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  • Strange performance issue with Dell R7610 and LSI 2208 RAID controller

    - by GregC
    Connecting controller to any of the three PCIe x16 slots yield choppy read performance around 750 MB/sec Lowly PCIe x4 slot yields steady 1.2 GB/sec read Given same files, same Windows Server 2008 R2 OS, same RAID6 24-disk Seagate ES.2 3TB array on LSI 9286-8e, same Dell R7610 Precision Workstation with A03 BIOS, same W5000 graphics card (no other cards), same settings etc. I see super-low CPU utilization in both cases. SiSoft Sandra reports x8 at 5GT/sec in x16 slot, and x4 at 5GT/sec in x4 slot, as expected. I'd like to be able to rely on the sheer speed of x16 slots. What gives? What can I try? Any ideas? Please assist Cross-posted from http://en.community.dell.com/support-forums/desktop/f/3514/t/19526990.aspx Follow-up information We did some more performance testing with reading from 8 SSDs, connected directly (without an expander chip). This means that both SAS cables were utilized. We saw nearly double performance, but it varied from run to run: {2.0, 1.8, 1.6, and 1.4 GB/sec were observed, then performance jumped back up to 2.0}. The SSD RAID0 tests were conducted in a x16 PCIe slot, all other variables kept the same. It seems to me that we were getting double the performance of HDD-based RAID6 array. Just for reference: maximum possible read burst speed over single channel of SAS 6Gb/sec is 570 MB/sec due to 8b/10b encoding and protocol limitations (SAS cable provides four such channels).

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  • Looking for application performance tracking software

    - by JavaRocky
    I have multiple java-based applications which produce statistics on how long method calls take. Right now the information is being written into a log file and I analyse performance that way. However with multiple apps and more monitoring requirements this is being becoming a bit overwhelming. I am looking for an application which will collect stats and graph them so I can analyse performance and be aware of performance degradation. I have looked at Solarwinds Application Performance Monitoring, however this polls periodically to gather information. My applications are totally event based and we would like to graph and track this accordingly. I almost started hacking together some scripts to produce Google Charts but surely there are applications which do this already. Suggestions?

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  • Hyper-V performance comparisons vs physical client?

    - by rwmnau
    Are there any comparisons between Hyper-V client machines and their physical equivalent? I've looked around and can find 4000 articles about improving Hyper-V performance, but I can't find any that actually do a side-by-side comparison or give benchmarking numbers. Ideally, I'm interested in a comparison of CPU, memory, disk, and graphics performance between something like the following: Some powerful workstation (with plenty of RAM) with Windows 7 installed on it directly Same exact worksation with Hyper-V Server 2008 R2 (the bare Server role) and a full-screen Windows 7 client machine Virtual Server 2005 had performance that didn't compare at all with actual hardware, but with the advances in CPU and hardware-level virtualization, has performance improved significantly? How obvious would it be to a user of the two above scenarios that one of them was virtualized, and does anybody know of actual benchmarking of this type?

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  • LTO 2 tape performance in LTO 3 drive

    - by hmallett
    I have a pile of LTO 2 tapes, and both an LTO 2 drive (HP Ultrium 460e), and an autoloader with an LTO 3 drive in (Tandberg T24 autoloader, with a HP drive). Performance of the LTO 2 tapes in the LTO 2 drive is adequate and consistent. HP L&TT tells me that the tapes can be read and written at 64 MB/s, which seems in line with the performance specifications of the drive. When I perform a backup (over the network) using Symantec Backup Exec, I get about 1700 MB/min backup and verify speeds, which is slower, but still adequate. Performance of the LTO 2 tapes in the LTO 3 drive in the autoloader is a different story. HP L&TT tells me that the tapes can be read at 82 MB/s and written at 49 MB/s, which seems unusual at the write speed drop, but not the end of the world. When I perform a backup (over the network) using Symantec Backup Exec though, I get about 331 MB/min backup speed and 205 MB/min verify speeds, which is not only much slower, but also much slower for reads than for writes. Notes: The comparison testing was done on the same server, SCSI card and SCSI cable, with the same backup data set and the same tape each time. The tape and drives are error-free (according to HP L&TT and Backup Exec). The SCSI card is a U160 card, which is not normally recommended for LTO 3, but we're not writing to LTO 3 tapes at LTO 3 speeds, and a U320 SCSI card is not available to me at the moment. As I'm scratching my head to determine the reason for the performance drop, my first question is: While LTO drives can write to the previous generation LTO tapes, does doing so normally incur a performance penalty?

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  • Store Varnish cache in hard disk

    - by Great Kuma
    Hello, The situation is: Im building PHP application, and need http caching. Varnish is great, and lots of people tell me that Varnish store the cached data in RAM. But I want it cached in hard disk. Is there any way to store the Varnish cached data in hard disk? thanks.

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  • Raid-5 Performance per spindle scaling

    - by Bill N.
    So I am stuck in a corner, I have a storage project that is limited to 24 spindles, and requires heavy random Write (the corresponding read side is purely sequential). Needs every bit of space on my Drives, ~13TB total in a n-1 raid-5, and has to go fast, over 2GB/s sort of fast. The obvious answer is to use a Stripe/Concat (Raid-0/1), or better yet a raid-10 in place of the raid-5, but that is disallowed for reasons beyond my control. So I am here asking for help in getting a sub optimal configuration to be as good as it can be. The array built on direct attached SAS-2 10K rpm drives, backed by a ARECA 18xx series controller with 4GB of cache. 64k array stripes and an 4K stripe aligned XFS File system, with 24 Allocation groups (to avoid some of the penalty for being raid 5). The heart of my question is this: In the same setup with 6 spindles/AG's I see a near disk limited performance on the write, ~100MB/s per spindle, at 12 spindles I see that drop to ~80MB/s and at 24 ~60MB/s. I would expect that with a distributed parity and matched AG's, the performance should scale with the # of spindles, or be worse at small spindle counts, but this array is doing the opposite. What am I missing ? Should Raid-5 performance scale with # of spindles ? Many thanks for your answers and any ideas, input, or guidance. --Bill Edit: Improving RAID performance The other relevant thread I was able to find, discusses some of the same issues in the answers, though it still leaves me with out an answer on the performance scaling.

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  • Using SSD as disk cache

    - by casualcoder
    Is there software for Linux to use an SSD as disk cache? I believe that Sun does something like this with ZFS, though not sure. A quick search provides nothing suitable. The goal would be to put frequently requested files on the SSD on-the-fly. Since the SSD has more capacity than RAM for less money and better performance than hard disk, this should provide an efficient performance boost.

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  • How to measure disk-performance under Windows?

    - by Alphager
    I'm trying to find out why my application is very slow on a certain machine (runs fine everywhere else). I think i have traced the performance-problems to hard-disk reads and writes and i think it's simply the very slow disk. What tool could i use to measure hd read and write performance under Windows 2003 in a non-destructive way (the partitions on the drives have to remain intact)?

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  • Good C++ books regarding Performance?

    - by Leon
    Besides the books everyone knows about, like Meyer's 3 Effective C++/STL books, are there any other really good C++ books specifically aimed towards performance code? Maybe this is for gaming, telecommunications, finance/high frequency etc? When I say performance I mean things where a normal C++ book wouldnt bother advising because the gain in performance isn't worthwhile for 95% of C++ developers. Maybe suggestions like avoiding virtual pointers, going into great depth about inlining etc? A book going into great depth on C++ memory allocation or multithreading performance would obviously be very useful.

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  • How to clear Windows disk read cache?

    - by Sebastiaan Megens
    For performance testing I need to clear Windows' disk read cache. I tried googling but I couldn't find anything other than rebooting or other manual stuff. Before I give in and do that, I'd like to know if anyone knows of a way to clear Windows disk read cache. I'm testing on Windows 7, but I'm also interested in Windows XP solutions.

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  • Bad performance with Linux software RAID5 and LUKS encryption

    - by Philipp Wendler
    I have set up a Linux software RAID5 on three hard drives and want to encrypt it with cryptsetup/LUKS. My tests showed that the encryption leads to a massive performance decrease that I cannot explain. The RAID5 is able to write 187 MB/s [1] without encryption. With encryption on top of it, write speed is down to about 40 MB/s. The RAID has a chunk size of 512K and a write intent bitmap. I used -c aes-xts-plain -s 512 --align-payload=2048 as the parameters for cryptsetup luksFormat, so the payload should be aligned to 2048 blocks of 512 bytes (i.e., 1MB). cryptsetup luksDump shows a payload offset of 4096. So I think the alignment is correct and fits to the RAID chunk size. The CPU is not the bottleneck, as it has hardware support for AES (aesni_intel). If I write on another drive (an SSD with LVM) that is also encrypted, I do have a write speed of 150 MB/s. top shows that the CPU usage is indeed very low, only the RAID5 xor takes 14%. I also tried putting a filesystem (ext4) directly on the unencrypted RAID so see if the layering is problem. The filesystem decreases the performance a little bit as expected, but by far not that much (write speed varying, but 100 MB/s). Summary: Disks + RAID5: good Disks + RAID5 + ext4: good Disks + RAID5 + encryption: bad SSD + encryption + LVM + ext4: good The read performance is not affected by the encryption, it is 207 MB/s without and 205 MB/s with encryption (also showing that CPU power is not the problem). What can I do to improve the write performance of the encrypted RAID? [1] All speed measurements were done with several runs of dd if=/dev/zero of=DEV bs=100M count=100 (i.e., writing 10G in blocks of 100M). Edit: If this helps: I'm using Ubuntu 11.04 64bit with Linux 2.6.38. Edit2: The performance stays approximately the same if I pass a block size of 4KB, 1MB or 10MB to dd.

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  • Why is the disk making my motherboard beep?

    - by Mark Ransom
    Whenever I let my PC do heavy disk accesses for a long time, the speaker on the motherboard starts making a continuous chirping sound. Thankfully it doesn't happen often, but it drives me nuts when it does. Anybody know where this sound might be coming from, or have any hints as to how to track it down? Edit: The problem appears to be with the processor, the correlation with disk access was coincidental. Thanks for all the answers.

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  • How do I Change a damaged Disk in a Raid 5 array

    - by Egakagoc2xI
    Hi, I have a server with a 4-drives Raid 5 array; one of the disks is damaged. All the disks are hot pluggable. My Question is, I want to replace the damaged disk with a new one, do I have to shutdown the server or should I just change the hard disk with the server on and it will rebuild the array? There is a procedure to follow? My Server is a HP. Regards.

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  • Windows 7 keeps insisting that it needs to check disk for consistency, but never does

    - by Mike
    Lately Windows 7 has been telling me that I need to check disk D: for consistency. This happens more than 50% of the time when booting up. The first time, I didn't touch anything so that it would go ahead and do its scan. It didn't seem to do anything - just booted straight into Windows. The second time I tried to skip it by pressing any key. It ignored all of my keystrokes and still counted down to 0 (then skipped the disk check). Sometimes, it gets down to 0 but then just hangs... no indication that anything is going on. This is happening on a < 3 month old laptop. C: and D: are on the same physical disk - just two partitions. I never get any notification that C: needs to be checked for consistency. It's a ~300GB HD. C: has 60gb (32gb free) and D: has ~240GB (122gb free). What could be causing this to keep coming up? What can I do to fix it? Thanks!

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  • After reinstallation, Disk Cleanup disappears when I click OK.

    - by James
    After I reinstalled Windows 7, Disk Cleanup stopped working. I can start Disk Cleanup and select the drive to clean, but when I click on the OK button, the window disappears. Any solutions? Here's the data from Windows LogsApplication :- EventData 1744235005 1 APPCRASH Not available 0 cleanmgr.exe 6.1.7600.16385 4a5bc5e1 Csi.dll 14.0.4733.1000 4b5662be c0000005 00135213 F:\Users\Jacob\AppData\Local\Temp\WER419.tmp.WERInternalMetadata.xml F:\Users\Jacob\AppData\Local\Microsoft\Windows\WER\ReportArchive\AppCrash_cleanmgr.exe_6514b6ecb633f97cbf78e3a5bcae2c4bd74351_0d3b109c 0 75fa9599-41b1-11e0-b864-001966b2bcb6 0 The above one was with an Information icon. The one below was with an Error icon:-- EventData cleanmgr.exe 6.1.7600.16385 4a5bc5e1 Csi.dll 14.0.4733.1000 4b5662be c0000005 00135213 bbc 01cbd5be36b572bf F:\Windows\system32\cleanmgr.exe F:\Program Files\Common Files\Microsoft Shared\OFFICE14\Csi.dll 75fa9599-41b1-11e0-b864-001966b2bcb6 I also used process explorer:- When i started disk cleanup, a cleanmgr.exe process appeared under explorer.exe.But when i clicked on the "OK" button after selecting the drive, cleanmgr.exe was there for some seconds before it disappeared. But a new process - WerFault.exe appeared under svchost.exe a few seconds after i clicked the "OK" button. It disappeared, too, from the process list after some time (i think it disappeared along with cleanmgr.exe).

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  • Win 2008 R2 - copying TO disk is very slow, copying FROM is more or less okay

    - by avs099
    I have Windows 2008 R2 SP1 with 4 identical SATA disks (Seagate Barracude 7200) in RAID 5 array. It has 4Gb of memory; all recent updates are installed. Problem: when I copy large file from one folder to another, I get about 10MB/s average speed. When I read this file from network share via 1Gbps connection - I get about 25-30 MB/s. Both numbers seems to be low for me - but specifically I'm very frustrated with low write speed. there is no antivirus, no hyper-v, it's just a fileserver - i when i do my tests nobody else reads/write from it (we have only 4 people in a team, so I'm sure). Not sure if that matters, but there is only 1 logic disk "C" with all available space (1400 GB). I'm not an admin at all, so I have no idea where to look and what other information to provide. I did run performance monitor with "% idle time", "avg bytes read", "avg byte write" - here is the screenshot: I'm not sure why there are such obvious spikes. Any idea? Please let me know if you need me to provide more information - what counters should I check, etc. I'm very eager to get this solved. Thank you. UPDATE: we have another Windows 2008 R2 SP1 server with 2 RAID1 arrays - one is disk C (where windows is installed, another one is disk E). It is running Hyper-V and does not have antivirus. I noticed the following behavior when I copy large file (few GBs): C - C: about 50MB/sec C - E: about 55MB/sec E - E: 8MB/sec!!! E - C: 8MB/sec!!! what could cause this?? E drive is RAID1 array from same Seagate Barracuda 1TB drives..

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  • High disk I/O - jbd2/sda2-8 process

    - by Evan Hamlet
    I have run a file server on a CentOS 5.8 final server. My only concern at the moment is what appears to be intermittent but continuous high disk I/O activity causing a general slowdown because of jbd2/sda2-8 process. jbd2/sda2-8 is making use of /dev/sda2, which is the 2nd partition of the first harddrive (IE: root partition). More info: using "iotop" the culprit appears to be "jbd2/sda1-8" making writes every second, which appears to be a kernel process associated with journaling on the ext4 filesystem, if my googling around is correct. I see "jbd2/sda2-8" appearing here every now and then, but certainly not every 3 seconds.. when idle, it appears about 1 or 2 times per minute. When I'm using the system, it appears more frequently. ATOP results: http://grabilla.com/02b14-8022db2e-4eb9-4f10-8e10-d65c49ad7530.png IOTOP results: http://grabilla.com/02b14-cf74b25d-4063-4447-9210-7d1b9b70e25b.png HTOP results: grabilla. com/02b14-ad8cad0e-89b0-46d3-849d-4fd515c1e690.png jbd2/sda2-8 is the processes I see with iotop making writes on disk even though it's not in use at all. Does someone has any idea how could I solve the high disk usage caused jbd2/sda2-8 process?

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  • Mac OS X Disk Encryption - Automation

    - by jfm429
    I want to setup a Mac Mini server with an external drive that is encrypted. In Finder, I can use the full-disk encryption option. However, for multiple users, this could become tricky. What I want to do is encrypt the external volume, then set things up so that when the machine boots, the disk is unlocked so that all users can access it. Of course permissions need to be maintained, but that goes without saying. What I'm thinking of doing is setting up a root-level launchd script that runs once on boot and unlocks the disk. The encryption keys would probably be stored in root's keychain. So here's my list of concerns: If I store the encryption keys in the system keychain, then the file in /private/var/db/SystemKey could be used to unlock the keychain if an attacker ever gained physical access to the server. this is bad. If I store the encryption keys in my user keychain, I have to manually run the command with my password. This is undesirable. If I run a launchd script with my user credentials, it will run under my user account but won't have access to the keychain, defeating the purpose. If root has a keychain (does it?) then how would it be decrypted? Would it remain locked until the password was entered (like the user keychain) or would it have the same problem as the system keychain, with keys stored on the drive and accessible with physical access? Assuming all of the above works, I've found diskutil coreStorage unlockVolume which seems to be the appropriate command, but the details of where to store the encryption key is the biggest problem. If the system keychain is not secure enough, and user keychains require a password, what's the best option?

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  • Linux disk usage analyser that acts like symlinks are real files

    - by Rory
    I am using git-annex, an extension to the DVCS git, which is designed for handling large files. It makes heavy use of symlinks. The actual large files are moved to the .git/annex directory and the original files are symlinked to there. I am running out of disk space, and need to clear up, and see what's using all my space. Usually I'd use a disk usage tool like ncdu, Baobab or Filelight. However they treat the symlink as essentially empty, and only count the file that it is pointing to as using any space. Which means when I use git-annex, it shows no space used in the main directories and lots of space used in the .git/annex directory. This is not helpful. Is there any (graphical or ncurses) based disk usage programme for linux (apt-get installable would be easie that is capable (through options or not) of counting a symlink as using up the space that the original file uses up? Many have options for different behaviour for hard links, so makes sense that some should h (I know counting symlinks as using space has flaws, like counting the space space twice, broken symlinks, etc. But that's OK for my purposes)

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  • puzzled with java if else performance

    - by user1906966
    I am doing an investigation on a method's performance and finally identified the overhead was caused by the "else" portion of the if else statement. I have written a small program to illustrate the performance difference even when the else portion of the code never gets executed: public class TestIfPerf { public static void main( String[] args ) { boolean condition = true; long time = 0L; int value = 0; // warm up test for( int count=0; count<10000000; count++ ) { if ( condition ) { value = 1 + 2; } else { value = 1 + 3; } } // benchmark if condition only time = System.nanoTime(); for( int count=0; count<10000000; count++ ) { if ( condition ) { value = 1 + 2; } } time = System.nanoTime() - time; System.out.println( "1) performance " + time ); time = System.nanoTime(); // benchmark if else condition for( int count=0; count<10000000; count++ ) { if ( condition ) { value = 1 + 2; } else { value = 1 + 3; } } time = System.nanoTime() - time; System.out.println( "2) performance " + time ); } } and run the test program with java -classpath . -Dmx=800m -Dms=800m TestIfPerf. I performed this on both Mac and Linux Java with 1.6 latest build. Consistently the first benchmark, without the else is much faster than the second benchmark with the else section even though the code is structured such that the else portion is never executed because of the condition. I understand that to some, the difference might not be significant but the relative performance difference is large. I wonder if anyone has any insight to this (or maybe there is something I did incorrectly). Linux benchmark (in nano) performance 1215488 performance 2629531 Mac benchmark (in nano) performance 1667000 performance 4208000

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  • Performance Testing Versus Unit Testing

    - by Mystagogue
    I'm reading Osherove's "The Art of Unit Testing," and though I've not yet seen him say anything about performance testing, two thoughts still cross my mind: Performance tests generally can't be unit tests, because performance tests generally need to run for long periods of time. Performance tests generally can't be unit tests, because performance issues too often manifest at an integration or system level (or at least the logic of a single unit test needed to re-create the performance of the integration environment would be too involved to be a unit test). Particularly for the first reason stated above, I doubt it makes sense for performance tests to be handled by a unit testing framework (such as NUnit). My question is: do my findings / leanings correspond with the thoughts of the community?

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