Server :: Software Raid 5 Write Performance
Nov 16, 2010
I wasn't sure where to post this question so administrators, feel free to move it.I have a media server I set up running Ubuntu 10.4 Server, and I set up a software raid 5 using 5 Western Digital Caviar Green 2TB 7200RPM 64MB drives. Individually they benchmark (using the Ubuntu's mdadm GUI (pali?somthing...) at about 100-120mb/s read write.I set the raid 5 up with a stripe size of 256kb, and then I waited the 20 hours it took to synchronize. My read speeds in raid are up to 480mb/s, but my write max is just under 60mb/s. I knew my write performance would be quite a bit lower than my read, but I was also expecting at least single drive performance. I have seen other people online with better results in software, but have been unable to achieve the results they have gotten.
My bonnie++ results are more or less identical (I used mkfs.ext4 and set the stride and stripe-width).The PC has 2048mb of RAM and a 2.93Ghz Dual Core Pentium (Core 2 Architecture), so I doubt think that's the bottle neck. These drives are on the P55 (P45*) South Bridge SATA controller.
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Jan 5, 2011
I have recently migrated my file server over to a HP Microserver. The server has two 1TB disks, in a software RAID-1 array, using MDADM. When I migrated simply moved the mirrored disks over, from the old server Ubuntu 9.10 (server) to the new one 10.04.1 (server).I Have recently noticed that write speed to the RAID array is *VERY* slow. In the order of 1-2MB/s order of magnitude (more info below). Now obviously this is not optimal performance to say the least. I have checked a few things, CPU utilisation is not abnormal (<5%) nor is memory / swap. When I took a disk out and rebuilt the array, with only one disk (tried both) performance was as to be expected (write speed >~70MB/s) The read speed seems to be unaffected however!
I'm tempted to think that there is something funny going on with the storage subsystem, as copying from the single disk to the array is slower than creating a file from /dev/zero to the array using DD..Either way I can't try the array in another computer right now, so I though I was ask to see if people have seen anything like this!At the moment I'm not sure if it is something strange to do with having simply chucked the mirrored array into the new server, perhaps a different version of MDADM? I'm wondering if it's worth backing up and starting from scratch! Anyhow this has really got me scratching my head, and its a bit of a pain! Any help here would be awesome, e-cookies at the ready! Cheers
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Sep 7, 2010
I'm currently experiencing some serious issues with WRITE performance on a RAID-1 array. I'm running Ubuntu 10.04 64 bit server with the latest updates. To evaluate the performance ran the following test: [URL]... (great article btw!) Using dd to measure, write performance is only at 8.7 MB/s. Read is great though at 74.5 MB/s. The tests were ran straight after rebooting and I have not (YET!) done any kernel tuning or customization, running the default server package of the Ubuntu kernel. Here's the motherboard in the server: [URL]... with a beta bios to support drives over 300GB.
[code]...
As you can see from the bo column there is definitely something stalling. As per top output, the %wa (waiting for i/o) is always around %75 however as per above, writes are stalling. CPU is basically idle all the time. Hard drives are quite new and smartctl (smartmontools) does not detect any faults.
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Oct 27, 2010
So I have been doing some RAID 5 performance testing and am getting some bad write performance when configuring the RAID with an even number of drives. I'm running kernel 2.6.30 with software based RAID 5. This seems rather odd and doesn't make much since to me. For RAID 0 my performance consistently increases as I add more drives, but this is not the case for RAID 5. Does anyone know why I might be seeing lower performance when constructing my RAID 5 with 4 or 6 drives rather than 3 or 5?
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May 20, 2010
Compared to my laptop notebook with a HD of 5400rpm, the write performance of raid1 on an ubuntu lucid server is unacceptable. In the begining, I installed ubuntu 9.04 server(alternate) using raid1 with two WD 1TB HDs of 7200rpm(Green Power) and then performed dist upgrade to 9.10 and then to 10.04.
I guess the write performance initially was reasonable since the installation and data migration(copy from another computer over LAN) didn't take too much time. However, after upgrading the server to 9.10 or so, I found large file upload through samba or ftp tends to block and time out. It is of no use whether to change the daemon or the client program so that I tried to test the read/write performance on the server to figure out the situation.
To my surprise, using strace I found even a simple program like cp would easily get blocked eventually in a write() system call for decades of seconds. Hence, I perform another disk writing test using dd for data size ranging from 50MB to 1GB. Performance test commands are listed as follows:
Quote: dd if=/dev/zero of=test.img count=[5|10|15|20|100] bs=10M
if the data to write is equal or fewer than 150MB, the command returns immediately at very hight speed but the raid disks starts to sync and busy so that the terminal prompt seems to freeze. I think this behavior is normal under the raid1 configuration, isn't it?
But when the data size is equal to 200MB, the test command blocks for seconds and the write speed is measured at about 16.6MB/s. Of course, the raid disk still starts to sync and busy afterwards. Next, I test writing with data of size 1GB. The command blocks so long for about 770 seconds(<2MB/s) while the same test runs for only 17.49 seconds(60MB/s) on my laptop.
I also burn a Lucid LiveCD to boot the server and mount the raid device to run the test again but the results remain similar. Does that means even I re-install the system on the raid, the problem never disappears?
PS: the disks run under the mode of UDMA6 without change.
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Jun 23, 2011
I'm looking to set up a server with attached mass storage device and tape autoloader to run linux. It's set up under Windows at the moment. Goal is to have users, connecting from individual workstations and laptops, backup their data to the linux server. On their personal machine, some users run linux, some MacOS, some Windows. I plan to set up the 5 500 GB drives as RAID5. I understand that if setting up as software raid the format is "physical volume for RAID". Under this setup, will Windows users be able to read/write and function as expected? I can't assume only linux user access.
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Jul 16, 2011
I built a RAID5 storage array using 'mdadm' on 3x WD Green 1TB hard drives. I used the Disk Utility GUI to create the array and it took about 24 hours to build. When I started copying files to it I noticed it performed at decent speeds for a while, then got really slow, the sped back up. Just for laughs I ran the Read-Only Benchmark function in the Disk Utility and got a graph that would even confuse stock brokers.Any thought on what the issue might be? I tried searching around for an answer, but most people are only affected by wirte performance issues not reading.
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Sep 12, 2010
I've been having some problems copying files to USBs. If I'm copying a large (100MB+) amount of data, at random points the transfer will just stop for 30+ seconds before continuing. Sometimes it doesn't start up again at all. Consequently, the write speed drops to less than 1MB/sec, sometimes as low as 100 KB/sec. I do not have these problems on Windows 7, where I achieve speeds of ~16 MB/sec easily. I have had the same results with several USBs (2-32 GB) on several file systems (fat32, ext2) with several different computers running fully patched versions of Ubuntu 10.04, which suggests the problem is related to the way the OS accesses the hardware.
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Oct 27, 2010
I am experiencing disk write performance issues and I cannot find the cause. I have LSI-9211-8i SAS 2 controller (latest firmware), Centos 5.5 latest x86_64 kernel (2.6.18-194.17.4.el5 #1 SMP with latest LSI driver v. 7.00 datet Jul 27) and Seagate Cheetah ST3600057SS drives. These drives have a std write performance (sustained) of > 200MB/s (and read as well); with Fedora core 13 (same machine), issuing a dd if=/dev/zero of=/dev/sdo bs=1024k count=16384 (16 GB direct device write), gets normally to 213 MB/s (repeated retries). On Centos 5.5 I am getting speeds around 110/113 MB/s.
iostat does not show anything specific (just 1.3 % wait, CPU 99.7 idle).
There are 14 drives: tried with several of them, same figures. Reads go around 200 MB/s.
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Jun 30, 2011
I installed on a Intel SR2612UR Server with integrated LSI Expander and a Adaptec 5805Z controller a Raid 6 Array with 12x 2TB Drives (2 ext4 Partition: 16TB, 2TB), but I get very poor read speed depending on the blocksize that I set it vary between 130 MB/s and maximally 170 MB/s which is really poor for a Raid 6 Array of 12 drives, on a similar Dell Server I get above 650 MB/s. The Adaptec Controller has the latest Firmware installed.
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Mar 17, 2010
I just did a fresh install of Fedora 11 and added Raid 1 following this tutorial:[URL].. Now I see the filesystem when I open 'Computer' in the GUI, and I open it and see 'lost+found', but i can't write to the drive. The option is simply greyed out. And when I view Properties on the drive and go to Permissions, it says 'The permissions of {driveid} could not be determined.'
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Mar 17, 2010
I just did a fresh install of Fedora 11 and added Raid 1 following this tutorial: [URL]
Now I see the filesystem when I open 'Computer' in the GUI, and I open it and see 'lost+found', but i can't write to the drive. The option is simply greyed out. And when I view Properties on the drive and go to Permissions, it says 'The permissions of {driveid} could not be determined.'
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Sep 2, 2009
I am trying to prepare my PowerEdge 2950 before CentOS 5.3 installation(web server). I have hardware RAID 1/10 so I will have 2 virtual disks(VD).
First VDRAID 1) - 2 physical disks
Second VDRAID 10) - 4 physical disks
What should be write policy for the VD(RAID 1) and for the VD(RAID 10)? I would have "/var" and maybe "/tmp" on RAID 10.
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Aug 9, 2011
I have recently installed Debian on my NAS server. I have also configured Samba for sharing the home directory of a nas user i.e. /home/nas To this directory I have read/write from a windows machine using the nas user credentials. When I mount my RAID partition /dev/md0p1 to the /home/nas directory, I then realize that all content in this directory (files and subfolders) is only owned by the root user. When trying to access from the windows machine the /home/nas directory, I do not have any write access, only read. I have tried both the nas and the root user credentials.
I have also attempted the change the ownership of the mounted RAID partition to the nas user with the -R recursive option, but I get for the internal files/subfolders an error "operation not supported".
How can I overcome this problem? - Is there something not done properly in the /dev/md0 array definition (i.e. ARRAY /dev/md0 level=raid1 num-devices=2 UUID=bddf8b69:c97967b5:cb104784:7fef7cc3 )?- Is there something not done properly in the /dev/md0p1 mounting (i.e. mount /dev/md0p1 /home/nas)?- Should I do any extra configuration before the mounting etc? I would really appreciate any kind of help I could get.
Some background info
b) After OS boot, when I do a:
# cat /proc/mdstat,
I get:
Personalities : [raid1]
md0 : active (auto-read-only) raid1 sda1[0] sdb1[1]
4200896 blocks
unused devices: <none>
[Code]...
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Mar 19, 2010
I just did a fresh install of Fedora 11 and added Raid 1 for two additional drives during the install,
So, I have 3 drives. One with the OS, that I boot from. /dev/sdc
Then 2 others in a Raid 1 config, /dev/sda and /dev/sdb -- those are in /dev/md0
Everything with the system is fine. I can boot up, and everything runs great. So then I try to view the Raid and it looks ok when I open 'Computer'. it shows the main OS drive, and what looks like the 2000GB raid drive. So i open it and just see a 'lost+found' folder. Not surprising, b/c I haven't added anything to it. But when I right-click I can't create a folder b/c it's greyed out, I can't drop files in there, and when I get Properties on the drive itself it says 'The permissions of {driveid} could not be determined.'
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Mar 22, 2011
How long does hardware Raid card (raid 1, 2 drives)take to mirror a 1 TB drive (500gb used)?Is there a general rule of thumb for this?4 hours? 12 hours? 24 hours?
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Aug 3, 2010
I am trying to connect a RAID Box to the server via LSI 8880EM2 RAID controller.The raid box is FUjitsu Externus DX60 with raid 1 configured.The server is Fujitsu Primergy SX300 S5 with LSI 8880EM2 RAID card.The external raid box is being recognised by the raid controllers bios.
The server runs CentOS 5.5 64bit. I have installed the megaraid_sas driver from LSI website and MegaCLI utility but CentOS still fails to see the box.MegaCLI utility, when launched from CentOS, recognises the raid box, CentOS does not(no mapping being created in /dev).
I have also tried to create a logical RAID0 HDD on one physical HDD(as seen by MegaCLI) with MegaCLI utility in CentOS.The result was success and the new logical drive could have been used, but when restarting the server, the controllers' bios fails with an error (not surprised(one logical RAID0 on one physical HDD)) and configuration is being erased.
Has anyone tried connecting 8880EM2 controller to a raid box with raid configured on the box, running it all under CentOS and what were the results.
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Mar 3, 2010
I have a 4 drive RAID 5 array set up using mdadm. The system is stored on a seperate physical disk outside of the array. When reading from the array its fast but when writing to the array its extremely slow, down to 20MB/Sec compared to 125MB/Sec reading. It does a bit then pauses, then writes a bit more and then pauses again and so on.The test i did was to copy a 5GB file from the RAID to another spare non-raid disk on the system average speed 126MB/s. Copying it back on to the RAID (in another folder) the speed was 20MB/s.The other thing is very slow several KB/s write speed copying from eSATA drive to the RAID.
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Jul 2, 2010
Can anyone tell me in performance tunning of apache-tomcat and jboss application server?when I deploy some application in apache-tomcat the performance is say 100 users per second and incase of jboss it is even worst (35-40 users per second)i want to improve my performance 1000 uesrs per second..
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Feb 25, 2009
I have a weird performance issue with a centos 5 running a nfs server and a rh8 client. I think the fact that it is rh8 client should be downplayed. It is just that with rh8 client the performance degradation seems more clear. See test details below OS in server is Centos 5 x86_64 kernel 2.6.18-92.1.22.el5
1Gb connection between machines File to test over NFS is a 1GB file. First of all I wanted to measure how the network alone performs while using NFS. So in the server side I run a "cat" command on the 1GB file to /dev/null. Please note that the disk read speed is about 98MBs. At this point the file system has the 1GB file cached in memory. In the client side a "cat" on the same file gives me a speed of about 113MBs. It seems then that the bottleneck in this instance is the network and it is very close to nominal speed. So the network performance is really good. (BTW I know that the server got that file from cache because a vmstat or iostat shows no disk activity.)
The second test is reading from disk with no caching involve. In the server I flushed the 1GB file from the memory. For instance by reading another 5GB file and I repeat the same thing as above in the client (a cat on the 1GB file). Now, the server has to go to disk.(vmstat or iostat shows the disk activity). However the performance, now, is about 20MBs, I was expecting something closer so 90MBs. (since the reading speed in the server in the first test showed 98MBs).
This second test was repeated for ext2, ext3, xfs with no significant differences. A similar test using a RH8 NFS server and client gets me close to 60MBs for a 1GB file not cache by the file system in the serverSince network speeds and disk read speeds are not the bottlenecks ... what or where is the limiting factor then?
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Jul 21, 2011
I am looking to convert a raid 1 server I have to raid 10. It is using software raid, currently I have 3 drives in raid 1. Is it possible to boot into centos rescue, stop the raid 1 array. Then create the raid 10 with 4 drives, 3 of which still has the raid 1 metadata, will mdadm be able to figure it out and resync properly keeping my data? or is there a better way to do it?
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Mar 24, 2011
I have a box that doesn't have a Raid controller or a software raid running currently. I would like to make it a RAID 1. Since it seems there isn't any IDE RAID controllers hardly around, I have another HD that is the exact model as the drive currently in the box running CentOS. Can I some how add the second drive and get the box to mirror from here own out? The box gets really hot and I want to be ready for a HD failure.
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Feb 4, 2010
On my local apache web server I had installed gnome desktop, because I wanted it to use as a TV. But when I installed the gnome desktop, my requests for web pages became terribly slow (4-5 seconds!). When I deinstalled the gnome desktop, the request where fast again. But I still want to watch TV on my server, so I wander if people know why the gnome desktop harms the performance of the server?
PS. with gnome desktop, ping was <1 ms, samba server worked like charm, wget localhost was <1 ms, but for some reason, when tried to get a webpage from my webserver to a remote machine, it took seriously 4-5 seconds to load a page.
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Jul 31, 2010
I just wanted to know if having my laptop set to ondemand, will this affect performance in any way? I realize it increases the clock speed to performance when the CPU is under load, but does the time it take to go from ondemand to performance affect speed? Will there be any noticeable difference between the two setups? I have a dual core intel at 2.2GHz when in performance. When ondemand is set with no load it downclocks to 800Mhz.
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Feb 1, 2011
Could any RAID gurus kindly assist me on the following RAID-5 issue?I have an mdadm-created RAID5 array consisting of 4 discs. One of the discs was dropping out, so I decided to replace it. Somehow, this went terribly wrong and I succeeded in marking two of the drives as faulty, and the re-adding them as spare.
Now the array is (logically) no longer able to start:
mdadm: Not enough devices to start the array.Degraded and can't create RAID ,auto stop RAID [md1]
I was able to examine the disks though:
Code:
root@127.0.0.1:/etc# mdadm --examine /dev/sdb2
/dev/sdb2:
Magic : a92b4efc
Version : 00.90.00
code....
Code:
mdadm --create --assume-clean --level=5 --raid-devices=4 /dev/sda2 /dev/sdb2 /dev/sdc2 /dev/sdd2
As I don't want to ruin the maybe small chance I have left to rescue my data, I would like to hear the input of this wise community.
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Oct 2, 2010
I am hosting apache service on the CentOS5.4. I configure the Apache in default setting mostly. But keep getting complaints from others about the website download too slow, pdf cannot download at all, flash cannot play smoothly, etc.. But on my own machine, everything works fine. Is there any tool for analyzing this problem?
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Jan 29, 2010
how much of a performance impact full disk encryption (say, AES 256-bit) has on disk-related activities? On one particular project I'm involved in I am trying to weigh out security vs performance issues.
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Jan 4, 2011
I have installed a linux server, centos gui server with Raid1, his role will be only a file server. I installed samba and configured it. The file system is EXT3. the server got 4 gigs of memory.There is a program in windows that writes files to the share.I searched and i found that there is some commands that you add and they boost the performance.
I got complains that the writes are not fast enough. Before me another IT guy configured the file server and it was faster, what he told my customer that he changed some command of cache but i dont know exactly what he did. I have been asked to find how to boost the performance.Please give me more commands to try to boost the performance of Samba or tell me if i need to change anything..
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Jun 22, 2010
Just want to know if solid state drive supported by slackware 13.1? Coz I want it to try to boost my server performance???
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Feb 7, 2011
I'm trying to setup RAID 1 on a CentOS 5 server for a zimbra email server.I get a partion schema error. Can I do this?The server is a HP Proliant ML150 G3 server with two 80GB HDD.
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