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• Seeking (somewhat) better explanations about supporting > 2.1 TB hard drives.

  - by irrational John

  Today while Googling about I stumbled across posts claiming that Seagate plans to ship a 3TB drive sometime later in 2010. Unfortunately, the stuff I looked at all seemed to contain tidbits of info which I didn't think fit together properly. (I would link to some examples, but I'm only allowed 1 link per post at the moment). Now I really don't have any "need" to better understand the underlying tedious details of this. I am just curious. And confused. So ... some questions I'm hoping someone better informed than I might answer. The talk about a potential addressing problem in both the hardware and the software confused me. The assertion is that something called something called Long LBA addressing (LLBA) is needed in the Command Descriptor Block as a way to get around the current limits to access a hard drive bigger than ~2.1 (or ~2.2?) TB. OK, fine. But I thought the last time this problem came up it was solved by extending the length of the LBA field from 28 to 48 bits. (Remember this website? www.48bitlba.com) A 6 byte LBA is clearly large enough, so what's up with this LLBA talk. I thought this was all fixed back by Win XP SP2, if not sooner? And certainly all the hardware should be up to the task, shouldn't it? The real problem as I understand it with drives much bigger than 2 TB are the 4 byte LBA fields in the Master Boot Record (MBR) used to partition just about all hard drives at the moment. The most likely solution is to migrate to Intel's GUID Partition Table (GPT). A GPT uses 8 byte fields for the LBA. What I don't understand in this context is what is the problem with booting say Windows from a 3TB drive that uses a GPT. Granted, the current PC BIOS wouldn't know how to recognize or work with a GPT. But every GPT comes with a so-called "Safety" or "Guarding" MBR in sector 0.Apple already uses a hybrid version of the MBR to allow them to boot Windows on their Intel Macs (aka Boot Camp). Couldn't something similar be done to allow the PC BIOS to recognize and boot from a partition in, say, the first 1 GB of a 3GB or larger drive? I've got more questions such as where do 4K sectors fit into all of this. But it's probably time I just shut up and posted this. ;-) -irrational john

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• IIS6 Virtual Directory 500 Error on Remote Share

  - by David Boike

  We have our servers at the server farm in a domain. Let's call it LIVE. Our developer computers live in a completely separate corporate domain, miles and miles away. Let's call it CORP. We have a large central storage unit (unix) that houses images and other media needed by many webservers in the server farm. The IIS application pools run as (let's say) LIVE\MediaUser and use those credentials to connect to a central storage share as a virtual directory, retrieve the images, and serve them as if they were local on each server. The problem is in development. On my development machine. I log in as CORP\MyName. My IIS 6 application pool runs as Network Service. I can't run it as a user from the LIVE domain because my machine isn't (and can not be) joined to that domain. I try to create a virtual directory, point it to the same network directory, click Connect As, uncheck the "Always use the authenticated user's credentials when validating access to the network directory" checkbox so that I can enter the login info, enter the credentails for LIVE\MediaUser, click OK, verify the password, etc. This doesn't work. I get "HTTP Error 500 - Internal server error" from IIS. The IIS log file reports sc-status = 500, sc-substatus = 16, and sc-win32-status = 1326. The documentation says this means "UNC authorization credentials are incorrect" and the Win32 status means "Logon failure: unknown user name or bad password." This would be all and good if it were anywhere close to accurate. I double- and trouble-checked it. Tried multiple known good logins. The IIS manager allows me to view the file tree in its window, it's only the browser that kicks me out. I even tried going to the virtual directory's Directory Security tab, and under Authentication and Access Control, I tried using the same LIVE domain username for the anonymous access credential. No luck. I'm not trying to run any ASP, ASP.NET, or other dynamic anything out of the virtual directory. I just want IIS to be able to load static images, css, and js files. If anyone has some bright ideas I would be most appreciative!

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• load-causing processes disappearing from "top" ps -o pcpu shows bogus numbers

  - by Alec Matusis

  I administer a large number of servers, and I have this problem only with Ubuntu 10.04 LTS: I run a server under normal load (say load average 3.0 on an 8-core server). The "top" command shows processes taking certain % of CPU that cause this load average: say PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 11008 mysql 20 0 25.9g 22g 5496 S 67 76.0 643539:38 mysqld ps -o pcpu,pid -p11008 %CPU PID 53.1 11008 , everything is consistent. The all of the sudden, the process causing the load average disappears from "top", but the process continues to run normally (albeit with a slight performance decrease), and the system load average becomes somewhat higher. The output of ps -o pcpu becomes bogus: # ps -o pcpu,pid -p11008 %CPU PID 317910278 1587 This happened to at least 5 different severs (different brand new IBM System X hardware), each running different software: one httpd 2.2, one mysqld 5.1, and one Twisted Python TCP servers. Each time the kernel was between 2.6.32-32-server and 2.6.32-40-server. I updated some machines to 2.6.32-41-server, and it has not happened on those yet, but the bug is rare (once every 60 days or so). This is from an affected machine: top - 10:39:06 up 73 days, 17:57, 3 users, load average: 6.62, 5.60, 5.34 Tasks: 207 total, 2 running, 205 sleeping, 0 stopped, 0 zombie Cpu(s): 11.4%us, 18.0%sy, 0.0%ni, 66.3%id, 4.3%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 74341464k total, 71985004k used, 2356460k free, 236456k buffers Swap: 3906552k total, 328k used, 3906224k free, 24838212k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 805 root 20 0 0 0 0 S 3 0.0 1493:09 fct0-worker 982 root 20 0 0 0 0 S 1 0.0 111:35.05 fioa-data-groom 914 root 20 0 0 0 0 S 0 0.0 884:42.71 fct1-worker 1068 root 20 0 19364 1496 1060 R 0 0.0 0:00.02 top Nothing causing high load is showing on top, but I have two highly loaded mysqld instances on it, that suddenly show crazy %CPU: #ps -o pcpu,pid,cmd -p1587 %CPU PID CMD 317713124 1587 /nail/encap/mysql-5.1.60/libexec/mysqld and #ps -o pcpu,pid,cmd -p1624 %CPU PID CMD 2802 1624 /nail/encap/mysql-5.1.60/libexec/mysqld Here are the numbers from # cat /proc/1587/stat 1587 (mysqld) S 1212 1088 1088 0 -1 4202752 14307313 0 162 0 85773299069 4611685932654088833 0 0 20 0 52 0 3549 27255418880 5483524 18446744073709551615 4194304 11111617 140733749236976 140733749235984 8858659 0 552967 4102 26345 18446744073709551615 0 0 17 5 0 0 0 0 0 the 14th and 15th numbers according to man proc are supposed to be utime %lu Amount of time that this process has been scheduled in user mode, measured in clock ticks (divide by sysconf(_SC_CLK_TCK). This includes guest time, guest_time (time spent running a virtual CPU, see below), so that applications that are not aware of the guest time field do not lose that time from their calculations. stime %lu Amount of time that this process has been scheduled in kernel mode, measured in clock ticks (divide by sysconf(_SC_CLK_TCK). On a normal server, these numbers are advancing, every time I check the /proc/PID/stat. On a buggy server, these numbers are stuck at a ridiculously high value like 4611685932654088833, and it's not changing. Has anyone encountered this bug?

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• Windows Service Limit Crashes Services on Startup

  - by Paul Williams

  We have developed a custom Windows service in C# as part of a large Enterprise application. Our QA department tests multiple versions of this service. The QA lab has several (over 20) copies of this service installed on one Windows 2003 test box. Each copy is in its own folder and has a unique service name, though each executable file is named the same (OurWindowsService.exe, for example). Each service uses the same Windows credentials (a domain user). The purpose of this service is to handle MSMQ messages. The queued messages do all sorts of important stuff. For some reason, they can run only 5 of these services at a time. When we start a 6th, the service crashes on startup. For example, I can start #1, #2, #3, #4, and #5. When I start #6, it crashes. However, if I stop #1 and start #6, #6 runs fine, and now #1 fails to start. When the services crash, the following error appears in the Windows event log: Faulting application OurWindowsService.exe, version 5.40.1.1, faulting module kernel32.dll, version 5.2.3790.4480, fault address 0x0000bef7. I was able to use WinDbg to generate a postmortem dump file. The dump file revealed that the crash occurs trying to delay load SHLWAPI.dll: 0:000> kb100 ChildEBP RetAddr Args to Child 0012ece4 79037966 c06d007e 00000000 00000001 KERNEL32!RaiseException+0x53 0012ed4c 790099ba 00000008 0012ed08 7c82860c mscoree!__delayLoadHelper2+0x139 0012ed98 790075b1 001550c8 0012edac 0012fb34 mscoree!_tailMerge_**SHLWAPI_dll**+0xd 0012edb0 79007623 001550c8 0012edf8 0012edf4 mscoree!XMLGetVersionWithSupported+0x22 0012ee00 790069a4 aa06f1b0 00000000 000001fe mscoree!RuntimeRequest::GetRuntimeVersion+0x56 0012f478 790077aa 00000001 7903fb4c 0012fb34 mscoree!RuntimeRequest::ComputeVersionString+0x5bd 0012f89c 79007802 00000001 0012f8b4 7903fb4c mscoree!RuntimeRequest::FindVersionedRuntime+0x11c 0012f8b8 79007b19 00000001 00000000 aa06fa6c mscoree!RuntimeRequest::RequestRuntimeDll+0x2c 0012ffa4 79007c02 00000001 0012ffbc 00000000 mscoree!GetInstallation+0x72 0012ffc0 77e6f23b 00000000 00000000 7ffdf000 mscoree!_CorExeMain+0x12 0012fff0 00000000 79007bf0 00000000 78746341 KERNEL32!BaseProcessStart+0x23 I believe the error code handed to Kernel32.RaiseException, c06d007e, means Module Not Found, but I'm not certain. Does this sound familiar to anyone? Are we hitting some limit on the number of service instances on some file name? Does MSMQ dislike more than 5 listening services?

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• Adaptec 5805 not recognized after reboot

  - by Rakedko ShotGuns

  After rebooting the system, the controller is not recognized. It only works if the computer is shut down and turned off. I have recently updated the firmware to "Adaptec RAID 5805 Firmware Build 18948". How do I fix the problem? Configuration summary --------------------------- 1. Server name.....................raid_test Adaptec Storage Manager agent...7.31.00 (18856) Adaptec Storage Manager console.7.31.00 (18856) Number of controllers...........1 Operating system................Windows Configuration information for controller 1 ------------------------------------------------------- Type............................Controller Model...........................Adaptec 5805 Controller number...............1 Physical slot...................2 Installed memory size...........512 MB Serial number...................8C4510C6C9E Boot ROM........................5.2-0 (18948) Firmware........................5.2-0 (18948) Device driver...................5.2-0 (16119) Controller status...............Optimal Battery status..................Charging Battery temperature.............Normal Battery charge amount (%).......37 Estimated charge remaining......0 days, 16 hours, 12 minutes Background consistency check....Disabled Copy back.......................Disabled Controller temperature..........Normal (40C / 104F) Default logical drive task priority High Performance mode................Dynamic Number of logical devices.......1 Number of hot-spare drives......0 Number of ready drives..........0 Number of drive(s) assigned to MaxCache cache0 Maximum drives allowed for MaxCache cache8 MaxCache Read Cache Pool Size...0 GB NCQ status......................Enabled Stay awake status...............Disabled Internal drive spinup limit.....0 External drive spinup limit.....0 Phy 0...........................No device attached Phy 1...........................No device attached Phy 2...........................No device attached Phy 3...........................1.50 Gb/s Phy 4...........................No device attached Phy 5...........................No device attached Phy 6...........................No device attached Phy 7...........................No device attached Statistics version..............2.0 SSD Cache size..................0 Pages on fetch list.............0 Fetch list candidates...........0 Candidate replacements..........0 69319...........................31293 Logical device..................0 Logical device name............. RAID level......................Simple volume Data space......................148,916 GB Date created....................09/19/2012 Interface type..................Serial ATA State...........................Optimal Read-cache mode.................Enabled Preferred MaxCache read cache settingEnabled Actual MaxCache read cache setting Disabled Write-cache mode................Enabled (write-back) Write-cache setting.............Enabled (write-back) Partitioned.....................Yes Protected by hot spare..........No Bootable........................Yes Bad stripes.....................No Power Status....................Disabled Power State.....................Active Reduce RPM timer................Never Power off timer.................Never Verify timer....................Never Segment 0.......................Present: controller 1, connector 0, device 0, S/N 9RX3KZMT Overall host IOs................99075 Overall MB......................4411203 DRAM cache hits.................71929 SSD cache hits..................0 Uncached IOs....................29239 Overall disk failures...........0 DRAM cache full hits............71929 DRAM cache fetch / flush wait...0 DRAM cache hybrid reads.........3476 DRAM cache flushes..............-- Read hits.......................0 Write hits......................0 Valid Pages.....................0 Updates on writes...............0 Invalidations by large writes...0 Invalidations by R/W balance....0 Invalidations by replacement....0 Invalidations by other..........0 Page Fetches....................0 0...............................0 73..............................10822 8...............................3 46138...........................4916 27184...........................15226 20875...........................323 16982...........................1771 1563............................5317 1948............................2969 Serial attached SCSI ----------------------- Type............................Disk drive Vendor..........................Unknown Model...........................ST3160815AS Serial Number...................9RX3KZMT Firmware level..................3.AAD Reported channel................0 Reported SCSI device ID.........0 Interface type..................Serial ATA Size............................149,05 GB Negotiated transfer speed.......1.50 Gb/s State...........................Optimal S.M.A.R.T. error................No Write-cache mode................Write back Hardware errors.................0 Medium errors...................0 Parity errors...................0 Link failures...................0 Aborted commands................0 S.M.A.R.T. warnings.............0 Solid-state disk (non-spinning).false MaxCache cache capable..........false MaxCache cache assigned.........false NCQ status......................Enabled Phy 0...........................1.50 Gb/s Power State.....................Full rpm Supported power states..........Full rpm, Powered off 0x01............................113 0x03............................98 0x04............................99 0x05............................100 0x07............................83 0x09............................75 0x0A............................100 0x0C............................99 0xBB............................100 0xBD............................100 0xBE............................61 0xC2............................39 0xC3............................69 0xC5............................100 0xC6............................100 0xC7............................200 0xC8............................100 0xCA............................100 Aborted commands................0 Link failures...................0 Medium errors...................0 Parity errors...................0 Hardware errors.................0 SMART errors....................0 End of the configuration information for controller 1

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• How much did it cost our competitor to DDoS us at 50 Gbps for two weeks?

  - by MiniQuark

  I know that this question may sound like an invalid serverfault question, but I believe that it's quite valid: the amount of time and effort that a sysadmin should spend on DDoS protection is a direct function of typical DDoS prices. Let me rephrase this: protecting a web site against small attacks is one thing, but resisting 50 Gbps of UDP flood is another and requires time & money. Deciding whether or not to spend that time & money depends on whether such an attack is likely or not, and this in turn depends on how cheap and simple such an attack is for the attacker. So here's the full story: our company has been victim to a massive DDoS attack (over 50 Gbps of UDP traffic, full-time during 2 weeks). We are pretty sure that it's one of our competitors, and we actually know which one, because we were the only two remaining competitors on a very big request for proposal, and the DDoS attack magically stopped the day we won (double hurray, by the way)! These people have proved in the past that they are very dishonest, but we know that they are not technical at all, so we believe that they simply paid for some botnet DDoS service. I would like to know how much these services typically cost, for such a large scale attack. Please do not give any link to such services, I would really hate to give these people any publicity. I understand that a hacker could very well do this for free, but what's a typical price for such an attack if our competitors paid for it through some kind of botnet service? It is really starting to scare me (if we're talking thousands of dollars here, then I am really going to freak off: who knows, they might just hire a hit-man one day?). Of course we filed a complaint, but the police says that they cannot do much about it (DDoS attacks are virtually untraceable, so they say), and our suspicions are not enough to justify them raiding our competitor's offices to search for proofs. For your information, we now changed our infrastructure to be able to sustain such attacks: we now use a major CDN service so that our servers are not directly affected by DDoS attacks. Requests for dynamic pages do get proxied to our servers, but for low level attacks (UDP flood, or Syn floods, for example) we only receive legitimate trafic, so we're fine. If they decide to launch higher level attacks (HTTP flood or slowloris attacks for example), most of the load should be handled by the CDN... at least I hope so! Thank you very much for your help.

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• Media Archive System with branches?

  - by Ian McEwen

  In short, how can I get VCS features (revisioning, branching, and deduplication) for a media collection that's far too large for most/all VCS systems? Background I have a 300GB music folder; unfortunately, I only have the hard drive space for this on my desktop system. However, a good portion of my collection is FLAC; therefore, I could theoretically have a space-optimized version in which I transcode all the FLAC to mp3 or some other lossy format, and use only that version on the laptop. However, a portion of my collection isn't FLAC. And that which isn't FLAC shouldn't be transcoded to an equivalent format; it won't have any space savings, which is the point. Moreover, it shouldn't be duplicated: the mp3/ogg portions of the collection should probably be exactly the same files. Thoughts One solution is to have format-specific organization of my music folders, and use some script to transcode the FLAC directory to mp3 or such into another directory. Another is some sort of hack using entirely separate copies and symbolic links for deduplication, or something similar. But these also have a disadvantage of lacking versioning; I'd like to be able to reorganize my music collection, retag things, etc. and save history. This isn't key, but would be awfully nice. I can't see it as entirely unreasonable to set up VCS hooks or something equivalent to keep directory structure synced between two copies, update tags, and transcode FLAC automatically into the space-optimized copy. Basically, the system I really want is a version control system. Two branches: one archival/desktop branch including the FLAC, one space-optimized/laptop branch without it; most VCSes would deal well with whole chunks being the same files well by compressing in a reasonable way (i.e. don't keep two copies of the same data). I could also do a lot of what I talk about above with hooks. But I don't know of any VCS that would deal with a 300GB repository with almost 20k files. Many of them would just not even initialize the whole affair; others would just do it inexpressibly slowly or otherwise badly. checkpoint looks like it's designed for something close (it's at least for media), but wouldn't do deduplication well (and I'm not convinced I'd be able to script it to do things like automatic transcoding and directory-structure syncing). So. Is there anything out there that can do all this, or should I consider it a programming project?

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• Impact of the L3 cache on performance - worth a dual-processor system?

  - by Dan Nissenbaum

  I will be purchasing a new high-end system, and I would like to have a better sense of whether a dual-processor Xeon system (I am looking at the new, high-end Xeon E5-2687W) might, realistically, provide a noticeable performance improvement due to the doubling of the L3 cache (20 MB per CPU). (This is in addition to the occasional added advantage due to the doubling of cores and RAM.) My usage scenario is, roughly, that I have many background applications running at any time - 3 or 4 data compression/backup applications, a low-impact web server, one or two virtual machines at any given time (usually fairly idle), and perhaps 20 utility programs that utilize a noticeable (but small) portion of the CPU cores. In total, when I am not actively using the computer, about 25% of the total CPU power is utilized in my current i7-970 6-core (12 thread) system. When I am doing routine work, the CPU utilization often exceeds 50%, and occasionally hits 75%-80%. The Xeon E5-2687W is not only a second-generation i7 (so should improve performance for that reason), but also has 8 cores (16 threads), rather than 6 cores. For this reason, I expect to run into the 75% CPU range even less frequently. Nonetheless, the ability to double the cores and the RAM is a consideration. However, in the end, I believe this decision comes down to whether the doubling of the L3 cache will provide a noticeable improvement. There are many benchmarks, and a lot of discussion, regarding CPU power. However, I find very little discussion of L3 cache utilization, and how increases in the L3 cache (such as doubling it with dual processors) affect performance. For example: If there are only two processes running, but each benefits from a large L3 cache (such as might be the case for background processes that frequently scan the file system), perhaps the overall system performance might noticeably improve with dual CPU's - even if only a single core is active on each CPU - due to each process having double the effective L3 cache. I am hoping that someone has a sense of the benefits of increasing (or doubling) the L3 cache size. Note: the CPU I am considering (the Xeon E5-2687W) has 20 MB L3 cache, so a system with dual CPU's would have 40 MB L3 cache.

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• Transient network dropout for Xen DomU's

  - by Stephen C

  We've got a CentOS server running a cluster of virtuals. Occasionally the cluster's internal network drops out for a minute or so ... and then comes back. The problem is somehow related to the actual network traffic, but it is not a simple load issue. (The system is generally lightly loaded, and the problem occurs irrespective of actual load.) The setup: CentOS 5.6 on Dom0, various CentOS on the DomU's Hardware - a Dell R710 with a BroadCom NextXpress 2 NIC (sigh) using the latest drivers for the NIC from BroadCom Xen configured to use network-bridge and vif-bridge Some iptable tweaks to route an unrelated port to one of the virtuals. The system has one externally visible IP address, and Dom0 runs an Apache httpd configured with a number of virtual hosts each of which reverse proxies to web servers running on the virtuals. (The virtuals have to be NAT'ed, primarily because we don't have enough allocated public IP addresses.) The symptoms: Works fine most of the time. When someone tries to UPLOAD a large file to one virtuals, the internal network drops out ... for all virtuals: The Dom0 httpd sees a network timeout talking to the backend server on the virtual and reports a 502. A previously established ssh connection from Dom0 to any of the DomU's freezes. Our monitoring shows ping failures for traffic between virtuals. The Xen consoles to the DomU's do not freeze. No log messages in any log files that I can see, on either Dom0 or the DomU's ... apart from the Dom0 httpd logs. After a minute or so, the problem clears by itself. This is 100% reproducible. What we've tried: Downloading, building and installing the latest BNX2 driver on Dom0 Turning off MSI on the NIC - adding "options bnx2 disable_msi=1" to /etc/modprobe.conf Turning off tcp segmentation offload - "ethtool -K eth0 tso off". Sacrificing a black rooster at midnight. I've exhausted all my options apart from switching to KVM ... or slaughtering more roosters. Any suggestions?

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• Loss of wireless network connectivity when playing video via HDMI cable

  - by Jeff Fohl

  Hi Folks - New to Super User, so I hope this question fits in with the guidelines. Very strange problem I am having, and I am at a loss as to how to continue troubleshooting this one. The basic problem is that when I attempt to watch streamed video on a particular display device (an Optoma HD180 projector), my network connectivity drops like a stone to barely measurable levels. This is my setup: I have a Dell H2C 730x running Windows 7 64bit. This particular computer has two ATI Radeon HD 4800 video cards. I have two Samsung 22" monitors connected to one card, and an Optoma HD180 digital projector connected to the other card via an HDMI cable. My internet connection is normally a reliable 6Mbps. The problem I am having occurs when I stream video (or even just browse the web) on the Optoma Projector. When I do this, my internet connection drops to practically zero (just a few kilobits per second). When I move the browser away from the projector, and over to one of my Samsung monitors, the internet connection comes right back. Note that the Optoma projector is on and enabled as a third monitor all this time. I can move the mouse around on the projector without triggering the problem. I tried pinging my router when I was playing a movie on one of the monitors, and I get a 1 millisecond response. However, when I have the movie playing on the Optoma projecter, pinging the router gives me response times in the hundreds of milliseconds, or times out completely. So, it clearly is something local to my machine - and not some sort of throttling occurring down the line. I would think that it is possibly something to do with the HDMI driver conflicting somehow with my network driver (which is a USB-based wireless connection). This one has me really stumped. Anyone have any ideas? EDIT: I am now leaning towards the possibility that the HDMI cable is somehow interfering with the wireless network, when large amounts of data are being pushed through the cable. Is this possible?

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• Broadcom HT1100 SATA controller not working properly with 1TB drives

  - by Jeff C

  I've been using RHEL distro's for several years and always managed to find the answers until now. I know this is more of a hardware issue, but I've been working on this for over a week and trust Linux and the IT community to help more then HP. I have CentOS 6.3 installed on an HP ProLiant DL145 G3 server with the BroadCom HT1100 IO controller and ServerWorks SATA Controller MMIO BIOS v3.0.0015.6 Firmware. This controller does not support large drives fully. Here's what I've tried and the results; Stock setup - Freezes on the ServerWorks POST screen. Can't even enter CMOS without disconnecting the drives. If I simply disconnect the SATA cables before it gets to the ServerWorks screen and reconnect afterwards I can boot from a CD, USB, PXE fine. However fiddling with cables at ever boot isn't practical. If I enter the BIOS config I can set it to not try booting the drives but leave the controller enabled. This lets me boot normally but the drives are not visible in the OS (live CDs or USB installed). I used method #2 to install and update CentOS. I have the /boot partition on a USB drive (everything else is on the SATA drives in software RAID1) hoping that would work around the issue but I get this Kernel panic - not syncing:Attempted to kill init! Pid: 1, comm: init Not tainted 2.6.32-279.9.1.el6.x86_6 #1 Call Trace: [<ffffffff814fd6ba>] ? panic+0xa0/0x168 [<ffffffff81070c22>] ? do_exit+0x862/0x870 [<ffffffff8117cdb5>] ? fput+0x25/0x30 [<ffffffff81070c88>] ? do_group_exit+0x58/0xd0 [<ffffffff81070d17>] ? sys_exit_group+0x17/0x20 [<ffffffff8100b0f2>] ? system_call_fastpath+0x16/0x1b panic occured, switching back to text console I'm sure it should be possible to talk to the drives without the BIOS boot check since the BIOS doesn't see them in method #2 either, their disconnected when it checks, but Linux sees them fine. If anyone could help figure out how I would greatly appreciate it! The other possible option I've come across is a complex firmware update. Tyan has a few boards on their website with the HT1100 and a ServerWorks v3.0.0015.7 update which says "adds support for TB drives" in the release notes. If someone could help me get the Tyan SATA firmware into the HP ROM file so I could just reflash that would also be very much appreciated. Thanks for any help you guys can offer!

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• Switch flooding when bonding interfaces in Linux

  - by John Philips

  +--------+ | Host A | +----+---+ | eth0 (AA:AA:AA:AA:AA:AA) | | +----+-----+ | Switch 1 | (layer2/3) +----+-----+ | +----+-----+ | Switch 2 | +----+-----+ | +----------+----------+ +-------------------------+ Switch 3 +-------------------------+ | +----+-----------+----+ | | | | | | | | | | eth0 (B0:B0:B0:B0:B0:B0) | | eth4 (B4:B4:B4:B4:B4:B4) | | +----+-----------+----+ | | | Host B | | | +----+-----------+----+ | | eth1 (B1:B1:B1:B1:B1:B1) | | eth5 (B5:B5:B5:B5:B5:B5) | | | | | | | | | +------------------------------+ +------------------------------+ Topology overview Host A has a single NIC. Host B has four NICs which are bonded using the balance-alb mode. Both hosts run RHEL 6.0, and both are on the same IPv4 subnet. Traffic analysis Host A is sending data to Host B using some SQL database application. Traffic from Host A to Host B: The source int/MAC is eth0/AA:AA:AA:AA:AA:AA, the destination int/MAC is eth5/B5:B5:B5:B5:B5:B5. Traffic from Host B to Host A: The source int/MAC is eth0/B0:B0:B0:B0:B0:B0, the destination int/MAC is eth0/AA:AA:AA:AA:AA:AA. Once the TCP connection has been established, Host B sends no further frames out eth5. The MAC address of eth5 expires from the bridge tables of both Switch 1 & Switch 2. Switch 1 continues to receive frames from Host A which are destined for B5:B5:B5:B5:B5:B5. Because Switch 1 and Switch 2 no longer have bridge table entries for B5:B5:B5:B5:B5:B5, they flood the frames out all ports on the same VLAN (except for the one it came in on, of course). Reproduce If you ping Host B from a workstation which is connected to either Switch 1 or 2, B5:B5:B5:B5:B5:B5 re-enters the bridge tables and the flooding stops. After five minutes (the default bridge table timeout), flooding resumes. Question It is clear that on Host B, frames arrive on eth5 and exit out eth0. This seems ok as that's what the Linux bonding algorithm is designed to do - balance incoming and outgoing traffic. But since the switch stops receiving frames with the source MAC of eth5, it gets timed out of the bridge table, resulting in flooding. Is this normal? Why aren't any more frames originating from eth5? Is it because there is simply no other traffic going on (the only connection is a single large data transfer from Host A)? I've researched this for a long time and haven't found an answer. Documentation states that no switch changes are necessary when using mode 6 of the Linux interface bonding (balance-alb). Is this behavior occurring because Host B doesn't send any further packets out of eth5, whereas in normal circumstances it's expected that it would? One solution is to setup a cron job which pings Host B to keep the bridge table entries from timing out, but that seems like a dirty hack.

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• Dell PowerEdge R720 - Corrupted RAID

  - by BT643

  Apologies in advance for the lengthy question. We have a Dell PowerEdge R720 server with: 2 x 136GB SAS drives in RAID 1 for the OS (Ubuntu Server 12.04) 6 x 3TB SATA drives in RAID 5 for data A few days ago we were getting errors when trying to access files on the large RAID 5 partition. We rebooted the server and got a message about the raid controller has found a foriegn config. We've had this before, and just needed to use Dell's RAID configuration utility to import foreign config on the RAID. Last time this worked, but this time, it started doing a disk check then we got this: FSCK has returned the following: "/dev/sdb1 inode 364738 has a bad extended attribute block 7 /dev/sdb1 unexpected inconsistency run fsck manually (i.e without -a or -p options) MOUNTALL fsck /ourdatapartition [1019] terminated with status 4 MOUNTALL filesystem has errors /ourdatapartition errors where found while checking the disk drive for /ourdatapartition Press F to fix errors, I to Ignore or M for Manual Recovery" We pressed F to try and fix the errors, but it eventually errored with: Inode 275841084, i_blocks is 167080, should be 0. Fix? yes Inode 275841141 has an invalid extend node (blk 2206761006, lblk 0) Clear? yes Inode 275841141, i_blocks is 227872, should be 0. Fix? yes Inode 275842303 has an invalid extend node (blk 2206760975, lblk 0) Clear? yes .... Error storing directory block information (inode=275906766, block=0, num=2699516178): Memory allocation failed /dev/sdb1: ***** FILE SYSTEM WAS MODIFIED ***** e2fsck: aborted /dev/sdb1: ***** FILE SYSTEM WAS MODIFIED ***** mountall: fsck /ourdatapartition [1286] terminated with status 9 mountall: Unrecoverable fsck error: /ourdatapartition We noticed one of the drive lights was not lit at all, and thought this may have failed and be the problem. We replaced the drive with a spare, and tried "F" to repair it again, but we keep just getting the same error as above. In the RAID configuration utility, all drives show as "online" and "optimal". We do have this data on another replicated server, so we're not worried about "recovering" anything, we just want to get the system back online asap. The server has 64 or 32GB memory, can't remember off the top of my head, but either way, with a 14TB RAID, I think it may still not be enough. Thanks EDIT - I checked the memory usage while fsck was running as suggested and after 2 or 3 minutes, it looked like this, using up nearly all of our servers memory: When it failed after 5 minutes or so with the error in my post, the memory immediately freed up again:

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• What the best way to achieve RPO of zero and lowest possible RTO (less than 15 minutes) with SQL 2008 R2?

  - by Adrian Hope-Bailie

  We are running a payments (EFT transaction processing) application which is processing high volumes of transactions 24/7 and are currently investigating a better way of doing DB replication to our disaster recovery site. Our current and previous strategies have included using both DoubleTake and Redgate to replicate data to a warm stand-by. DoubleTake is the supported solution from the payments software vendor however their (DoubleTake's) support in South Africa is very poor. We had a few issues and simply couldn't ever resolve them so we had to give up on DoubleTake. We have been using Redgate to manually read the data from the primary site (via queries) and write to the DR site but this is: A bad solution Getting the software vendor hot and bothered whenever we have support issues as it has a tendency to interfere with the payment application which is very DB intensive. We recently upgraded the whole system to run on SQL 2008 R2 Enterprise which means we should probably be looking at using some of the built-in replication features. The server has 2 fairly large databases with a mixture of tables containing highly volatile transactional data and pretty static configuration data. Replication would be done over a WAN link to a separate physical site and needs to achieve the following objectives. RPO: Zero loss - This is transactional data with financial impact so we can't lose anything. RTO: Tending to zero - The business depends on our ability to process transactions every minute we are down we are losing money I have looked at a few of the other questions/answers but none meet our case exactly: SQL Server 2008 failover strategy - Log shipping or replication? How to achieve the following RTO & RPO with logshipping only using SQL Server? What is the best of two approaches to achieve DB Replication? My current thinking is that we should use mirroring but I am concerned that for RPO:0 we will need to do delayed commits and this could impact the performance of the primary DB which is not an option. Our current DR process is to: Stop incoming traffic to the primary site and allow all in-flight transaction to complete. Allow the replication to DR to complete. Change network routing to route to DR site. Start all applications and services on the secondary site (Ideally we can change this to a warmer stand-by whereby the applications are already running but not processing any transactions). In other words the DR database needs to, as quickly as possible, catch up with primary and be ready for processing as the new primary. We would then need to be able to reverse this when we are ready to switch back. Is there a better option than mirroring (should we be doing log-shipping too) and can anyone suggest other considerations that we should keep in mind?

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• Can't Move Windows to 2nd Monitor without Left Mouse and Cntl Key

  - by John C

  I have 2 very frustrating problems that maybe someone can help me with: I have 2 monitors (different sizes and resolutions) setup with the "Extended" monitor Win7 setup. My problem is this = I can not "move" a window from my Primary Monitor (larger and higher resolution on right side in front of me) to my Secondary 2nd monitor (smaller and lower resolution) with just selecting the title bar with the left mouse button and dragging it to the left. Windows 7 "snaps" it back to the left Primary Monitor when the window is physically in the 2nd window area as I'm holding the left mouse button. I can prevent this problem - by holding down the Cntl Key with the Left Mouse button, but this is extremely annoying to me. Also I typically "lose" focus if I try typing input on the 2nd monitor. Typing is erratic with regard to keystroke accuracy from my keyboard translated into input on the 2nd screen. No problem with typing input on the primary left monitor. I find this extremely annoying in Windows 7 and turning off the "snap" feature via the Control panel does NOT work for me. Win7 stubbornly refuses to move my selected window to my 2nd monitor without me "forcing" Win7 to do this with the Cntrl Key. Please tell me this is not a Win7 feature. Also on my system - Windows Key + Shift, Left arrow Key (pressed together) or the same combo with The Right arrow Key - don't do anything whatsoever. Widows Key with "+" however does maximize current window across both monitors, and I can "restore" it with Windows Key and "-" back to original monitor and size. I have tried various solutions including changing the resolutions of one or both of my monitors and sometimes "temporarily helps" but reverts back to the problem. Also if I swap the logical (not physical) layout so that I tell Win7 the monitors are setup in a reserved situation (Large monitor on the left, and small on the right) - this also sometimes helps for awhile - and is very strange and awkward to work with "backwards". But all of these solutions stop working. The only solution that consistently works for "moving" the screens is to hold the Cntrl Key down as I'm moving window with the left mouse selected on the title bar. Even that however, doesn't prevent the loss of typing focus for me on the 2nd monitor - while at the same time the typing on the 1st monitor is fine. Any help on moving my window screens from one monitor on my 2nd monitor without having to press the Cntrl key while holding down my left mouse button with be appreciated. Also any help on gaining typing "focus" into my 2nd screen with be helpful too. Thanks - John

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• Why does writing a file to an NFS share send a COMMIT operation to the NFS server?

  - by Antonis Christofides

  I have a Debian squeeze (2.6.32-5-amd64) which is at the same time a NFS4 server and client (it mounts itself through NFS4). The local directory that leads directly to disk is /nfs4exports/mydir, whereas /nfs4mounts/mydir is the same thing mounted through NFS, using the machine's external IP address. Here is the line from fstab: 192.168.1.75:/mydir /nfs4mounts/mydir nfs4 soft 0 0 I have an application that writes many small files. If I write directly to /nfs4exports/mydir, it writes thousands of files per second; but if I write to /nfs4mounts/mydir, it writes 4 files per second or so. I can greatly increase speed if I add async to /etc/exports. (Writing a single large file to the NFS-mounted directory goes at more than 100 MB/s.) I examine the server statistics and I see that whenever a file is written, it is "committed" (this also happens with NFSv3): root@debianvboxtest:~# mount -t nfs4 192.168.1.75:/mydir /mnt root@debianvboxtest:~# nfsstat|grep -A 2 'nfs v4 operations' Server nfs v4 operations: op0-unused op1-unused op2-future access close commit 0 0% 0 0% 0 0% 10 4% 1 0% 1 0% root@debianvboxtest:~# echo 'hello' >/mnt/test1056 root@debianvboxtest:~# nfsstat|grep -A 2 'nfs v4 operations' Server nfs v4 operations: op0-unused op1-unused op2-future access close commit 0 0% 0 0% 0 0% 11 4% 2 0% 2 0% Now in the RFC, I read this: The COMMIT operation is similar in operation and semantics to the POSIX fsync(2) system call that synchronizes a file's state with the disk (file data and metadata is flushed to disk or stable storage). COMMIT performs the same operation for a client, flushing any unsynchronized data and metadata on the server to the server's disk or stable storage for the specified file. I don't understand why the client commits. I don't think that the "echo" shell built-in command runs fsync; if echo wrote to a local file and then the machine went down, the file might be lost. In contrast, the NFS client appears to be sending a COMMIT upon completion of the echo. Why? I am reluctant to use the async NFS server option, because it would apparently ignore COMMIT. I feel as if I had a local filesystem and I had to choose between syncing every file upon close and ignoring fsync altogether. What have I understood wrong?

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• SQL Server database filled the hard drive and freeing up space isn't possible

  - by Jon

  I have a database in SQL Server 2008 on a 1Tb hard drive and it filled the drive, there is only 4Kb free. The MDF file is 323Gb and the LDF is 653Gb. The hard disk this DB is on has no other files on it other than the MDF and LDF so it's impossible to free up any space on the drive. The main hard disk is smaller but there is enough room to transfer the MDF to that drive, in case that helps. This server is overseas at a customer site and it's not possible at the moment to add more disk space to the server. It's also not possible to delete any records because the DB is in a failed mode (due to no disk space) and it doesn't respond to most commands. The Db is currently in full recovery mode which is why the LDF file is so large. This DB really doesn't need to be in full recovery so going forward we plan on switching it to simple mode which will save us a lot of space. I also don't care about losing the LDF file, but I need all of the data. I've spent a lot of time looking for a way out of this problem but everything I've found first involves either freeing up disk space or adding more disk space, neither of which is an option at this time. I'm stuck and any help would be greatly appreciated. I get the following log when trying to switch the DB to online mode. Msg 945, Level 14, State 2, Line 3 Database 'DBNAME' cannot be opened due to inaccessible files or insufficient memory or disk space. See the SQL Server errorlog for details. Msg 5069, Level 16, State 1, Line 3 ALTER DATABASE statement failed. Msg 1101, Level 17, State 12, Line 3 Could not allocate a new page for database 'DBNAME' because of insufficient disk space in filegroup 'DEFAULT'. Create the necessary space by dropping objects in the filegroup, adding additional files to the filegroup, or setting autogrowth on for existing files in the filegroup. I've found the following solutions but none work due to having no disk space on that drive, and since the DB is in a failed state I can't run most commmands. - DBCC SHRINKFILE - can't be run because doing a 'use DBNAME' fails - Detaching the DB and then changing the location of the MDF/LDF files, this fails because the DB is in an offline mode so you can't run detach. I'm at a loss about what else to try. Thanks.

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• Clamdscan scans file in 0 seconds

  - by SupaCoco

  I have to run clamav on large files. I was wondering which command was the fastest between clamscan and clamdscan. But it seems that clamdscan is not working properly: it scans file larger than 1 GB. Could you guys help me find why the heck clamdscan isn't working ? Between clamscan and clamdscan which one is less resource consuming ? I run ClamAV 0.97.8/18037 on Ubuntu 12.04.3 LTS. Please find below the execution result of both commands: clamscan myfile.zip ----------- SCAN SUMMARY ----------- Known viruses: 2864504 Engine version: 0.97.8 Scanned directories: 0 Scanned files: 1 Infected files: 0 Data scanned: 0.00 MB Data read: 1024.16 MB (ratio 0.00:1) Time: 9.145 sec (0 m 9 s) clamdscan myfile.zip /home/ubuntu/workspace/benchmark/myfile.zip: OK ----------- SCAN SUMMARY ----------- Infected files: 0 Time: 0.000 sec (0 m 0 s) And here are the clamav log file: Wed Oct 30 10:26:32 2013 -> Received POLLIN|POLLHUP on fd 4 Wed Oct 30 10:26:32 2013 -> Got new connection, FD 9 Wed Oct 30 10:26:32 2013 -> Received POLLIN|POLLHUP on fd 5 Wed Oct 30 10:26:32 2013 -> fds_poll_recv: timeout after 5 seconds Wed Oct 30 10:26:32 2013 -> Received POLLIN|POLLHUP on fd 9 Wed Oct 30 10:26:32 2013 -> got command CONTSCAN /home/ubuntu/workspace/benchmark/myfile.zip (51, 7), argument: /home/ubuntu/workspace/benchmark/myfile.zip Wed Oct 30 10:26:32 2013 -> mode -> MODE_WAITREPLY Wed Oct 30 10:26:32 2013 -> Breaking command loop, mode is no longer MODE_COMMAND Wed Oct 30 10:26:32 2013 -> Consumed entire command Wed Oct 30 10:26:32 2013 -> Number of file descriptors polled: 1 fds Wed Oct 30 10:26:32 2013 -> fds_poll_recv: timeout after 3600 seconds Wed Oct 30 10:26:32 2013 -> THRMGR: queue (single) crossed low threshold -> signaling Wed Oct 30 10:26:32 2013 -> THRMGR: queue (bulk) crossed low threshold -> signaling Wed Oct 30 10:26:32 2013 -> /home/ubuntu/workspace/benchmark/myfile.zip: OK Wed Oct 30 10:26:32 2013 -> Finished scanthread Wed Oct 30 10:26:32 2013 -> Scanthread: connection shut down (FD 9) Wed Oct 30 10:26:32 2013 -> THRMGR: queue (single) crossed low threshold -> signaling Wed Oct 30 10:26:32 2013 -> THRMGR: queue (bulk) crossed low threshold -> signaling

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• Triple (3) Monitors under Linux

  - by widgisoft

  I have a 3 monitor setup (each 1680x1050) via an Nvidia NVS440 (2 GPUs, 2 outputs per GPU totalling 4 outputs); this works fine under Windows XP,7 but caused considerable headaches under Linux (Ubuntu 9.04). I had previously used an XFX 9600GT and the onboard XFX 9300GS to produce the same result but the card was noisy and power hungry and I was hoping that there was some magical switch in the NVS4400 that got rid of this annoying problem - turns out the NVS440 is just 2 cards on one physical PCB :-p (I searched the net high and low for people using this card under Linux but found nothing, if anything the card uses less power and is fan less so I was to benefit from it either way) Anyway, using either set up there were 5 solutions available: Have 3 separate X instances, all un joined Have 3 separate X instances, adjoined by Xinerama Have 2 separate X instances - One using twin-view, both adjoined by Xinerama Have 2 separate X instances - One using twin-view but no Xinerama Have a single Twin-view setup and leave the 3rd screen unplugged :-p The 4rd option, using 2 separate X instances and twinview (but no xinerama) was the best balance in terms of performance and usability but caused 2 really annoying issues You couldn't control (without altering the shortcuts) which screen an application opened onto - and once it was opened you couldn't move it to another screen without opening up terminal and forcing it to move Nvidia's overriding or falsifying of Xinerama breaks and the 2 screens joined by Twin view behave like a single huge screen causing popups to open in the middle of both screens and maximising of windows stretches to the width of the first 2 screens Firefox can only run one instance as the same user so having multiple firefox windows requires at least 2 users The second option "feels" like the right option, but OpenGL is basically disabled and playing any sort of game or even running anything graphical causes a huge performance drop and instability - even trying to run a basic emulator for gba or gens just causes the system to fall over. It works just enough to stare at your desktop and do nothing but as soon as you start doing some work - opening windows, dragging things around - running multiple copies of firefox it just really feels slow. The last open, only going dual screen works perfectly and everything performs as required, full GPU acceleration - two logical screen spaces - perfect, just make it work across GPUs like windows! :-p Anyway, I know RandR was supposed to pick up the slack when it would introduced GPU objects of sorts to allow multiple GPUs to be stitched together to create one huge desktop at a much deeper layer than Xinerama. I was wondering if this has now been fixed (I noticed X server 1.7 is out) and whether anyone has got it running successfully? Again, my requirements are: One huge desktop to drag any window across Maximising of windows to each screen (as XP does) Running fullscreen apps on the primary screen and disabling the mouse from moving onto the others or on all 3 stretched Finally as a side note; I am aware of the Matrox triple (and dual) head splitter but even the price they go for on eBay is more than I can afford atm, my argument: I shouldn't have to buy extra hardware to get something to work on Linux when it's something that's existed in the windows world for a long time (can you tell I don't get on with X :-p); If I had the cash I'd have bought the latest version of this box already (the new version finally supports large resolutions as the displays I have 1680x1050 each).

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• How can I remove old log entries from a log file and archive them somewhere else in Linux?

  - by Mike B

  CentOS 4.x I apologize in advance if this is not the appropriate place to ask this question. It pertains to a linux server / IT admin task. I've got a log file on an old CentOS 4.x server and I want to remove log entries older than a certain date and place them in a new file for archive. Here's an example of the log format: 2012-06-07 22:32:01,289 ABC:0|Foo|Foo2|4.4|1234|Some Event|123|blah blah blah 2012-06-07 22:32:03,289 ABC:0|Foo|Foo2|4.4|1234|Some Event|123|blah blah blah 2012-06-07 22:32:04,289 ABC:0|Foo|Foo2|4.4|1234|Some Event|123| 2012-06-07 22:32:10,289 ABC:0|Foo|Foo2|4.4|1234|Some Event|123|blah blah blah 2012-06-07 22:32:12,289 ABC:0|Foo|Foo2|4.4|1234|Some Event|123|blah blah blah 2012-06-07 22:32:15,289 ABC:0|Foo|Foo2|4.4|1234|Some Event|123| 2012-06-07 22:32:40,289 ABC:0|Foo|Foo2|4.4|1234|Some Event|123|blah blah blah 2012-06-07 22:32:58,289 ABC:0|Foo|Foo2|4.4|1234|Some Event|123|blah blah blah 2012-06-07 22:33:01,289 ABC:0|Foo|Foo2|4.4|1234|Some Event|123| 2012-06-07 22:33:01,289 ABC:0|Foo|Foo2|4.4|1234|Some Event|123|blah blah blah 2012-06-07 22:33:02,289 ABC:0|Foo|Foo2|4.4|1234|Some Event|123| Essentially, I'm looking for a one-liner that will do the following: Find any events older than a provided YYYY-MM-DD and remove them from the primary log file. Take the deleted events from step 1 and put them in a new log file (Optional) Compress the new archive log file holding the deleted events. I'm aware that there are log rotate tools that do this but this should just be a one-time task so I'd prefer not to set that up. Additional notes: If the date part it tricky or too resource intensive, an alternative would be to just keep the last X number of lines and move the rest. I was originally thinking of something like tail -n 10000 > newfile.txt but that would mean moving the "good" logs to a new file and then doing a name swap... and then I'd still need to remove the "good" entries from the archive. This particular log file is pretty large (1 GB) so I'd prefer the task to be as resource and time efficient as possible. The extra pipes in the log concern me and I'm not sure if I'd need extra protection in the commands to avoid that from causing problems.

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• Be your own cloud [closed]

  - by Jedi

  I have reasonably many electronic gadgets that can go LAN or WI-FI. But how do you share and/or syncronize all your files among them? Well, between my laptops and my desktop I use Dropbox. A nice way to share files among computers. But what if your HDD on your laptop is not large enough to carry music, pictures and films. Normally you would buy an extern USB HDD and store them there, but then you cannot reach the files from other computers which are not connected to the USB device. Many would say I should use a solution like a cloud with a disc station or something like that. But my needs are follows: A mass storage which can be reached among devices (laptops, desktops, iPhone, Android phone, XBox or Playstation). Has low power requirements and is silent. Can be reached inside home and it would be nice if it could be reached outside home as well. Cheap I have looked around and I have found an wireless router which can share a USB device: D-Link Wireless N HD Media Router. I thought it would be an interesting solution for a simple local cloud solution. D-Link uses a little program called SharePort Plus which mount the USB device to your computer. Unfortunately is the transfer rate to the USB storage device rather disappointing. The transfer rate was 5.8 Mbps even though the distance between the laptop and the router was 2 meter. The same is happening when I use cable from the computer to the router. Another thing is that SharePort Plus only allows one computer be connected to the device at a time. The last thing was something I could live with. I have search on the Internet for other solutions and found this video from Synology. I'm not sure if their solution is the right one. I think a disc station connected to my home LAN could the right solution. What have you done in your home to store and share files among your computers and game consoles?

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• How do you backup 40+ Centos5.5 servers?

  - by John Little

  We are embarrassed to ask this question. Apologies for our lack of UNIX expertise. We have inherited 40+ centos 5.5 servers, and don't know how to back them up. We need low level clone type images so that we could restore the servers from scratch if we had to replace the HDs etc. We have used the "dd" command, but we assume this only works if you want to back up one local disk to another, not 40 servers to one server with an external USB HD attached. All 40 servers have a pair of mirrored disks (dont know if its HW or SW raid). Most only have 100MB used. SErvers are running apache, zend, tomcat, mysql etc. Ideally we dont want to have to shut them down to backup (but could). We assume that standard unix commands like tar, cpio, rsync, scp etc. are of no use as they only copy files, not partitions, all attributes, groups etc. i.e. do not produce a result which can simply be re-imaged to a new HD to get the serer back from dead. We have a large SAN, a spare windows box and spare unix boxes, but these are only visible to one layer in the network. We have an unused Dell DL2000 monster tape unit, but no sw or documentation for it. WE have a copy of symantec backup exec, but we have no budget for unix client licenses. (The company has negative amounts of money). We need to be able to initiate the backup remotely, as we can only access the servers in person in an emergency (i.e. to restore) Googling returns some applications to do this, e.g. clonezilla - looks difficult to install and invasive. Mondo, only seems to support backup if you are local to the machine. Amanda might be an option, but looks like days/weeks of work to learn and setup? Is there anything built into Centos, or do we have to go the route of installing, learning and configuring a set of backup softwares? Any ideas? This must be a pretty standard problem which goggling doesnt give an obvious answer.

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• D-Link DIR-300 slows down / loses network

  - by basic6

  there are 2 buildings (A and B). In bldg A is an open WLAN (which I'm allowed to use btw). In bldg B is a computer that I want to connect to that network. So I flashed an old D-Link DIR-300 AP with DD-WRT, mounted it to the wall (bldg B) near a window, attached a 13 dBi directional antenna (pointing to bldg A) and configured it as AP client in that wireless network. Then there's another AP, connected to the D-Link AP, acting as standard access point, which the computer is connected to. That's basically working so far, but: Every now and then the connection is lost. Not the connection between the computer and the D-Link (I can access the DD-WRT admin page normally) or the connection between the D-Link and the WLAN (in Status - Wireless it says it's still connected to the network), but when I want to access a web page (which only works if I'm connected to the wireless network from bldg A), my Firefox keeps "Looking for" (name resolution) without finding anything. When I reset the D-Link (power off, power on) in this situation, after some moments, everything's working fine again (Internet access). I've no idea why this is happening, but usually it's at most every few weeks (most times when nobody was using the computer, so no traffic). Compared to the connection speed when I connect directly to the WLAN in bldg A (Laptop), the speed in bldg B is rather slow, but I have the impression that this difference is worse in the last few days. A few minutes ago, I got 582 KB/s down and 911 KB/s up in bldg A (directly/laptop) and 84 KB/s down and 9 KB/s up in bldg B. The speed in bldg B used to be way higher (I remember 200 KB/s up) while the actual network speed in bldg A was lower than it is now (close to those 200). I'm aware that the wireless connection between those buildings should slow things down, but I'm wondering why this difference has become that extreme. Thanks for any tips... Update: I currently want to upload a large file (1.5 GB) via FTP (FileZilla). Since that caused the D-Link to disconnect (as described in first post), I took my laptop to bldg A, connected directly to the original WLAN (bypassing my D-Link) and tried the same upload. Guess what - same issue: At some point the connection is dead (at this point I would have reset my D-Link if I was connected to it). Just as the D-Link, my laptop is still connected, but not even name resolution is working ("Looking for..." in Firefox). After reconnecting, it's working again. Maybe my D-Link isn't the problem at all...

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• How to tune system settings for mongoDB on Linux?

  - by jsh

  Trying to squeeze a lot out of one question here -- please bear with me. Although the MongoDB man pages make several useful recommendations about system settings like ulimit (http://docs.mongodb.org/manual/reference/ulimit/), and other production factors (http://docs.mongodb.org/manual/administration/production-notes/) they seem mysteriously silent on things like virtual memory and swap settings. The closest we get to a hint is that "...the operating system’s virtual memory subsystem manages MongoDB’s memory..." (http://docs.mongodb.org/manual/faq/fundamentals/#does-mongodb-require-a-lot-of-ram). Running the same job - high writes and high reads on about 10,000,000 records in a single collection -- on my 4-processor, 4GB RAM macbook and an 8-core ubuntu box with 64GB RAM I saw dramatically WORSE read performance on the linux box with factory settings, and could hear the disk constantly spinning, indicating high I/O and presumably swapping. Yes, other things were happening on the box, but there was plenty of free RAM, disk space, etc.; furthermore, I did not see evidence that Mongo was expanding to take advantage of all that free RAM as it is touted to do. Linux box default settings were as follows: vm.swappiness =60 vm.dirty_background_ratio = 10 vm.dirty_ratio = 20 vm.dirty_expire_centisecs =3000 vm.dirty_writeback_centisecs=500 I hazarded some guesses looking at docs and blogs for other types of databases (Oracle, MYSQL, etc.), experimented, and adjusted as below. vm.swappiness=10 vm.dirty_background_ratio=5 vm.dirty_ratio=5 vm.dirty_writeback_centisecs=250 vm.dirty_expire_centisecs=500 I saw some immediate apparent improvements in read time. However, when I ran my test jobs again, read performance continued to be painfully sluggish during heavy writes. Then, I REBUILT the collection from an available data source - and suddenly I can read at 1ms or less per record WHILE doing the write job! So the question is really two-fold: 1) What are appropriate VM settings for MongoDB on Linux? 2) (bonus) Does Mongo do some checking or optimization with the OS while data is being built? In other words, if I have built a large data set with suboptimal VM or I/O settings, does Mongo make assumptions during the memory-mapping process that will fail to take advantage of optimizations down the road? Obviously I don't fully grok memory mapping under the hood (I was hoping I wouldn't have to). Any help appreciated...thanks! -j

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• What happens to missed writes after a zpool clear?

  - by Kevin

  I am trying to understand ZFS' behaviour under a specific condition, but the documentation is not very explicit about this so I'm left guessing. Suppose we have a zpool with redundancy. Take the following sequence of events: A problem arises in the connection between device D and the server. This causes a large number of failures and ZFS therefore faults the device, putting the pool in degraded state. While the pool is in degraded state, the pool is mutated (data is written and/or changed.) The connectivity issue is physically repaired such that device D is reliable again. Knowing that most data on D is valid, and not wanting to stress the pool with a resilver needlessly, the admin instead runs zpool clear pool D. This is indicated by Oracle's documentation as the appropriate action where the fault was due to a transient problem that has been corrected. I've read that zpool clear only clears the error counter, and restores the device to online status. However, this is a bit troubling, because if that's all it does, it will leave the pool in an inconsistent state! This is because mutations in step 2 will not have been successfully written to D. Instead, D will reflect the state of the pool prior to the connectivity failure. This is of course not the normative state for a zpool and could lead to hard data loss upon failure of another device - however, the pool status will not reflect this issue! I would at least assume based on ZFS' robust integrity mechanisms that an attempt to read the mutated data from D would catch the mistakes and repair them. However, this raises two problems: Reads are not guaranteed to hit all mutations unless a scrub is done; and Once ZFS does hit the mutated data, it (I'm guessing) might fault the drive again because it would appear to ZFS to be corrupting data, since it doesn't remember the previous write failures. Theoretically, ZFS could circumvent this problem by keeping track of mutations that occur during a degraded state, and writing them back to D when it's cleared. For some reason I suspect that's not what happens, though. I'm hoping someone with intimate knowledge of ZFS can shed some light on this aspect.

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