| OpenVZ and Linux md software raid sync slow [message #38699] |
Sun, 17 January 2010 02:17  |
ccto
Messages: 61
Registered: October 2005
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Member |
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Hello all,
We have multiple OpenVZ server running with x86 and x64 OS.
We notice that when a server crashed, or somehow the Linux md raid requires re-sync.
RAID 10, 4 x 500GB HDD to form a 1TB storage.
Under a OpenVZ kernel (e.g. 2.6.18-164.2.1.el5.028stab066.10ent), it takes a long time (e.g. 30 hours) to sync (speed is around 8000KB/sec)
# cat /proc/mdstat
Personalities : [raid10]
md0 : active raid10 sde1[3] sdd1[2] sdc1[1] sdb1[0]
976767872 blocks 64K chunks 2 near-copies [4/4] [UUUU]
[==>..................] resync = 12.3% (120280320/976767872) finish=1717.1min speed=8311K/sec
unused devices: <none>
# mdadm --detail /dev/md0
/dev/md0:
Version : 0.90
Creation Time : Wed Jun 24 00:45:22 2009
Raid Level : raid10
Array Size : 976767872 (931.52 GiB 1000.21 GB)
Used Dev Size : 488383936 (465.76 GiB 500.11 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 0
Persistence : Superblock is persistent
Update Time : Sun Jan 17 10:18:40 2010
State : clean, resyncing
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0
Layout : near=2
Chunk Size : 64K
Rebuild Status : 12% complete
UUID : 30f591b0:103cd46e:8c413dd3:256197d0
Events : 0.8914
Number Major Minor RaidDevice State
0 8 17 0 active sync /dev/sdb1
1 8 33 1 active sync /dev/sdc1
2 8 49 2 active sync /dev/sdd1
3 8 65 3 active sync /dev/sde1
If we reboot the machine into a Linux standard kernel to restart the resync process , it takes around 2 hours (re-sync speed is around 100MB/sec).
It happens a few times already on both x86 or x64 Linux and OpenVZ kernel.
Also, the CT under the OpenVZ container is very idle, those CT's LAVERAGE is nearly 0.
For production machines, we need to let the CT online, so online resync, and wait for a long time.
Is there any parameter(s) that we can adjust? or like host I/O etc. Please help
Thank you very much for your kind attention.
Regards
George
[Updated on: Sun, 17 January 2010 02:22] Report message to a moderator |
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