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• Technology mash: is this possible?

  - by Jon Story

  I'm in the process of setting up my own DNS+hosting on a couple of VPS and my home machines, mostly for academic/learning purposes, but also for convenient accessing of my files, hosting my personal websites, private git repositories etc. I've got a main web server with DNS, and a slave DNS server. I've also got a couple of machines at home doing file hosting, video streaming and all that fun stuff. I'm intending to use my VPS's to provide myself with a dynamic DNS system so that I can point mydomain.com at my DNS servers, with home.mydomain.com going into my home network via a raspberry pi. HOWEVER.... I've not got access to the network infrastructure at home (rented accommodation with managed internet), so I can't forward the ports on the router to my own machines. As such, I'm wondering if it's possible to route all the traffic via an SSH/HTTP tunnel through one of the VPS? My plan is to have the raspberry pi provide a VPN into my home network. The raspberry pi uses SSH to connect to the VPS, and the VPS forwards any traffic to home.mydomain.com via the tunnel to the raspberry pi. Is this even possible, and how do I go about it? I don't mind getting my hands dirty with coding and low level tools, I'm just not sure where to start or what the best way to go about it is.

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• Is there a better way to do bonded vlan tagged interfaces with XEN

  - by AJ01

  We have a number of XEN servers all running CentOS or RHEL. The VM's that they run are all required to be on their own VLAN for no other reason than the customer expects them to be. Long story short however, I can't change this right now. We are also required to have bonding enabled on the interfaces. So to accommodat this we enslave eth1 and eth2 to bond0. We then create a seperate interface called bond0.VLANID where VLANID corresponds to the correct vlan; eg ifcfg-bond0.204 DEVICE=bond0.204 BOOTPROTO=static ONBOOT=yes VLAN=yes BRIDGE=xenvlan204 Bridge to XEN As you will see, we eventually have to bridge this out to XEN, and we do this by adding another interface called xenvlan204 (in this instance) which contains; ifcfg-xenvlan204 DEVICE=xenvlan204 BOOTPROTO=none ONBOOT=yes TYPE=bridge XEN Vm Config Finally in our XEN config for each VM, we add vif = [ "bridge=xenvlan204" ] This then allows the vm host to access that particular vlan The Problem We've noticed a few problems with this setup. One being that we currently create the interfaces manually. Which means if we add more vlan enabled interfaces and bridges we usually have to restart xend which is something I'm not so hot about. Also lower level staff have their heads melted by the number of interfaces and the risk of a mistake occurring is high. Secondly, it can take sometime for a host to come up if it has a number of vlan taged interfaces. Thirdly, its just not scaling well on the management aspects The Question Is there a better more flexible way to do this (in particular with Xen that ships with centos 5.3, 5.4 and 5.5 as we have to support all three) that leverages either scripting or other solutions to allow an arbitrary amount of interfaces to be created when a vm is instanced. Your advise and expertise is more that welcomed.

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• How to point any *.mydomain variation to localhost (for development)?

  - by user41339

  Hi all. I am developing a site, which will make use of any given [variation of] subdomain name part (that is, the part prefixed before the host name and, optionally, the TLD part). I would imagine that in production, that would be an easy feat - make sure the DNS for second-level domain name part points to an IP, set up Apache2 virtual host to listen on that (or any) IP port 80, and just use PHP to make decisions based on the "Host" request header. However, currently the site is localhost, since I am developing it using my workstation, so first I patched the /etc/hosts to include: 127.0.0.1 mydomain I only used one name part (arguably a custom TLD) so as to not interfere with the Internet domain names. Then I set up a VirtualHost directive for Apache 2.2 like: <VirtualHost *:80> ServerName mydomain But now I can see that f.e. example.mydomain does not point to localhost, meaning the the /etc/hosts addition is not effective for "something.mydomain". It appears the rules are taken verbatim, and also I have checked that wildcards like *.mydomain are not allowed. Is there a solution for this?

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• What is the max supported number of SATA devices (using cable adapters) on a Dell SAS 6/iR adapter?

  - by Zac B

  I've got a Dell SAS 6/iR PCI-E adapter. I don't have a multiplier backplane. I'm planning on connecting SATA (non SAS) drives. If I buy cable adapters only (ones that split a SAS connector on the card to a certain number of SATA cables), how many drives can I connect to this card? The way I see it, there are two limitations: a limitation imposed by the theoretical max number of devices supported on the card (which I've dug through the specs to find, but haven't seen yet), and a limitation imposed by the number of SAS plugs on the card multiplied by the number of SATA cables that come out of the highest-multiplying splitter I can buy. The answer to my question would be the minimum of those two limitations. I've seen 4x SATA coming out of some splitters; are there any that have more? Alternatively, if this is an RTFM question, does anyone have a good link to a "this is how SAS works, this is how you figure out the max number of devices, and this is how the concepts of 'ports', 'lanes', 'endpoint devices', and 'connectors' all relate in SAS-land" document? I've looked around on the Dell docs, but haven't found anything that explains this to someone at my level of understanding of SAN/enterprise storage technologies. Cheers!

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• Broad Band LAN connection through existing 6 wire phone line ( no phone connected )

  - by Paul Taylor

  I have an (up to but never achieved ) 10 mb broadband signal coming into my house along the telephone line. The modem then connects the broadband signal via a LAN connection and Wi-Fi signal to my computers and iPad. My workshop desk is 54 yards (approx. 50m) downhill from the modem (part of a separate building) – too far to give a good direct signal. The inside corner of the workshop (by a window) receives a weak signal. I have a disconnected telephone cable consisting of 6 wires going from the house to the workshop. The telephone is no longer used in the workshop - we use our mobile number for business calls. A broad band signal using the cable would not have to share with a phone. What would be the most economic price/efficient way to get the broadband signal to the workshop? I am writing in hope that since the telephone didn't need the six wires, an Ethernet connection might be similar and not need all the eight wires for a LAN connection. In theory could use the telephone wire to pull an Ethernet cable trough the underground pipe but I doubt if the cable would survive the strain. The broad band connection in the workshop does not have to have network facility. My skill level is high enough to do house wiring, plumbing and gas fitting; so given any sound advice and a wiring diagram or instructions I can probably work out the rest myself.

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• Improving performance by using an additional static file server

  - by Max

  Hello there, I´m planning for a large website that includes many static assets (js, css, images and thumbnails) in the generated pages. That website will use TYPO3 as CMS (is is a customer requirement). I guess I could seriously improve performance / page load times by using a two server setup. One server where the main application (PHP) runs and another one where the static files sit being served by a trimmed down version of apache or something like lighthttpd. Including e. g. js or css files from the file server is of course no big deal. Just use an absolute url http://static.example.com/js/main.js and be done with it. But: that website will have pages with MANY thumbnails of e. g. product images on it. So I see two problems when the main application tries to create a thumbnail of some image: the original image like products/some.jpg is uploaded on the static file server and therefore not on the same server as the PHP application which tries to create the thumbnail. TYPO3 writes created thumbnails to a temp directory which is expected to be on the same server. Therefore, hundreds of thumbnails will be written and served from that temp directory which is on the same server as the main application - the static file server is in that case basically useless, all thumbnails will be requested from the server of the main application. So, my question is: how to overcome this shortcomings? Is it possible to "symlink" some directories to another server? So, for example, if PHP tries to open the original products image for thumbnail creation with imagecreate("products/some.jpg") the products folder actually "points" to the products folder on the static image server? I know something like this can be done with .htaccess but is it possible on file system level?

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• Ubuntu 10.10 forgets desktop theme.

  - by Marcelo Cantos

  I am running Ubuntu in VirtualBox (on a Windows 7 host). Several times now, the top-level menu bar, the task bar — and seemingly every system dialog — have forgotten the out-of-the-box "Ambiance" theme they conform to when I first installed the system. Window captions still preserve the theme, but pretty much nothing else does. I have searched high and low on Google for assistance with this problem. Everything I've found suggests either running some gconf reset or deleting .gconf* .gnome* and other similar directories. I have followed all this advice and nothing works. I still get a boring Windows-95-style gray 3D look and feel. On previous occasions, after much messing around I've given up and rebooted the VM instance, and been pleasantly suprised to see the original "Ambience" theme restored throughout the UI, but invariably it disappears again some time later, usually after a reboot, so I can never figure out what I did that broke it. Here's a sample from Ubuntu's site of what I want it to look like. And here's a screenshot of my system as it currently looks. Also note that my GNOME Terminals normally have a nice purple semi-translucent look, and as can be seen from the screenshot, they are now just a solid matt white. This last time (just this morning), trying numerous combinations all the usual tricks and rebooting several times hasn't fixed it, so here I am on SU wondering: How do I recover the out-of-the-box theme for my Gnome/Ubuntu desktop, noting that blowing away all config files — as suggested in many places online — fails to achieve this? EDIT: It might help to know that it seems to fail either after I resize the VM instance, forcing the Ubuntu desktop to resize itself, or after I play around with Compiz settings. I haven't been able to figure out which of these it is, and it could be neither. Given the amount of pain I have had to go through to get things back to normal (and given that I am at a loss as to how to do so), it has proven difficult to definitively isolate the cause.

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• Setup: Eclipse in Ubuntu with Apache2 and Subversion

  - by Ricalsin

  Trying to setup Eclispe. I am running ubuntu 10.10 (Maverick). Apache2.2.16 Subversion 1.6.12 The Eclipse help/about/installed software says: Eclipse Platform 3.5.2 Subclipse 1.0.0 Version Control with Subversion 1.1.1 The Subclips wiki I followed is here I have installed the libsvn-java app as discussed. I added the line "-Djava.library.path=/usr/lib/jni" to the eclipse.ini file I checked the Eclipse help/about/confirguration settings and both of these lines are listed: eclipse.vmargs=-Djava.library.path=/usr/lib/jni java.library.path=/usr/lib/jni I checked that those files are in those directories. Still, when I check the preferencesteamsvn an error dialog shows: Failed to load JavaHL Library. These are the errors that were encountered: no libsvnjavahl.1 in java.library.path Incompatible JavaHL library loaded 1.3.x or later required I followed the "Testing JavaHL libraries" troubleshooting section at the bottom of the wiki: I downloaded the tarbal and ran it in a folder on my desktop with no problems. Then, I followed the instructions and placed that file INSIDE the path (usr/lib/jni/testJavaHL) and ran it from there. There are 50 tests performed and each one of them came back with this same error (posting only one for brevity): 50) testCommitRevprops(org.tigris.subversion.javahl.BasicTests)java.io.FileNotFoundException: /usr/lib/jni/testJavaHL/local_tmp/greek_files/iota (No such file or directory) at java.io.FileOutputStream.open(Native Method) at java.io.FileOutputStream.<init>(FileOutputStream.java:209) at java.io.FileOutputStream.<init>(FileOutputStream.java:160) at org.tigris.subversion.javahl.WC.materialize(WC.java:70) at org.tigris.subversion.javahl.SVNTests.buildGreekFiles(SVNTests.java:303) at org.tigris.subversion.javahl.SVNTests.setUp(SVNTests.java:222) at org.tigris.subversion.javahl.RunTests.main(RunTests.java:111) FAILURES!!! Tests run: 50, Failures: 0, Errors: 50 Any ideas as to how/why the "local_tmp/greek_files/iota" is appended to the directory? I assume that's my problem.. I'm also having a problem with newrepository location = ...as the directory location of my svn repository is one level above the home directory - which is prepended to whatever I place in the dialog box - resulting in this error: svn: '/home/ricalsin/file:/home/svn' does not exist Thank you for any help.

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• Software RAID 1 Configuration

  - by Corve

  I have created a software RAID 1 quite some while ago and it always seemed to work for me. However I am not completely sure that I have configured everything right and do not have the experience to check so I would be very grateful for some advice or just verification that all seems right so far. I am using Linux Fedora 20 (32 bit with plans to upgrade to 64bit) The RAID 1 should consist of two 1TB SATA hard drives. This is the output of mdadm --detail /dev/md0 /dev/md0: Version : 1.2 Creation Time : Sun Jan 29 11:25:18 2012 Raid Level : raid1 Array Size : 976761424 (931.51 GiB 1000.20 GB) Used Dev Size : 976761424 (931.51 GiB 1000.20 GB) Raid Devices : 2 Total Devices : 1 Persistence : Superblock is persistent Update Time : Sat Jun 7 10:38:09 2014 State : clean, degraded Active Devices : 1 Working Devices : 1 Failed Devices : 0 Spare Devices : 0 Name : argo:0 (local to host argo) UUID : 1596d0a1:5806e590:c56d0b27:765e3220 Events : 996387 Number Major Minor RaidDevice State 0 0 0 0 removed 1 8 0 1 active sync /dev/sda The RAID is mounted successfully: friedrich@argo:~ ? sudo mount -l | grep md0 /dev/md0 on /mnt/raid type ext4 (rw,relatime,data=ordered) Basically my question are: Why do I only have 1 active device? What does the State removed at bottom mean? Also I noticed some strange error messages that I see on the console on system start and shutdown and always repeating in the background when I switch with Ctrl + Alt + F2: ... ata2: irq_stat 0x00000040 connection status changed ata2: SError: { CommWake DevExch } ata2: COMRESET failed (errno=-32) ata2: exception Emask 0x10 SAct 0x0 SErr 0x4040000 action 0xe frozen ata2: irq_stat 0x00000040 connection status changed ata2: SError: { CommWake DevExch } ata2: exception Emask 0x10 SAct 0x0 SErr 0x4040000 action 0xe frozen ... Are these errors related to the RAID? Something seems wrong with the SATA devices.. All together the system works (I can read and write to the mounted raid) but I always had these strange errors on startup shutdown (probably always in the background). Thx for your help

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• PC dies when running at 100% CPU

  - by user155631

  I recently wrote some Java code to generate images of the Mandelbrot set (fractal). I made use of the new Fork/Join facility in Java 7 to run separate threads on all four cores (2 real, 2 virtual)simultaneously, using a large number of iterations for greater accuracy. The problem is, the process runs fine for about a minute, and then it's as if someone has pulled the plug and the PC just dies. I thought it must be the CPUs overheating, so I ran Real Temp to monitor the temperature. It's an Intel i3 processor. I can see the temperature creeping up to 70 degrees, and then it seems to level off there and run for about another 30 seconds before dying. According to Real Temp, there's still a gap of 35 degrees between the actual temperature and TJ max. I also tried disabling "CPU TM function" in the BIOS, but the problem still occurs. A colleague suggested that it might be a power supply problem, so I borrowed a more powerful PSU (can't remember what wattage it was, but it's higher than mine which is 500W). The exact same thing still happens though. Is anyone able to suggest what the problem might be, or what I can try next?

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• How can I use wildcards in an Nginx map directive?

  - by Ian Clelland

  I am trying to use Nginx to served cached files produced by a web application, and have spotted a potential problem; that the url-space is wide, and will exceed the Ext3 limit of 32000 subdirectories. I would like to break up the subdirectories, making, say, a two-level filesystem cache. So, where I am currently caching a file at /var/cache/www/arbitrary_directory_name/index.html I would store that instead at something like /var/cache/www/a/r/arbitrary_directory_name/index.html My trouble is that I can't get try_files, or even rewrite to make that mapping. My searching on the subject leads me to believe that I need to do something like this (heavily abbreviated): http { map $request_uri $prefix { /aa* a/a; /ab* a/b; /ac* a/c; ... /zz* z/z; } location / { try_files /var/cache/www/$prefix/$request_uri/index.html @fallback; # or # if (-f /var/cache/www/$prefix/$request_uri/index.html) { # rewrite ^(.*)$ /var/cache/www/$prefix/$1/index.html; # } } } But I can't get the /aa* pattern to match the incoming uri. Without the *, it will match an exact uri, but I can't get it to match just the first two characters. The Nginx documentation suggests that wildcards should be allowed, but I can't see a way to get them to work. Is there a way to do this? Am I missing something simple? Or am I going about this the wrong way?

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• Upgrade SQLServer 2008 hardware

  - by John

  Forgive me if I'm not able to be totally clear here. It is not intentional, I'm a senior level developer in a very small company having to act like a manager at the moment. Anyway, the story is that we have 2 older dell servers with SQL Server 2008 Standard in a "cluster". I put that in quotes because I'm still not 100% clear what that means. We have 2 brand new blade servers and want to move the existing databases to the new hardware. Ok, so here is the gotcha. We need to do this with little or no down time. I'm being told that we can evict the passive node, then pull in one of the new servers. But I'm also being told that this is a dangerous step because something could go wrong that would cause the cluster to fail and then we would be left with nothing because the active server would not be able to come back up. Does anyone have any thoughts on how to handle this? I'm being told that the only way to ensure success is to have at least a day of down time where we bring up a new cluster on the new hardware and then migrate the databases 1 by 1.

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• Steps to deploy a custom routing protocol

  - by user134589

  I'm a Ph.D Student and I'm researching a Service Centric Networking architecture with resourceallocation on a large scale. What I'm looking to do is expand an existing routing protocol like OSPF with extra fields and some new message types that I need for communication between Nodes. I want to manipulate the cost of a network link and I want paths to be calculated like in OSPF V2/v3, but using the cost that my algorithms have calculated. What I have I have the source code of OSPF from Quagga. I am assuming I can edit this code how I want, including packet structures and creating new types. Yes, I am aware it won't be easy but this is a 6 years research project and I am eager to develop something new, to move forward. What I need I would like to know how I can deploy the edited OSPF source files I have (written in C) on any type of server. I have a large testbed environment available with hundreds of virtual nodes and pretty much any OS out there. So if I want to test my extended protocol, how do I make all the nodes in a network use this to communicate? I do not understand what parts of the kernel I need to edit here. I tried searching for days now and I am unable to find how to deploy a non-existing routing protocol, without the use of an application-level framework. If somebody could push me in the right direction that'd be awesome. note: I need this to be a routingprotocol and not an application, since I want this to work on op of the network layer for performance reasons. Thanks!

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• Google Drive terminates without error on startup

  - by Iszi

  I've used Google Drive for awhile now, but it won't start up after installing on my latest system re-build. I'm still using the same OS, hardware, and basic software load (antivirus, firewall, etc.) that I have for years during which I had not previously had problems with Drive. OS: Windows 7 Ultimate x64 Google Drive Version: 1.12.5329.1887 Now, whenever I try to run Google Drive, it just spawns two instances of the executable which die shortly after. No error messages are posted to the desktop, and nothing indicating any problem is written to the Event Log. After some research, I've yet to find anyone having the same problem who's found an answer. I did find out how to run Google Drive in diagnostic mode, using the --vv parameter at the command line. After that, I opened up the sync log and got this: 2013-10-31 17:11:24,039 INFO pid=3664 1892:MainThread logging:1600 OS: Windows/6.1.7601-SP1 2013-10-31 17:11:24,039 INFO pid=3664 1892:MainThread logging:1600 Google Drive (build 1.12.5329.1887) 2013-10-31 17:11:24,039 DEBUG pid=3664 1892:MainThread logging:1608 DEBUGGING DUMP is ON. 2013-10-31 17:11:24,051 ERROR pid=3664 1892:MainThread logging:1575 ERROR, UNEXPECTED EXCEPTION 2013-10-31 17:11:24,051 ERROR pid=3664 1892:MainThread logging:1575 [Error 5] Access is denied Traceback (most recent call last): File "<string>", line 232, in Main File "<string>", line 118, in RegisterCustomFileTypes File "P:\p\agents\hpal4.eem\recipes\353983091\base\b\drb\googleclient\apps\webdrive_sync\windows\build\pyi.win32\main\outPYZ1.pyz/windows.registry", line 62, in GetValue WindowsError: [Error 5] Access is denied 2013-10-31 17:11:24,052 INFO pid=3664 1892:MainThread logging:1600 Crash reporting disabled. Ignoring report. 2013-10-31 17:11:24,052 INFO pid=3664 1892:MainThread logging:1600 Exiting with error code: 0 I'm running on an account with Administrator-level permissions, and have even tried using "Run As Administrator" on the EXE. I'm not sure why it's looking for a P:\ drive, as no such volume has ever been mounted on this system. What should I do to try to further troubleshoot, and resolve, this issue?

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• ext3: maximum recommended partition size / handling large partitions

  - by Hansi

  Hi! I would like to do an encrypted install of Ubuntu on a 2 Terabyte drive (i.e., using LUKS/DMcrypt). In order to not have to type in passwords too often, the partitioning scheme will be 50 GB for / and about 1 TB for /home (and the rest for Windows 7), just for clarity. Even though by now LVM is regarded as being stable, I don't want to bother having more room for errors by introducing unnecessary layers of complexity. For both Ubuntu partitions I want encrypted ext3 with the default blocksize of ext3 (4k?). Thoughts: When I look at most partition schemes here on this site or elsewhere, I usually see at most about 400 or 500 GB partitions (maybe I didn't see enough). There may be different reasons for this, but is reliability an issue here? Are larger ext3 partitions, like about 1 TB, harder to handle for the OS or filesystem driver or at some other level? If I make the partition too large, will it be harder to repair in case of corruptions? Are there some default settings for ext3 that I should change for 1 TB partitions? Question: What maximum partition size for ext3 do you recommend and why? Thanks!

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• Document Map in MS Word 2007 going bonkers

  - by rzlines

  I'm working on a large project report in Microsoft Word 2007 and have been using the document map to generate the index. I have been carefully selecting the headers that need to be added to the document map but I saved the document and opened it up today to work on it - the document map has added whatever it pleases there. This is a temporary fix from a post that I found after extensive searching that works, but when I save and close the document and open it up again I face the same dilemma: I have noticed that when Word stuffs up the document map after opening the file, I can undo this by using the UNDO button. Word calls it ’Autoformat’. I have also fixed a file that has had the document map screwed permanently (i.e saved with it) by selecting all (CTRL+A),selecting the PARAGRAPH drop down menu in the HOME TAB and in the OUTLINE drop down box, selecting ’Body Text’. This removed all the problems and did not seem to affect my outline level paragraph headings. This is also another temporary fix but I have to be on my toes not to let Word auto format at the start of the document. I also can't afford to entirely turn off auto format as I need it. I’ve solved this problem for me. When you open the file, a progress bar at the bottom first says Opening (ESC to Cancel) and then it says Word is formatting the document (ESC to Cancel). If I cancel the second process, TOC fine. No cancelling, TOC screwed. Can anyone work out how to switch off the autoformatting? This is the post in which i found for the temporary fix

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• How do you apply proxy settings per computer instead of per user?

  - by Oliver Salzburg

  So far, I've used a user group policy object utilizing Internet Explorer maintenance to set a proxy for the user in IE. We have now deployed the Enterprise Client (EC) starter group policy to our domain and this policy affects this behavior. The EC group policy uses the policy Make proxy settings per-machine (rather than per-user). This policy describes itself as: This policy is intended to ensure that proxy settings apply uniformly to the same computer and do not vary from user to user. Great! This seems to be an improvement over my previous setup. If you enable this policy, users cannot set user-specific proxy settings. They must use the zones created for all users of the computer. What zones and where do I configure the proxy settings for them? I assumed the policy would simply take the user settings and apply them, but that's not what's happening. Now no proxy server is set at all. So my previous settings obviously no longer have any effect. So far, I've only come up with solutions that involved direct manipulation of the Windows registry. Which is fine, I guess, but the way the proxy is configured for users makes it appear as if there could be a higher level approach.

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• Track kids browsing history even when they know how to clear it manually

  - by Darren Newton

  I have a colleague with two teenage boys (yes, cue cliche's about 'I have this friend see...') He's currently having issues with them browsing pr0n and wants to do a little spying on their browsing (I'm staying clear of the philosophies/ethics on this.) The kids are savvy enough to clear their browsing history when they're done. As I'm his goto for IT he has asked me if there is a way to keep a hold of the browsing history. The family uses Macs, and the kids surf with Safari. I know that browsing history is kept here ~/Library/Safari/History.plist. I figure there should be a way to write either an AppleScript or other script (Python/Ruby/Bash) that can backup this file to a different location (/opt/local/history, etc.) Since the kids know to clear their history when they're done should the file be periodically backed up with something similar to a cron job or something like Hazel? While that could work it seems like it would create a ton of little incremental backups. Or is it possible to 'watch' ~/Library/Safari/History.plist and incrementally add changes to a backup file (saving a diff so to speak) but not lose any data? Any ideas/solutions appreciated. UPDATE/EDIT: Got the word from concerned dad that the oldest uses Firefox on a different PC, so the OpenDNS solution (preferably at the router level) is the best answer so far as it would capture usage for the whole house.

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• Distributed storage and computing

  - by Tim van Elteren

  Dear Serverfault community, After researching a number of distributed file systems for deployment in a production environment with the main purpose of performing both batch and real-time distributed computing I've identified the following list as potential candidates, mainly on maturity, license and support: Ceph Lustre GlusterFS HDFS FhGFS MooseFS XtreemFS The key properties that our system should exhibit: an open source, liberally licensed, yet production ready, e.g. a mature, reliable, community and commercially supported solution; ability to run on commodity hardware, preferably be designed for it; provide high availability of the data with the most focus on reads; high scalability, so operation over multiple data centres, possibly on a global scale; removal of single points of failure with the use of replication and distribution of (meta-)data, e.g. provide fault-tolerance. The sensitivity points that were identified, and resulted in the following questions, are: transparency to the processing layer / application with respect to data locality, e.g. know where data is physically located on a server level, mainly for resource allocation and fast processing, high performance, how can this be accomplished? Do you from experience know what solutions provide this transparency and to what extent? posix compliance, or conformance, is mentioned on the wiki pages of most of the above listed solutions. The question here mainly is, how relevant is support for the posix standard? Hadoop for example isn't posix compliant by design, what are the pro's and con's? what about the difference between synchronous and asynchronous opeartion of a distributed file system. Though a synchronous distributed file system has the preference because of reliability it also imposes certain limitations with respect to scalability. What would be, from your expertise, the way to go on this? I'm looking forward to your replies. Thanks in advance! :) With kind regards, Tim van Elteren

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• How to completely disable IPv6 for loopback interface on RHEL 5.6

  - by Marc D

  I've done lots of research on how to disable IPv6 on RedHat Linux and I have it almost completely disabled. However the loopback interface is still getting an inet6 loopback address (::1/128). I can't find where IPV6 is still enabled for loopback. To disable IPV6 I added the following settings to /etc/sysctl.conf: net.ipv6.conf.default.disable_ipv6=1 net.ipv6.conf.all.disable_ipv6=1 And also added the following line to /etc/sysconfig/network: NETWORKING_IPV6=no After rebooting, the inet6 address is gone from my physical interface (eth0), but is still there for lo: # ip addr show 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000 link/ether 00:50:56:xx:xx:xx brd ff:ff:ff:ff:ff:ff inet 10.x.x.x/21 brd 10.x.x.x scope global eth0 If I manually remove the IPV6 address from loopback and then bounce the interface, it comes back: # ip addr del ::1/128 dev lo # ip addr show lo 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo # ip link set lo down # ip link set lo up # ip addr show lo 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo inet6 ::1/128 scope host valid_lft forever preferred_lft forever I believe IPV6 should be disabled at the kernel level as confirmed by sysctl: # sysctl net.ipv6.conf.lo.disable_ipv6 net.ipv6.conf.lo.disable_ipv6 = 1 Any ideas on what else would cause the loopback interface to get an IPV6 address?

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• CentOS: Init scripts failing to start for some unknown reason

  - by user705142

  I'm running CentOS 6.2 - I've just migrated some applications over to a failover server, and copied their init scripts into /etc/init.d. I've made them executable, added them to chkconfig, with chkconfig -add, set their levels, made sure they're residing in /etc/rc.d/ - made sure I can execute them from rc2.d etc. The permissions are the same on both servers. They're also running in the same order as on the primary server Yet on reboot they don't start. Any ideas? The offenders are these: jetty 0:off 1:off 2:on 3:on 4:on 5:on 6:off smart 0:off 1:off 2:on 3:on 4:on 5:on 6:off /etc/init.d: -rwxr-xr-x. 1 root root 14456 Mar 13 20:21 jetty -rwxrwxrwx. 1 root root 5829 Mar 29 09:58 smart /etc/rc.d/rc3.d lrwxrwxrwx. 1 root root 15 Mar 29 19:21 S99jetty -> ../init.d/jetty lrwxrwxrwx. 1 root root 11 Mar 26 17:12 S99local -> ../rc.local lrwxrwxrwx. 1 root root 15 Mar 29 19:21 S99smart -> ../init.d/smart I've checked, and I'm in run level 3. I've checked their logs, and there's no indication that that they've been started. I can start them manually easily - and other services are starting normally. I'm completely out of ideas really.

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• do I need to create an AD site for VPN network

  - by ykyri

  I have Windows Domain level 2008 R2. There are four GC DC in four different physical locations. I have Kerio-based VPN network for replication and remote administration. Here is how network configured: dc1: local IP: 192.168.0.10 VPN IP: 192.168.1.10 dc2: local IP: 10.10.8.11 VPN IP: 192.168.1.11 dc3: local IP: 10.10.9.12 VPN IP: 192.168.1.12 dc4: local IP: 10.10.10.13 VPN IP: 192.168.1.13 That's simple, replication and all works fine but when running dcdiag on dc3 I have an error: A warning event occurred. EventID: 0x000016AF During the past 4.12 hours there have been 216 connections to this Domain Controller from client machines whose IP addresses don't map to any of the existing sites in the enterprise. <...> The log(s) may contain additional unrelated debugging information. To filter out the needed information, please search for lines which contain text 'NO_CLIENT_SITE:'. The first word after this string is the client name and the second word is the client IP address. Here is netlogon.log lines example: 05/30 12:07:39 DOMAIN.NAME: NO_CLIENT_SITE: dc2 192.168.1.11 05/31 09:52:11 DOMAIN.NAME: NO_CLIENT_SITE: dc4 192.168.1.13 05/31 19:49:31 DOMAIN.NAME: NO_CLIENT_SITE: adm-note 192.168.1.101 07/01 05:16:26 DOMAIN.NAME: NO_CLIENT_SITE: dc1 192.168.1.10 All VPN-joined computers are generates same log line as above. Computer amd-note is for example administrator's notebook, also have VPN. Question is should I add new AD site and bind VPN subnet 192.168.1.0/24 with that site?

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• Server Crash Diagnosis...Are there any 'black box recorder' style programs available.

  - by columbo

  My redhat server is crashing every three weeks or so at 4:15am ish on Sunday mornings. (well it was sundays the last two have been Thursday mornings at 4:15ish) Looking at the logs (mysql, httpd, messages) there are no clues as to why. They just seem to stop. I ran a little script to take memory readings every 15 minutes and it too stops (with normal readings) at this time. The server is remote at a provider so I can only access it via the web. I use Plesk. It appears to be a set job or something that is causing the issue. I can see nothing in crontab. So my question is...has anyone else had this and can offer advice? Failing that. Does any one know of a way to get more detailed logging than that offered by the messages file? I was thinking of a black box style recording program or maybe something as simple as an option somewhere to increase the level of reporting in the messages log. Thanks

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• I have a password protected USB drive with hidden partition, how to convert to normal USB drive?

  - by deddebme

  I have a generic USB drive which has password protection, and I want to stop this password protection mechanism and to use it as a normal 8GB USB drive. I received this USB drive as a gift in Hong Kong, and there was no instruction menu whatsoever, not even the manufacturer name. When I plug the drive in Windows XP, the removable drive comes up as a read only 5.28MB partition with two files. When I try to add or remove any files or formatting it, it will says the drive is write protected. After launching the Login.exe and typed in the password, a 8GB read/writeable partition will be shown, and I'm free to do anything to it. But once after the drive is unplugged and replugged, the same read only partition will still comes out no matter what I did to the hidden partition. Anyone knows about this kind if USB drive? What did the manufacturer do to hide the partition? Is there a way to "low-level" formatting this drive to convert (or revert) it to a normal drive? Before typing in the password: After typing in the password:

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• windows 7 turns off itself everyday at about 9am

  - by Radek

  I was given this comp at work and after a week or so this strange thing started to happen in the middle of doing something :-( It turns off itself at about 9.10am every morning Just once a day and it works fine after it had it little nap. it happens both if the comp was on all night or I turned it off before leaving the office. I tried to swapped the memory as I was told that there was an issue with memory. But moving or removing any memory did not make any difference. I am not aware that I would install any program that could cause that. I installed AVG and set it up to do every day scan about 8am + if restart is needed it requires user confirmation. 'The Software Protection service has stopped' few minutes before it turned off itself but it happened also at other times without the computer turned off. I turned off Windows automatic updates as the first thing when I got the comp configuration Windows 7 Ultimate Intel Core2 Quad Q9550 at 2.8GH, 8GB RAM ST31000528AS Barracuda 7200.12 SATA 3Gb/s 1TB Update Below message are logged when I turn the comp on again. Message 1: The previous system shutdown at 9:08:54 AM on ?6/?29/?2010 was unexpected. Message 2: Level:Critical Source: Kernel Power EventID 41 Task Category (63) The system has rebooted without cleanly shutting down first. This error could be caused if the system stopped responding, crashed, or lost power unexpectedly. Log after manual restart Update 2 (task scheduler)

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