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  • Poor performance on IIS7, only on Windows Server 2008, fine on Windows 7?

    - by user32005
    Hi, I'm new to IIS7 but have experience with other versions. I've been working on an application that works great in a dev environment (as always) but when I push it to a windows server 2008/IIS7 box performance takes a noticeable hit. The dev environment is Windows7/IIS7. The configuration in IIS is the same on the dev box as the server. I've tried all sorts of things to try and find a reason for this but I cant come to any conclusion. I've ruled out database problems on the live box as all data is cached after the first request. I've confirmed this to be true and made sure there is no additional database traffic. I've ruled out network issues with a combination of monitoring requests with fiddler and local debugging on the server. Whenever the code runs on the server there seems to be a performance issue. The server: Intel Core 2 Quad CPU Q6600 @ 2.40ghz with 2gb RAM. I know this is not fantastic but I was expecting it to at least perform as well as my dev environment (which is running much more on a lower spec). The CPU using peaks at under 60%, and memory usage is less than half of the available. I've enabled failed request tracing and most of the time is spent in a custom HttpModule, this module works to handle every request, I cant get any more detail as to what within the module may be causing the problem. Any ideas, I've been pulling my hair out for days now. Thanks

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  • Exceptional slowdown of robocopy copying from VM to DFS array

    - by user1588867
    I've got an old win 2003 VM (VMware) on a blade cluster of VMs that I'm moving a considerable amount of files to our new DFS array. There are two main folders with about 1.7 million and half a million smaller files (letters, memos, and other smaller files) respectively. Total size is ~420 GB and ~100 GB. We're using the gui version of robocopy on the server to copy the files. We had initiated a file copy about a month ago to test the process and found that it was taking around 4 hours for the large file. Now that I'm in the process of actually switching the files over it has been taking 18-20 hours. Nothing has changed on the server side and nothing has changed on the settings of the copy (no logs, 1 retry with a wait of 1 second). Our intent is to shut off the share and force the copy over again to get all the files that have been left out of the copy due to being locked by users. I can't take a 20 hour outage to do that though. Does anyone have any theories about what could be causing such a delay for robocopy compared to previously shorter runs?

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  • Array on servers which receive several hundred GB of data a day

    - by Matthew
    This is hopefully a simple question. Right now we are deploying servers which will serve as data warehouses. I know with raid 5 the best practice is 6 disks per raid 5. However, our plan is to use RAID 10 (both for performance and safety). We have a total of 14 disks (16 actually, but two are being used for OS). Keeping in mind that performance is very much an issue, which is better - doing several raid 1's? Do one large raid 10? One large raid 10 had been our original plan, but I want to see if anyone has any opinions I haven't thought of. Please note: This system was designed for using Raid 1+0, so losing half of the raw storage capacity is not an issue. Sorry i hadn't mentioned that initially. The concern is more whether or not we want to use one large Raid 1+0 containing all 14 disks, or several smaller raid 1+0's and then stripe across them using LVM. I know the best practice for higher raid levels is to never use more than 6 disks in an array.

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  • High memory utilization with firebird + windows server 2008 r2

    - by chesterman
    i have a Windows Server 2008 R2 (64bit) running a 64bit installation of Firebird 2.1.4.18393_0 in a 4GB phisical server. After a while, the task manager show that all memory is used, but the sum of the memory of all process does not stack to the half of the memory. Unfortunally, it's start swapping. Using RAMMAP, i can see that my entire database file is mapped into the memory. This only occours in windows server 2008 r2 and windows 7 64 bit. i can use firebird 32 or 64bit installations, doesn't matter. How can i prevent this? Why this only occours in w2k8r2 and w7? tks in advance ** UPDATE Aparently, this occours by the use of all memory by the file system cache. The microsoft documentations explain that this WAS a issue in windows xp, 2k3, vista and 2k8, but it was solved in 7 and 2k8r2. also adds that this issue is more common in 64bit hosts. (http://support.microsoft.com/kb/976618) there are some tools (DynCache, setcache and the Get/SetSystemFileCacheSize system calls from windows API) that allows me to fix a upper limit to the memory usage by the fscache, but the documentation argues that i should not do this in w2k8r2 because it will severely impact on the overall system performance. anyway, i tried, the performance remained the same shit and the use of the page file remained, although there is now more the 1gb of free memory.

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  • HP tx2510us shuts down without warning, now won't boot, no BIOS codes, screen doesn't light

    - by Tim S
    Hey all, HP tx2150us worked great for a year and a half, rarely it would shut down instead of sleeping. It started running hot sometimes, I installed Win7, worked great, still running hot. Before Xmas, it gave me evidence of video errors - jagged lines, rows missing. That same night, it started rebooting, then it shut off and wouldn't boot. It gave me a BIOS code, I shut it off to look up the code online. When I turned it on again, it won't boot at all. The LEDs all light up, the fan, HD, and optical all spin up, but the screen never lights up and it doesn't try to boot, nor does it blink any BIOS codes. It just acts like it's sleeping, and won't wake up. I suspected heat problems, so I disassembled it, cleaned the crap out of the fan, and reassembled it, breaking the stereo mic connector. Oh well. When I reassembled it, it booted up into Win7 again, but kept shutting down for no discernible reason. After a dozen or so random reboots like that, it is now back to where it was - turns on but doesn't boot or give BIOS codes. The screen never lights, and everything spins up then idles. Any ideas? I really can't afford to buy a new one and I use(d) it to take ALL my notes, that's why I got a tablet in the first place.

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  • Performance experiences for running Windows 7 on a Thin-Client?

    - by Peter Bernier
    Has anyone else tried installing Windows 7 on thin-client hardware? I'd be very interested to hear about other people's experiences and what sort of hardware tweaks they had to do to get it to work. (Yes, I realize this is completely unsupported.. half the fun of playing with machines and beta/RC versions is trying out unsupported scenarios. :) ) I managed to get Windows 7 installed on a modified Wyse 9450 Thin-Client and while the performance isn't great, it is usable, particularly as an RDP workstation. Before installing 7, I added another 256Mb of ram (512 total), a 60G laptop hard-drive and a PCI videocard to the 9450 (this was in order to increase the supported screen resolution). I basically did this in order to see whether or not it was possible to get 7 installed on such minimal hardware, and see what the performance would be. For a 550Mhz processor, I was reasonably impressed. I've been using the machine for RDP for the last couple of days and it actually seems slightly snappier than the default Windows XP embedded install (although this is more likely the result of the extra hardware). I'll be running some more tests later on as I'm curious to see particularl whether the streaming video performance will improve. I'd love to hear about anyone's experiences getting 7 to work on extremely low-powered hardware. Particularly any sort of tweaks that you've discovered in order to increase performance..

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  • Looking for a small, portable, port-mirroring ethernet switch.

    - by user37244
    I recently had a mac go haywire, taking half a minute or more to get www.google.com loaded. Getting its owner to give up the machine for repair was like pulling teeth - they were insisting that it must be something to do with the network, since so much had changed with the local configuration at about the same time their box went haywire. I eventually set up a port mirror to a box that I could remote to so I could show that the mac was only irregularly getting packets onto the network. Demonstrating this faced an additional challenge: the latency of the remote desktop software I was using meant that I had to point to timestamps instead of just the moment the packet flashed up on the screen as my evidence. This particular user was the reason this was so challenging this time around, but I would like to have a box that I can cart from desk to desk to use wireshark on my laptop at any station where I need it. 3com, cisco, netgear, etc. (ad nauseum), all make switches that can be configured for port mirroring, but in my case, the smaller, the better. For the sake of my sanity, I'll probably end up running it off a battery anyway. If my laptop had two ethernet ports, this would be easy. So, whaddya recommand for a device that requires 0 configuration at each powerup (though I'm fine with poking at it for a while to set it up initially.) Small, light, and cheap enough to get it past purchasing? Thanks,

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  • How do I set up dual monitors on Kubuntu 10.04 using the latest nVidia drivers with a 9800M video ca

    - by NoCatharsis
    I'm a Linux newb so please try to keep the lingo low-key. I installed the latest nVidia drivers on my laptop using the 9800M card. The laptop is a Gateway P-7805u and I'm connected to the second monitor using VGA. Also, before installing the nVidia drivers (and just using the basic drivers included with Kubuntu 10.04), basic dual monitor support worked, except I could not enable compositing features for some reason. So I thought the proprietary drivers would fix this. Several issues have arisen since installation: 1) I've clicked through all of the display settings to activate the second screen with absolutely no change. 2) When I try to apply settings and Save Configuration as the nVidia help suggests, I am told that I cannot save to the X.conf file. I assume this is due to innate permissions on my user settings, which I have no idea how to properly configure. 3) I have no idea where to go from here, as most of the fixes I found online involve Linux syntax and verbiage, to which I'm totally clueless after spending over half my life with Windows.

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  • How do I send e-mails with attachments to a Microsoft WebTV user?

    - by Petr 'PePa' Pavel
    my friend uses Microsoft WebTV (e-mail address ends with @webtv.net) and I'd like to send him an e-mail with a picture attached to it. We went through a series of attempts one of which ended up a success, all others a failure. He just can't see my e-mail in his mailbox, when it contains an attachment. E-mails without attachments always go through all right. What seemed to help in the first successful case, was that he added my e-mail address to his address book and my e-mail suddenly showed up. Seemed to have been delivered before but hidden. He kept my address in his address book however, it didn't help with the following trials. He did look into his junk folder, nothing there. I made sure the file name contains no spaces. It's a regular jpeg, named something-like-this.jpg I downsized it to have only about 50k, as I've read somewhere that that's a limit. I actually doubt this piece of information, because I think the successful attempt was larger. webtv.net contains zero information. I watched their video demo for the e-mail client, so I at least know how the user interface looks like. I've never laid my hands on the real thing. I'm an advanced user myself (a programmer) but I can't wrap my mind around this. He on the other hand, is a very technically inexperienced user and because he's half way across the globe, I can't come and look over his shoulder. He doesn't have a computer, afaik there's no way I could see what he sees. Any ideas on how to debug this? Thanks for your time, guys. P.S. I can't tag this "webtv" because such tag doesn't exist yet and my reputation is too low, sorry.

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  • Where do these mysterious DNS lookups come from and why are they slow?

    - by Hongli
    I have recently obtained a new dedicated server which I'm now setting up. It's running on 64-bit Debian 6.0. I have cloned a fairly large git repository (177 MB including working files) onto this server. Switching to a different branch is very very slow. On my laptop it takes 1-2 seconds, on this server it can take half a minute. After some investigation it turns out to be some kind of DNS timeout. Here's an exhibit from strace -s 128 git checkout release: stat("/etc/resolv.conf", {st_mode=S_IFREG|0644, st_size=132, ...}) = 0 socket(PF_INET, SOCK_DGRAM|SOCK_NONBLOCK, IPPROTO_IP) = 5 connect(5, {sa_family=AF_INET, sin_port=htons(53), sin_addr=inet_addr("213.133.99.99")}, 16) = 0 poll([{fd=5, events=POLLOUT}], 1, 0) = 1 ([{fd=5, revents=POLLOUT}]) sendto(5, "\235\333\1\0\0\1\0\0\0\0\0\0\35Debian-60-squeeze-64-minimal\n\17happyponies\3com\0\0\1\0\1", 67, MSG_NOSIGNAL, NULL, 0) = 67 poll([{fd=5, events=POLLIN}], 1, 5000) = 0 (Timeout) This snippet repeats several times per 'git checkout' call. My server's hostname was originally Debian-60-squeeze-64-minimal. I had changed it to shell.happyponies.com by running hostname shell.happyponies.com, editing /etc/hostname and rebooting the server. I don't understand the DNS protocol, but it looks like Git is trying to lookup the IP for Debian-60-squeeze-64-minimal as well as for happyponies.com. Why does Debian-60-squeeze-64-minimal come back even though I've already changed the host name? Why does Git perform DNS lookups at all? Why are these lookups so slow? I've already verified that all DNS servers in /etc/resolv.conf are up and responding slowly, yet Git's own lookups time out. Changing the host name back to Debian-60-squeeze-64-minimal seems to fix the slowness. Basically I just want to fix whatever DNS issues my server has because I'm sure they will cause more problems that just slowing down git checkout. But I'm not sure sure what the problem exactly is and what these symptoms mean.

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  • Java: compile and run hanging at command prompt

    - by dwwilson66
    I'm having an issue that I'm hoping someone can help with. I'm working on netbook running WinXP Pro SP3, 1.6GHz & 1GB of RAM. I've got a relatively simple java program that I'm able to successfully compile and run on other computers (both XP and Win7), so I suspect my code is working fine--I've verified that all computers are running the same version of Java (build 1.7.0_02-b13). For about the past week, I get maybe three or four compiles and runs at the command prompt (running CMD from within WinXp) before I hang with a blinking cursor after keying my command and pressing enter. If I shut down the command prompt window and restart it, I can compile and run the program just fine--again, pointing to an OS/environment issue rather than code. The only system change I've made in the past week is to uninstall a Lexmark printer that I ditched a year ago, and removing/reinstalling Java. Oh, and an automatic Windows update... :\ I've used this netbook successfully for programming classes for the past year and a half. Anyone familiar with this issue and know of some system tweaks to solve it? I suspect that memory may not be getting cleaned up when the java program quits...only when CMD closes, but don't know any tools to troubleshoot. Ideas?

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  • Where did my backup files go? Can they be recovered?

    - by Ken
    I just purchased a Western Digital Essential SE 1TB external hard drive from Best Buy at their recommendation. I then exchanged it for a Toshiba Canvio (I think that was the name). I have a Toshiba Qosmio X505-Q898. The Canvio locked up my computer and rewrote some kind of OS file, and erased all the restore points as well as the system image backup (according to Best Buy) just by plugging it in for the first time. Never even got to the install part or anything -- plugged it in and fried my computer. They spent about an hour and a half on my computer and got it back to a somewhat working condition and gave me access to my files. So now they say I have to back it up using my recovery disk and rewriting my OS. Enter the Essential. Brought it home last night, plugged it in and installed everything. Works perfect, no problems. Backed up everything on it. I unplugged and plugged it twice to make sure that everything was on it. Essential told me it had both the HDD and SSD backed up. So I reinstalled my OS. Plugged the Essential in and everything loads right up. Went to retrieve my files and the Western Digital has nothing on it. It shows all my music, pics, ETC. as still being on my computer and needing to be backed up, but since there are no files on my computer now. Where is this information coming from and where did my files go? It's about 810GB worth of files I've amassed over several years. Is there any way to recover data from this? I plan to contact Western Digital and Best Buy, just thought I would check here too. Any advice will be appreciated as a lot of these files are invaluable to me.

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  • PHP on several servers with session-sharing

    - by Etu
    there's certanly other threads about this, but I have one more question. We are about to scale the website at work to have more than one server. And we need to share the sessions between the servers. We have been looking into different solutions, one in memcached and use Memcached as sessionhandler in PHP. That will probably work. And the idea would be to run memcached on every machine and let all webservers access all other servers memcached servers, and then we have shared sessions between the machines, yay. (we have no resources to setup with sticky-sessions yet, that's a later project. we need this running, and we need this running now. and we will loadbalance with DNS for a starter) But then... If I want to take one server down, say, for maintenance, or a server crashes, or whatever reason. I don't want the users to just loose their sessions and have to start from the beginning... That's why we need some kind of replication, which Memcached does not support. Then I found http://repcached.lab.klab.org/ -- which has multi-master replication of memcached, which is great, and is what I want. But does it work with 2 machines? Say 3, 5, 10? For future scaling. I also looked into redishttp://redis.io/ -- which also seems great, but is a bit more "shaky" with the php-session-handler support, and no multi-master-replication. The thing is that I like to use memcached, but I want to be able to power down one of two boxes without loosing half of the sessions. Any suggestions?

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  • Host ::1 resolves to remote IP

    - by thebuckst0p
    /etc/hosts files usually have this line, ::1 localhost. I thought ::1 was the equivalent of 127.0.0.1/localhost, and from my reading it seems to be the IPv6 version. So I was using it in Apache for firewalling, "Allow from ::1" and it only allowed local. Then suddenly that stopped working, so I pinged ::1 and got a remote IP address. I tracerouted it and it went through my ISP, through some Microsoft server, then another half dozen steps of asterisks... I'm not sure why this would be (the remote IP), but it doesn't seem good. I grep'd my hard drive for the remote IP and it doesn't appear anywhere. Is this some indicator that I'm being hacked, or normal behavior? Maybe my IPv6 settings are wrong? (This is a brand new MacBookPro with Snow Leopard.) Any ideas about this would be great - what is ::1 supposed to be, why would it be remote, should I be worried, how do I get it back to localhost? Thank you!

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  • Mesh Networked servers via vpn

    - by microspino
    I got a design idea and I would like to have some advice from SF about It. I have 5 customers with small real-estate databases. I've built for them a desktop app and now they would like to merge their database to share their data. I don't want to centralize everything in one place nor I want to do maintenance for servers. They told me also, that all of them in their offices, have little servers and maintenance guys available. Although everything seems suitable for web application, I had the idea to experiment something new: Any customer small-server wild be connected to the others in a sort of mesh network without a single point of failure and through VPNs. If one of the servers went down the customers could still connect to their databases from one of the other mesh networked servers instead of from the local one that is down. During normal operations all the servers sync the db with the others through VPNs. I can accept a half-day timing window of NON synched data, in other words, since I don't need real time synchronization, the server don't have to always stay in synch. I can migrate my data over to other Non-Sql technologies like CouchDB or Redis or whatever you suggest. As you can see I don't have a lot of constraints and although I could go with a web application I would like to delegate and decentralize support, data-privacy and management, as more as I can to my customers offices. Is that a crazy idea? Do you know If something similar exist? Which technology would you suggest?

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  • Some of my keys are automatically being pressed along with other keys

    - by Santosh
    History The last time when my computer shutdown was a power failure. Now some keys are automatically being pressed when I type something. The last thing I did to keyboard setting was adding a keyboard layout (on Ubuntu). What is happening Whenever I press c, xc is writeen s gives me sd d gives me sd e gives me we 2 gives me 23, So when I want @ it gives me @# 3 gives me 23 Pressing CAPS Lock gives me F3 and vice-versa. All other key are either working fine or I don't use them. I have two operating system Ubuntu and Windows, I use Windows very less and found this problem on Ubuntu, but as soon as I logged in to Windows (for checking) then I found that Windows has the same problem. Effects on my life This starts form the time of login, even I have problem in typing my password. Whenever I try to save any webpage, it is bookmarked automatically. Whenever I copy, it is cut automatically. I have to spend more than half of time correcting what I have typed. Note: Typing thisd quwesdtion wasd rweally a big pain to mwe.

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  • Load is 0, yet site crawls (sometimes). What gives?

    - by Yegor
    I have a ~1.5-2mil page views per day site running on 2 servers. One for mysql, other for everything else. Mysql box has a load of 3, frontend is usually 0.0-0.1. Both are dual quad core with 8GB ram running SAS drives in raid5. CPU is idle for majority of the time, iowait is non-existent. Im running nginx, memcache, and site is built on php. Half the time everything runs perfect, while at other times it lags something severe, when it takes 10-15 seconds for a page to load. Page execution time is always super low, but it seems to hang, waiting for something before it actually loads the page. Whats even more weird is that it only happens to 1 file on the site (but its the one thats most commonly accessed, that actually loads the content on the site). Other pages are super fast at all times, even when it takes 15 seconds to load actual content. I have nginx_stats plugin installed, and if I monitor it, the lag spikes happen when the write column starts going above 100, and it frequently does... all the way to 500-1000. It does so at totally random times... not when traffic is heavy... it can do this in the middle of the night, and work perfectly at 5pm when traffic is at its highest. Any ideas?

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  • Why am I missing 4GB of RAM on Windows Server 2008 R2 64bit?

    - by Nick G
    I noticed today that a server was very low on memory. It physically has 8GB installed and runs Windows 2008 R2 Standard 64bit. It also hosts 2 virtual machines using HyperV. Server is Dell Poweredge R510. However the host OS reports in task manager that it only has 4GB of RAM, despite actually having 8GB and it being a 64bit OS. Computer properties shows Installed memory: 8.00GB (3.99GB usuable). Why would "usable" be half the real RAM installed under a 64bit OS? Additionally nearly all of the 4GB of visible RAM on the host OS is being used by something without anything showing up in task manager (presumably HyperV as it's allocated 3.6GB to the virtual machines its hosting). However that doesn't explain where the other 4GB has gone which Windows can't even see. Where is my missing 4GB of RAM? Update: Dell OpenManage says this: Total Installed Capacity 8192 MB Total Installed Capacity Available to the OS 4096 MB So looks like Nathan's suggestion of memory mirroring might be correct. I'll have to reboot to check this (I think?) Update 2 OK. So I reboot and I get a message saying "the amount of system memory has changed" (despite not having touched the hardware in a year). Once Windows has booted, all 8GB is visible again. Looks like I probably have a hardware RAM issue (I'll perhaps try reseating it whenever I can chuck everyone off the server next). Thanks for your answers and comments. I was hoping it was going to be the mirrored-RAM option but it seems not - that's not even mentioned in the BIOS.

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  • ubuntu's average load never below "0.00 0.01 0.05"

    - by Karma Fusebox
    I have several ubuntu 12.04 VMs running on a ubuntu 12.04 KVM host. Those of the virtual machines that are totally idle with no services (except syslog and the other "small" standard stuff of a fresh installation) show a constant load of "0.00 0.01 0.05" in top/htop as average 1/5/15. When there are "real" applications running, the load averages behave perfectly normal but they never fall below the mentioned values. While this doesn't affect performance at all and could easily be ignored, it screws up the monitoring graphs in a very annoying way: (Notice how load15 behaves nicely if 0.05 for a short time in the right half of the pic) Unfortunately I don't know what diagnostic outputs might be helpful for you, so here's some default stuff: # top top - 16:31:01 up 1:05, 1 user, load average: 0.00, 0.01, 0.05 Tasks: 62 total, 1 running, 61 sleeping, 0 stopped, 0 zombie Cpu(s): 0.2%us, 0.2%sy, 0.0%ni, 99.2%id, 0.5%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 1019464k total, 73452k used, 946012k free, 6140k buffers Swap: 0k total, 0k used, 0k free, 22504k cached . # free -m total used free shared buffers cached Mem: 995 72 923 0 6 21 -/+ buffers/cache: 43 951 Swap: 0 0 0 . # iostat -x /dev/vda Linux 3.2.0-32-virtual (vm3) 11/15/2012 _x86_64_ (2 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 0.25 0.00 0.65 0.20 0.24 98.66 Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util vda 0.14 0.12 0.51 0.22 6.74 1.46 22.50 0.02 23.26 20.64 29.30 7.63 0.56 Need something else? Has anyone ever seen this behavior? Might this be a bug in kvm/ubuntu/kernel 3.x in the end? Thanks a lot!

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  • How to eliminate the domain suffix off my user profile folder when migrating to a new domain?

    - by Jerry Dodge
    We have just upgraded a decade old SBS 2003 server to a brand new SBS 2011 machine. During the process, over 30 other client/server machines on that domain also needed to be dis-joined and re-joined from the old domain to the new one. These domains have different names and is not migrated in any way. It's built from scratch. Since each client machine had very unique user profiles under this domain, we needed to make sure these were all backed up and migrated over to the new domain. For the most part, profiles were migrated with no hassle, just by renaming the user profile folder names. However, in one case, when I log in to my domain account, it creates a profile folder with a suffix of the new domain name. I have replaced all the files in the profile's root which begin with "ntuser" with the files of the new profile. The only problem is half the applications can't find their data, because the folder name is different. How can I change this folder name and maintain this profile on the new domain? I have deleted every user account (except admin), deleted their profiles/folders, removed them from the registry, and made sure every trace of this account was gone. The computer was basically a dummy with only an admin account. Then, I log into the machine under my new domain user account (same username as the old domain). It creates a profile folder with my username plus a suffix extension of the new domain name. The client machine is Windows 7 Ultimate, the old server was SBS 2003, and the new server is SBS 2011.

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  • Linux iptables / conntrack performance issue

    - by tim
    I have a test-setup in the lab with 4 machines: 2 old P4 machines (t1, t2) 1 Xeon 5420 DP 2.5 GHz 8 GB RAM (t3) Intel e1000 1 Xeon 5420 DP 2.5 GHz 8 GB RAM (t4) Intel e1000 to test linux firewall performance since we got bitten by a number of syn-flood attacks in the last months. All machines run Ubuntu 12.04 64bit. t1, t2, t3 are interconnected through an 1GB/s switch, t4 is connected to t3 via an extra interface. So t3 simulates the firewall, t4 is the target, t1,t2 play the attackers generating a packetstorm thorugh (192.168.4.199 is t4): hping3 -I eth1 --rand-source --syn --flood 192.168.4.199 -p 80 t4 drops all incoming packets to avoid confusion with gateways, performance issues of t4 etc. I watch the packet stats in iptraf. I have configured the firewall (t3) as follows: stock 3.2.0-31-generic #50-Ubuntu SMP kernel rhash_entries=33554432 as kernel parameter sysctl as follows: net.ipv4.ip_forward = 1 net.ipv4.route.gc_elasticity = 2 net.ipv4.route.gc_timeout = 1 net.ipv4.route.gc_interval = 5 net.ipv4.route.gc_min_interval_ms = 500 net.ipv4.route.gc_thresh = 2000000 net.ipv4.route.max_size = 20000000 (I have tweaked a lot to keep t3 running when t1+t2 are sending as many packets as possible). The result of this efforts are somewhat odd: t1+t2 manage to send each about 200k packets/s. t4 in the best case sees aroung 200k in total so half of the packets are lost. t3 is nearly unusable on console though packets are flowing through it (high numbers of soft-irqs) the route cache garbage collector is no way near to being predictable and in the default setting overwhelmed by very few packets/s (<50k packets/s) activating stateful iptables rules makes the packet rate arriving on t4 drop to around 100k packets/s, efectively losing more than 75% of the packets And this - here is my main concern - with two old P4 machines sending as many packets as they can - which means nearly everyone on the net should be capable of this. So here goes my question: Did I overlook some importand point in the config or in my test setup? Are there any alternatives for building firewall system especially on smp systems?

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  • Redis connection issue

    - by mre
    We are currently experiencing a lot of Redis errors with the message Unable to connect: read error on connection, trying next server We run Redis on FreeBSD using PHP Redis and we have a hard time reproducing the error on Ubuntu so this might be a hint. There's a long-running issue on that topic on github. Basically we get a socket from the operating system with a call to connect(host, port, timeout) in phpredis, but when we do a select(db_index) afterwards, we get an exception. Could there be an issue with persistance? I assume that connect does nothing in the background and select tries to access the connection, which is actually closed. We don't run into a timeout. We tried tuning TIME_WAIT without success. Any other ideas on where the problem might come from? What is the best way to track the issue down? dtrace maybe? Update We are currently looking into our BGSAVE settings. Interestingly it takes half a second and more to create a fork for the process which regularly writes the data to disk (persistence) and maybe redis can't respond to connect() requests during that timespan.

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  • Windows Server 2008 IIS Random disconnect

    - by d123
    I am having a bit of a quirk with my IIS server. I'm running my IIS with 2 sets of IPs configured, one in the 192 range and the other in 172 range. I then have multiple apps which will talk to this server for information. Server has no AV or firewalls configured. I noticed that my apps when talking to the server on the 172 range, at random intervals, the server would just not respond. My apps would then disconnect and just try again, and every thing would be fine. This doesn't happen on the 192 range. So what I did is on a Linux box I did a watch command and to wget a file every half second on the 172 and 192 IPs. I noticed the same issue, every once in awhile wget on the 172 range would not get through, but there is no issues at all on 192. Thus I went around to Wireshark and did a dump. This is the last 3 packets, no other packets were received. 7010 100.871877 200.100.30.7 172.0.0.1 TCP 59619 http [ACK] Seq=140 Ack=85242 Win=64128 Len=0 TSV=1072818795 TSER=1660246133 7011 100.872238 200.100.30.7 172.0.0.1 TCP 59619 http [FIN, ACK] Seq=140 Ack=85242 Win=64128 Len=0 TSV=1072818796 TSER=1660246133 7013 100.873081 200.100.30.7 172.0.0.1 TCP 59619 http [ACK] Seq=141 Ack=85243 Win=64128 Len=0 TSV=1072818796 TSER=1660246133 So this is my issue, there is a random disconnect every once in awhile. The server doesn't receive the next SYN packet. HELP?

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  • Looking for advice on using dd to backup a dual boot laptop.

    - by AvatarOfChronos
    My questions boils down to this. If I do "dd if=/dev/sda of=usbdrive" can anybody confirm that this will get everything including mbr/partition information/all four partitions and create a drive that I can swap with the failing internal drive without losing anything? If this is done while the computer is running will it still copy everything? At this point I'm afraid to shutdown the computer for fear of it never starting again. Secondly, how tolerant is dd of failing drives? Has anybody used it to recover a half dead drive before that can share any potential pitfalls? Did it get the data ok or is this going to be a hope for the best kind of situation? And lastly, If the usbdrive is larger than the failing internal drive I'll still be able to expand the partitions later so I'm not losing space? this last part seems silly to ask but with my current streak of bad luck I'll end up overwriting some magic bit and forever turning a 640gb hdd into a 500gb hdd. Also if anybody has a better solution to create a complete clone that gets everything I'm all for hearing about it. PostScript: I had been making periodic backups however when whatever miasma that killed the laptop struck it also got the NAS :( Post PostScript: both devices were on a UPS system.

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  • Fresh install CentOS 6.4 64b with directadmin slowly consumes all memory and crashes

    - by Coen Ponsen
    Dear server fault community, This is my first question on server fault, i'm new to server (mis)configuration so please forgive me for asking something stupid :) I'm running Directadmin on a CentOS 6.4 64b with 4GB memory and over 10000Gh virtual machine. I migrated my websites because my former vps couldn't keep up anymore. Only half of the websites from this 1GB machine were migrated jet. So the migration is still in progress and already my server crashes every day. The server performance up until that moment is perfect. The directadmin log files show nothing out of the ordinary. Yesterday only the mysql server crashed but it also crashed the entire machine before. The memory usage in DA seems to be normal: directadmin directadmin (pid 3923 22158 22159 22160 22161 22162 )8.75 MB dovecot dovecot (pid 3851 ) 47.8 MB exim exim (pid 1350 ) 1.29 MB httpd (pid 21525 21528 21529 21530 21531 21532 21546 21571 21742 21743 21744 )490.4 MB mysqld mysqld (pid 1299 ) 287.8 MB named named (pid 3807 ) 16.3 MB proftpd proftpd (pid 1481 ) 1.91 MB sshd sshd (pid 1173 21494 ) 5.16 MB Restarting services immediately frees up memory, but slowly over time the memory usage increases(about 24 hours to crash). The commands: # sync # echo 3 > /proc/sys/vm/drop_caches Will free al memory correct. I could just create a cronjob but it seems the wrong way around to me. I can't seem to pinpoint the cause. Any advices, references or tips are highly appreciated! Greetings, Coen edit: free -m : after drop_caches: total used free shared buffers cached Mem: 3830 735 3095 0 0 21 -/+ buffers/cache: 712 3117 Swap: 991 0 991 I'll post another one this evening.

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