[CentOS] variable raid1 rebuild speed?

Wed Jan 12 19:57:24 UTC 2011
JohnS <jses27 at gmail.com>

On Wed, 2011-01-12 at 12:38 -0600, Les Mikesell wrote:
> I have a 750Gb 3-member software raid1 where 2 partitions are always 
> present and the third is regularly rotated and re-synced (SATA disks in 
> hot-swap bays).  The timing of the resync seems to be extremely variable 
> recently, taking anywhere from 3 to 10 hours even if the partition is 
> unmounted and the drives aren't doing anything else and regardless of 
> what I echo into /proc/sys/dev/raid/speed_limit_min or _max.  Is there 
> some way to tell if the drives are going bad or speed it up consistently 
> if they aren't?

echo 100000 > /proc/sys/dev/raid/speed_limit_min

echo 100000 > /proc/sys/dev/raid/speed_limit_max

Should equate to around 100MiBs and I suppose bad sectors or punctured
block will bring it to a crawl also.  Check the disk out with smart.  On
way to tell is keep a "hdparm" baseline.