Sunday, March 13, 2011

Adjusting ZFS resilvering speed

There are two kernel parameters that can be adjusted if ZFS resilvering speed is too slow/fast:

zfs_resilver_delay /* number of ticks to delay resilver */

and

zfs_resilver_min_time_ms /* min millisecs to resilver per txg */


In some cases the values can be too low or two high (e.g. when using Mirroring vs. RAIDZ).


A boost could be:


# echo zfs_resilver_delay/W0|mdb -kw
# echo zfs_resilver_min_time_ms/W0t3000|mdb -kw


whereas a handbrake is e.g.:


# echo zfs_resilver_delay/W2|mdb -kw
# echo zfs_resilver_min_time_ms/W0t300|mdb -kw

Disclaimer: Use at your own risk. Do not try on production systems without contacting support first.


2 comments:

Anonymous said...

Hi Mika,

Is there any way to contact you, I cannot see any emails or other contact information anywhere.

t: Jukka

Mika said...

You can email me through about.me/mikaborner