On Feb 11, 2014, at 11:11 AM, "Gallas, William N" [off-list ref] wrote:

Hi,

I have a raid 6 unit that takes over 40 hours to rebuild from an HDD fail condition. I have ample CPU cycles available and was wondering
if MDRAID throttles the rebuild speed. 

Yes. It's probably a combination of too small md/stripe_cache_size, and /proc/sys/dev/raid/speed_limit_max and maybe /proc/sys/dev/raid/speed_limit_min. Another possibility is misalignment due to incorrect partitioning of a disk with 4KB physical sector sizes.


Chris Murphy