requests are processed in the least amount of time.   Simple round robin "load balancing" can be employed to ensure that all servers for a particular service are given the same number of requests.  But the question I ask is, "to what benefit"?  Instead Tuxedo scans the queues (which may or may not correspond to servers based upon SSSQ - Single Server Single Queue or MSSQ - Multiple Server Single Queue) to determine on which queue a request should be placed.  The scan is always performed in the same order and during the scan if a queue is empty the request is immediately placed on that queue and request routing is done.  However, should all the queues be busy, meaning that requests are currently being processed, Tuxedo chooses the queue with the least amount of "work" queued to it where work is the sum of all the requests queued weighted by their "load" value as defined in the UBBCONFIG file.  What this means is that under light loads, only the first few queues (servers) process all the requests as an empty queue is often found before reaching the end of the scan.  Thus the first few servers in the queue handle most of the requests.  While this sounds non-optimal, in fact it capitalizes on the underlying operating systems and hardware behavior to produce the best possible performance.  Round Robin scheduling would spread the requests across all the available servers and thus require all of them to be in memory, and likely not share much in the way of hardware or memory caches.  Tuxedo's system maximizes the various caches and thus optimizes overall performance.  Hopefully this makes sense and now explains why you may see a few servers handling most of the requests.  Under heavy load, meaning enough load to keep all servers that can handle a request busy, you should see a relatively equal number of requests processed.  Next post I'll try and cover how this applies to servers in a clustered (MP) environment because the load balancing there is a little more complicated. Regards,Todd LittleOracle Tuxedo Chief Architect

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  • Advanced System Monitor/Task Manager?

    - by instanceofTom
    When using kubuntu I noticed that the standard task manager/system monitor was a bit more capable than gnome-system-monitor, is there a more advanced system/task monitor for ubuntu that is based on gnome opposed to KDE? Specifically the features from the Kubuntu task manager that I am looking for are the ability to control the I/O priority of individual processes (not just their nice), and the ability to control the I/O scheduling algorithm ( round-robin, FIFO, etc). What are my options?

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  • Friday Fun: Archers Oath

    - by Asian Angel
    This week’s game puts your archery skills to the test as you race against time to save innocent captives from the hangman’s noose. Are you good enough to show Robin Hood a thing or two about using a bow or will you be shot down in shame? How to Stress Test the Hard Drives in Your PC or Server How To Customize Your Android Lock Screen with WidgetLocker The Best Free Portable Apps for Your Flash Drive Toolkit

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  • Customers Go On Record About Oracle ERP and HCM Cloud Services

    - by Kathryn Perry
    Listen to these Oracle customers from Red Robin, Herbalife, LendingClub, and Cricket.talk about how they're using Oracle ERP and HCM Cloud Services. Collectively they're driving cost savings, managing global, fast paced growth, automating processes, implementing quickly in the cloud, and much more. Here's the video link: http://www.youtube.com/user/FusionAppsAtOracle

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  • Sticky connection and HTTPS support for HAProxy

    - by Saif
    Hi Mates, We have 2 HTTP Load balancer with HAproxy and heartbeat. There are 4 apache nodes in this cluster. It's doing round robin load balancing. The HTTP cluster working fine. We are having problem with our portal because it uses SSO. We need sticky connection support in our HAproxy. Also we need load balancing for HTTPS traffic. Here's our HAproxy conf file. global # to have these messages end up in /var/log/haproxy.log you will # need to: # # 1) configure syslog to accept network log events. This is done # by adding the '-r' option to the SYSLOGD_OPTIONS in # /etc/sysconfig/syslog # # 2) configure local2 events to go to the /var/log/haproxy.log # file. A line like the following can be added to # /etc/sysconfig/syslog # # local2.* /var/log/haproxy.log # log 127.0.0.1 local0 log 127.0.0.1 local1 notice chroot /var/lib/haproxy pidfile /var/run/haproxy.pid maxconn 4000 user haproxy group haproxy daemon # turn on stats unix socket stats socket /var/lib/haproxy/stats #--------------------------------------------------------------------- # common defaults that all the 'listen' and 'backend' sections will # use if not designated in their block #--------------------------------------------------------------------- defaults mode http log global option httplog option dontlognull option http-server-close option forwardfor except 127.0.0.0/8 option redispatch retries 3 timeout http-request 10s timeout queue 1m timeout connect 10s timeout client 1m timeout server 1m timeout http-keep-alive 10s timeout check 10s maxconn 3000 #--------------------------------------------------------------------- # main frontend which proxys to the backends #--------------------------------------------------------------------- frontend main *:5000 acl url_static path_beg -i /static /images /javascript /stylesheets acl url_static path_end -i .jpg .gif .png .css .js use_backend static if url_static default_backend app #--------------------------------------------------------------------- # static backend for serving up images, stylesheets and such #--------------------------------------------------------------------- backend static balance roundrobin server static 127.0.0.1:4331 check #--------------------------------------------------------------------- # round robin balancing between the various backends #--------------------------------------------------------------------- backend app listen ha-http 10.190.1.28:80 mode http stats enable stats auth admin:xxxxxx balance roundrobin cookie JSESSIONID prefix option httpclose option forwardfor option httpchk HEAD /haproxy.txt HTTP/1.0 server apache1 portal-04:80 cookie A check server apache2 im-01:80 cookie B check server apache3 im-02:80 cookie B check server apache4 im-03:80 cookie B check Please advice. Thanks for your help in advance.

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  • Howo to get Multipath IO with Dell MD3600i into active/active setup?

    - by Disco
    I'm desperately trying to improve performance of my SAN connection. Here's what i have: [root@xnode1 dell]# multipath -ll mpath1 (36d4ae520009bd7cc0000030e4fe8230b) dm-2 DELL,MD36xxi [size=5.5T][features=3 queue_if_no_path pg_init_retries 50][hwhandler=1 rdac][rw] \_ round-robin 0 [prio=200][active] \_ 18:0:0:0 sdb 8:16 [active][ready] \_ 19:0:0:0 sdd 8:48 [active][ghost] \_ 20:0:0:0 sdf 8:80 [active][ghost] \_ 21:0:0:0 sdh 8:112 [active][ready] And multipath.conf : defaults { udev_dir /dev polling_interval 5 prio_callout none rr_min_io 100 max_fds 8192 user_friendly_names yes path_grouping_policy multibus default_features "1 fail_if_no_path" } blacklist { device { vendor "*" product "Universal Xport" } } devices { device { vendor "DELL" product "MD36xxi" path_checker rdac path_selector "round-robin 0" hardware_handler "1 rdac" failback immediate features "2 pg_init_retries 50" no_path_retry 30 rr_min_io 100 prio_callout "/sbin/mpath_prio_rdac /dev/%n" } } And sessions. [root@xnode1 dell]# iscsiadm -m session tcp: [13] 10.0.51.220:3260,1 iqn.1984-05.com.dell:powervault.md3600i.6d4ae520009bd7cc000000004fd7507c tcp: [14] 10.0.50.221:3260,2 iqn.1984-05.com.dell:powervault.md3600i.6d4ae520009bd7cc000000004fd7507c tcp: [15] 10.0.51.221:3260,2 iqn.1984-05.com.dell:powervault.md3600i.6d4ae520009bd7cc000000004fd7507c tcp: [16] 10.0.50.220:3260,1 iqn.1984-05.com.dell:powervault.md3600i.6d4ae520009bd7cc000000004fd7507c I'm getting very poor read performance : dd if=/dev/mapper/mpath1 of=/dev/null bs=1M count=1000 The SAN is configured as follows: CTRL0,PORT0 : 10.0.50.220 CTRL0,PORT1 : 10.0.50.221 CTRL1,PORT0 : 10.0.51.220 CTRL1,PORT1 : 10.0.51.221 And on the host : IF0 : 10.0.50.1 IF1 : 10.0.51.1 (Dual 10GbE Ethernet Card Intel DA2) It's connected to a 10gbE switch dedicated for SAN traffic. My questions being; why the connection is set up as 'ghost' and not 'ready' like an active/active configuration ?

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  • Sticky connection and HTTPS support for HAProxy

    - by Saif
    We have 2 HTTP Load balancer with HAproxy and heartbeat. There are 4 apache nodes in this cluster. It's doing round robin load balancing. The HTTP cluster working fine. We are having problem with our portal because it uses SSO. We need sticky connection support in our HAproxy. Also we need load balancing for HTTPS traffic. Here's our HAproxy conf file. global # to have these messages end up in /var/log/haproxy.log you will # need to: # # 1) configure syslog to accept network log events. This is done # by adding the '-r' option to the SYSLOGD_OPTIONS in # /etc/sysconfig/syslog # # 2) configure local2 events to go to the /var/log/haproxy.log # file. A line like the following can be added to # /etc/sysconfig/syslog # # local2.* /var/log/haproxy.log # log 127.0.0.1 local0 log 127.0.0.1 local1 notice chroot /var/lib/haproxy pidfile /var/run/haproxy.pid maxconn 4000 user haproxy group haproxy daemon # turn on stats unix socket stats socket /var/lib/haproxy/stats #--------------------------------------------------------------------- # common defaults that all the 'listen' and 'backend' sections will # use if not designated in their block #--------------------------------------------------------------------- defaults mode http log global option httplog option dontlognull option http-server-close option forwardfor except 127.0.0.0/8 option redispatch retries 3 timeout http-request 10s timeout queue 1m timeout connect 10s timeout client 1m timeout server 1m timeout http-keep-alive 10s timeout check 10s maxconn 3000 #--------------------------------------------------------------------- # main frontend which proxys to the backends #--------------------------------------------------------------------- frontend main *:5000 acl url_static path_beg -i /static /images /javascript /stylesheets acl url_static path_end -i .jpg .gif .png .css .js use_backend static if url_static default_backend app #--------------------------------------------------------------------- # static backend for serving up images, stylesheets and such #--------------------------------------------------------------------- backend static balance roundrobin server static 127.0.0.1:4331 check #--------------------------------------------------------------------- # round robin balancing between the various backends #--------------------------------------------------------------------- backend app listen ha-http 10.190.1.28:80 mode http stats enable stats auth admin:xxxxxx balance roundrobin cookie JSESSIONID prefix option httpclose option forwardfor option httpchk HEAD /haproxy.txt HTTP/1.0 server apache1 portal-04:80 cookie A check server apache2 im-01:80 cookie B check server apache3 im-02:80 cookie B check server apache4 im-03:80 cookie B check Please advice. Thanks for your help in advance.

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  • Linux NIC Bonding Issue (CentOS 4 / RHEL 3)

    - by jinanwow
    I am having an issue with bonding NICs on CentOS 4. It appears the bonding driver does work, but it is stuck in round-robin mode and I am trying to get to active-backup. The current config is: ifcfg-bond0 DEVICE=bond0 IPADDR=192.168.204.18 NETMASK=255.255.255.0 ONBOOT=yes BOOTPROTO=none USERCTL=no TYPE=Bonding BONDING_OPTS="mode=1 miimon=100" ifcfg-eth1 DEVICE=eth1 BOOTPROTO=none ONBOOT=yes TYPE=Ethernet MASTER=bond0 SLAVE=yes ifcfg-eth3 DEVICE=eth3 ONBOOT=yes BOOTPROTO=none TYPE=Ethernet MASTER=bond0 SLAVE=yes cat /proc/net/bonding/bond0 Ethernet Channel Bonding Driver: v2.6.3-rh (June 8, 2005) Bonding Mode: load balancing (round-robin) MII Status: up MII Polling Interval (ms): 0 Up Delay (ms): 0 Down Delay (ms): 0 Slave Interface: eth1 MII Status: up Link Failure Count: 0 Permanent HW addr: 00:17:a4:8f:94:b1 Slave Interface: eth3 MII Status: up Link Failure Count: 0 Permanent HW addr: 00:1b:21:56:b8:69 cat /etc/modprobe.conf alias eth0 tg3 alias eth1 tg3 alias eth3 e1000 alias eth2 e1000 alias bond0 bonding options bond0 mode=1 miimon=100 I have tried moving the bonding information out of the ifcfg-bond0 into the modprobe configuration file. It seems that it is stuck in RR and I am trying to get it into the Active-backup (mode 1) state. Any ideas what would be causing this issue?

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  • Backbone.Marionette - Collection within CompositeView, which itself is nested in a CollectionView

    - by nicefinly
    *UPDATE: The problem probably involves the tour-template as I've discovered that it thinks the 'name' attribute is undefined. This leads me to think that it's not an array being passed on to the ToursView, but for some reason a string. * After studying similar questions on StackOverflow: How to handle nested CompositeView using Backbone.Marionette? How do you properly display a Backbone marionette collection view based on a model javascript array property? Nested collections with Backbone.Marionette ... and Derick Bailey's excellent blog's on this subject: http://lostechies.com/derickbailey/2012/04/05/composite-views-tree-structures-tables-and-more/ ... including the JSFiddle's: http://jsfiddle.net/derickbailey/AdWjU/ I'm still having trouble with a displaying the last node of a nested CollectionView of CompositeViews. It is the final CollectionView within each CompositeView that is causing the problem. CollectionView { CompositeView{ CollectionView {} //**<-- This is the troublemaker!** } } NOTE: I have already made a point of creating a valid Backbone.Collection given that the collection passed on to the final, child CollectionView is just a simple array. Data returned from the api to ToursList: [ { "id": "1", "name": "Venice", "theTours": "[ {'name': u'test venice'}, {'name': u'test venice 2'} ]" }, { "id": "2", "name": "Rome", "theTours": "[ {'name': u'Test rome'} ]" }, { "id": "3", "name": "Dublin", "theTours": "[ {'name': u'test dublin'}, {'name': u'test dublin 2'} ]" } ] I'm trying to nest these in a dropdown where the nav header is the 'name' (i.e. Dublin), and the subsequent li 's are the individual tour names (i.e. 'test dublin', 'test dublin2', etc.) Tour Models and Collections ToursByLoc = TastypieModel.extend({}); ToursList = TastypieCollection.extend({ model: ToursByLoc, url:'/api/v1/location/', }); Tour Views ToursView = Backbone.Marionette.ItemView.extend({ template: '#tour-template', tagName: 'li', }); ToursByLocView = Backbone.Marionette.CompositeView.extend({ template: '#toursByLoc-template', itemView: ToursView, initialize: function(){ //As per Derick Bailey's comments regarding the need to pass on a //valid Backbone.Collection to the child CollectionView //REFERENCE: http://stackoverflow.com/questions/12163118/nested-collections-with-backbone-marionette var theTours = this.model.get('theTours'); this.collection = new Backbone.Collection(theTours); }, appendHtml: function(collectionView, itemView){ collectionView.$('div').append(itemView.el); } }); ToursListView = Backbone.Marionette.CollectionView.extend({ itemView: ToursByLocView, }); Templates <script id="tour-template" type="text/template"> <%= name %> </script> <script id="toursByLoc-template" type="text/template"> <li class="nav-header"><%= name %></li> <div class="indTours"></div> <li class="divider"></li> </script>

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  • How to best tune my SAN/Initiators for best performance?

    - by Disco
    Recent owner of a Dell PowerVault MD3600i i'm experiencing some weird results. I have a dedicated 24x 10GbE Switch (PowerConnect 8024), setup to jumbo frames 9K. The MD3600 has 2 RAID controllers, each has 2x 10GbE ethernet nics. There's nothing else on the switch; one VLAN for SAN traffic. Here's my multipath.conf defaults { udev_dir /dev polling_interval 5 selector "round-robin 0" path_grouping_policy multibus getuid_callout "/sbin/scsi_id -g -u -s /block/%n" prio_callout none path_checker readsector0 rr_min_io 100 max_fds 8192 rr_weight priorities failback immediate no_path_retry fail user_friendly_names yes # prio rdac } blacklist { device { vendor "*" product "Universal Xport" } # devnode "^sd[a-z]" } devices { device { vendor "DELL" product "MD36xxi" path_grouping_policy group_by_prio prio rdac # polling_interval 5 path_checker rdac path_selector "round-robin 0" hardware_handler "1 rdac" failback immediate features "2 pg_init_retries 50" no_path_retry 30 rr_min_io 100 prio_callout "/sbin/mpath_prio_rdac /dev/%n" } } And iscsid.conf : node.startup = automatic node.session.timeo.replacement_timeout = 15 node.conn[0].timeo.login_timeout = 15 node.conn[0].timeo.logout_timeout = 15 node.conn[0].timeo.noop_out_interval = 5 node.conn[0].timeo.noop_out_timeout = 10 node.session.iscsi.InitialR2T = No node.session.iscsi.ImmediateData = Yes node.session.iscsi.FirstBurstLength = 262144 node.session.iscsi.MaxBurstLength = 16776192 node.conn[0].iscsi.MaxRecvDataSegmentLength = 262144 After my tests; i can barely come to 200 Mb/s read/write. Should I expect more than that ? Providing it has dual 10 GbE my thoughts where to come around the 400 Mb/s. Any ideas ? Guidelines ? Troubleshooting tips ?

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  • Apache httpd workers retry

    - by David Newcomb
    I have an Apache httpd web server running mod_proxy and mod_proxy_balancer. The whole of /somedir is sent to 2 worker machines which service the requests using the round robin scheduler. Each worker machine is running IIS but I don't think that is important. I can demonstrate the load balancer working by repeatedly requesting a single page which contains the IP address of the machine and can see that it switches from one to the other in a predictable round robin fashion. If I switch off one of the IIS servers and start requesting the same page then each page only contains the IP address of the machine that is up. However, if I start IIS and don't run my IIS application then /somedir returns 500 (as it should). I've added 500 to the failonstatus (Apache 2.4) so when it hits the error Apache places the worker machine into error state. Apache still returns the proxy error to the client though. How can I make Apache catch the proxy failure and retry using a different worker in the same way that a connection failure does. Update There is almost the same question asked in StackOverflow so joining them together. http://stackoverflow.com/questions/11083707/httpd-mod-proxy-balancer-failover-failonstatus-transperant-switching

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  • CodePlex Daily Summary for Wednesday, October 10, 2012

    CodePlex Daily Summary for Wednesday, October 10, 2012Popular ReleasesA C# 4.0 Push Notification Helper Library for WP7.0 & WP7.1: Easy Notification 1.0.0: New Feature - Send Tile, Toast & Raw Notifications to Windows Phone Devices. New Feature - Supports Windows Phone 7.0 & Windows Phone 7.1. New Feature - Validation rules are in-built for Push Notification Messages. New Feature - Strongly typed interfaces. New Feature - Supports synchronous & asynchronous methods to send notifications. New Feature - Supports authenticated notifications using X509 Certificates. New Feature - Supports Callback Registration Requests. New Feature - S...D3 Loot Tracker: 1.5.4: Fixed a bug where the server ip was not logged properly in the stats file.Captcha MVC: Captcha Mvc 2.1.2: v 2.1.2: Fixed problem with serialization. Made all classes from a namespace Jetbrains.Annotaions as the internal. Added autocomplete attribute and autocorrect attribute for captcha input element. Minor changes. v 2.1.1: Fixed problem with serialization. Minor changes. v 2.1: Added support for storing captcha in the session or cookie. See the updated example. Updated example. Minor changes. v 2.0.1: Added support for a partial captcha. Now you can easily customize the layout, s...DotNetNuke® Community Edition CMS: 06.02.04: Major Highlights Fixed issue where the module printing function was only visible to administrators Fixed issue where pane level skinning was being assigned to a default container for any content pane Fixed issue when using password aging and FB / Google authentication Fixed issue that was causing the DateEditControl to not load the assigned value Fixed issue that stopped additional profile properties to be displayed in the member directory after modifying the template Fixed er...Online Image Editor: Online Image Editor v1.1: If you have problems with this tool, please email me at amisouvikdas@gmail.com or You can also participate this project to improve this.Advanced DataGridView with Excel-like auto filter: 1.0.0.0: ?????? ??????Microsoft Ajax Minifier: Microsoft Ajax Minifier 4.69: Fix for issue #18766: build task should not build the output if it's newer than all the input files. Fix for Issue #18764: build taks -res switch not working. update build task to concatenate input source and then minify, rather than minify and then concatenate. include resource string-replacement root name in the assumed globals list. Stop replacing new Date().getTime() with +new Date -- the latter is smaller, but turns out it executes up to 45% slower. add CSS support for single-...WinRT XAML Toolkit: WinRT XAML Toolkit - 1.3.3: WinRT XAML Toolkit based on the Windows 8 RTM SDK. Download the latest source from the SOURCE CODE page. For compiled version use NuGet. You can add it to your project in Visual Studio by going to View/Other Windows/Package Manager Console and entering: PM> Install-Package winrtxamltoolkit Features Attachable Behaviors AwaitableUI extensions Controls Converters Debugging helpers Extension methods Imaging helpers IO helpers VisualTree helpers Samples Recent changes NOTE:...DevLib: 69721 binary dll: 69721 binary dllVidCoder: 1.4.4 Beta: Fixed inability to create new presets with "Save As".MCEBuddy 2.x: MCEBuddy 2.3.2: Changelog for 2.3.2 (32bit and 64bit) 1. Added support for generating XBMC XML NFO files for files in the conversion queue (store it along with the source video with source video name.nfo). Right click on the file in queue and select generate XML 2. UI bugifx, start and end trim box locations interchanged 3. Added support for removing commercials from non DVRMS/WTV files (MP4, AVI etc) 4. Now checking for Firewall port status before enabling (might help with some firewall problems) 5. User In...DotNetNuke Boards: 01.00.00: This beta release represents the end of training session 1, based on jQuery and Knockout integration in DotNetNuke 6.2.3. It is designed to allow a single user or multiple users to add/edit/delete cards but no cards can be assigned to anyone at this point. This release is not intended for production use!Sandcastle Help File Builder: SHFB v1.9.5.0 with Visual Studio Package: General InformationIMPORTANT: On some systems, the content of the ZIP file is blocked and the installer may fail to run. Before extracting it, right click on the ZIP file, select Properties, and click on the Unblock button if it is present in the lower right corner of the General tab in the properties dialog. This release supports the Sandcastle October 2012 Release (v2.7.1.0). It includes full support for generating, installing, and removing MS Help Viewer files. This new release suppor...ClosedXML - The easy way to OpenXML: ClosedXML 0.68.0: ClosedXML now resolves formulas! Yes it finally happened. If you call cell.Value and it has a formula the library will try to evaluate the formula and give you the result. For example: var wb = new XLWorkbook(); var ws = wb.AddWorksheet("Sheet1"); ws.Cell("A1").SetValue(1).CellBelow().SetValue(1); ws.Cell("B1").SetValue(1).CellBelow().SetValue(1); ws.Cell("C1").FormulaA1 = "\"The total value is: \" & SUM(A1:B2)"; var...Json.NET: Json.NET 4.5 Release 10: New feature - Added Portable build to NuGet package New feature - Added GetValue and TryGetValue with StringComparison to JObject Change - Improved duplicate object reference id error message Fix - Fixed error when comparing empty JObjects Fix - Fixed SecAnnotate warnings Fix - Fixed error when comparing DateTime JValue with a DateTimeOffset JValue Fix - Fixed serializer sometimes not using DateParseHandling setting Fix - Fixed error in JsonWriter.WriteToken when writing a DateT...Readable Passphrase Generator: KeePass Plugin 0.7.2: Changes: Tested against KeePass 2.20.1 Tested under Ubuntu 12.10 (and KeePass 2.20) Added GenerateAsUtf8 method returning the encrypted passphrase as a UTF8 byte array.JSLint for Visual Studio 2010: 1.4.2: 1.4.2patterns & practices: Prism: Prism for .NET 4.5: This is a release does not include any functionality changes over Prism 4.1 Desktop. These assemblies target .NET 4.5. These assemblies also were compiled against updated dependencies: Unity 3.0 and Common Service Locator (Portable Class Library).Snoop, the WPF Spy Utility: Snoop 2.8.0: Snoop 2.8.0Announcing Snoop 2.8.0! It's been exactly six months since the last release, and this one has a bunch of goodies in it. In particular, there is now a PowerShell scripting tab, compliments of Bailey Ling. With this tab, the possibilities are limitless. It basically lets you automate/script the application that you are Snooping. Bailey has a couple blog posts (one and two) on his tab already, and I am sure more is to come. Please note that if you do not have PowerShell installed, y....NET Micro Framework: .NET MF 4.3 (Beta): This is the 4.3 Beta version of the .NET Micro Framework. Feature List for v4.3 Support for Visual Studio 2012 (including the Windows Desktop Express version) All v4.2 QFEs features and bug fixes (PWM enhancements, lwIP and network driver reliability improvements, Analog Output, WinUSB and latest GCC support) Improved diagnostic information for deployment Decreased boot time Bug fixes Work Item 1736 - Create link for MFDeploy under start menu Work Item 1504 - Customizing lwIP o...New Projectsadcc2: adccAP.Framework: This a asp.net mvc3 of test web site .EFCodeFirst: Projeto criado para experimentos e estudos com o Entity FrameworkEXPS-RAT: HelloFiskalizacija za developere: Projekt je namijenjen razvojnim inženjerima, programerima, developerima i svima ostalima koji se bave razvojem programskih rješenja za fiskalne blagajne.Galleriffic App for SharePoint 2013: Galleriffic App is an app part for SharePoint 2013 to display a picture gallery with cool JQuery animations and effects. Hack.net: Hack.net is a Roguelike clone similar to NetHack or Roguelike.Inno Setup For .NET Application: This is a simple inno setup for .net developerJava Special Functions Library: Java Special Functions Library implemented as a public class part of my larger mathematical package.LocalFileOpener: The LocalFileOpener plugin opens an intent to help you easily open local files on the device under installed applications.localizr - .NET Collaborative Translation & Localization: Localizr is a platform for collaborative localization and translation of .NET projects.Metro UI CSS: Metro UI CSS a set of styles to create a site with an interface similar to Windows 8 Metro UI. MoskieDotNet: A sandbox for me learn some new technologies.Mouse Automation: Allows a user to automate repetitive clicking within EverQuestMS SQL DB Schema Updater: Simple tool for updating MS SQL database schema based on "ideal" database model.n8design Tools: Tools any Source Code by Stefan Bauer.NasosCS: ???? ?? ??????Pokemonochan: ALright this is a Pokemon MMo bound to come out someday!PotatoSoft: ?????????????!Power Mirrors: Leverage the usefulness of SQL Server mirrors using PowerShell and SMO. Create mirrors from scratch, assign witnesses and test failovers, all from PowerShell! Project13251010: sdfdReal Time Data Bus: A collection of real time data bus implementations.Ricky Tailor's ASP.NET Web 2.0 Project: 7COM0203 Web Scripting And Content Creation Task 1. SampleTFS2: Sample Projectslotcarduino - An Arduino based slotcar timing project: Slotcar timing project based on Arduino Uno/Mega 2560. Standalone system with serial enabled graphic display.System.Data.Entity.Repository: Entity framework code first framework wrapper with support for generic repository pattern, N-Tier application and Transaction Management for rapid developmentTest Marron: This project is a test to explore codeplexTmib Video Downloader: A small youtube video downloader. Created in C#Web Scripting & Content Creation: Fhame Rashid MSc Software Engineering Module Log: Web-Scripting and Content Creationwebbase: webbaseWebScriptingandContentCreation: This project is for the MSc module Web Scripting and Content Creation.Zuordnung: Zuordnung

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