[Centos] RAID 1 sync

[Morten Tørmoen]

On Thu, 3 Feb 2005, Nigel Kendrick wrote:

> Is my new 300GB RAID 1 array REALLY going to take 18936 minutes to
> sync!!???

Hi Nigel,

If SW-RAID (i.e. raidtools / mdadm) :-

You can tune kernel parameters to increase max/min speed values here:

# cat /proc/sys/dev/raid/speed_limit_max
10000
# cat /proc/sys/dev/raid/speed_limit_min
100

Set this to, say, power of 10 (or more):

# sysctl -w dev.raid.speed_limit_max=100000
# sysctl -w dev.raid.speed_limit_min=1000

Additionally tweak it further up with:

# renice -20 `pidof mdrecoveryd`


Do all this _before_ you glue up the mirror.


# dmesg
<...>
md: minimum _guaranteed_ reconstruction speed: 1000 KB/sec/disc.
md: using maximum available idle IO bandwith (but not more than 100000
KB/sec) for reconstruction.
<...>

# cat /proc/mdstat
<...>
md8 : active raid1 sdb5[2] sda5[0]
      2096384 blocks [2/1] [U_]
      [========>............]  recovery = 43.2% (907584/2096384)
finish=0.3min speed=50421K/sec
<...>


Don't recommend this if your server is I/O intensive and in production
use. Massive performance degration while reconstructing.


SW-RAID rules. :-)


Regards,
 Morten


-- 
morten tørmoen, morten at basefarm.no, +47 97 77 47 77
basefarm as, http://www.basefarm.no, +47 40 00 41 00