On Wed, 16 Dec 1998 [EMAIL PROTECTED] wrote:
> > The resync uses all available unused I/O bandwidth. You cannot speed that
> > up, besides adding faster hardware :)
>
> It doesn't seem to... when the mke2fs is going and pounding the drives
> all 9 access lights are pegged, but the background resync only writes
> to the drives around once a second, not pegging the drives at all...
> I figured that was a "feature", but is what I'm seeing wrong?
the background resync writes to the disk continuously if you dont use the
array. If you have finished using the array, it will not immediately start
resyncing, but will delay for 1 second. (a reasonable timeout) The point
is that 'small idle periods' are pretty common, a process goes sleeping or
just gets delayed a bit doing CPU-intensive work. In that case it's not
justfied to start resyncing yet, so we only restart the resync when the
IO-subsystem is completely 'IO silent' for a _full_ 1 second window. Since
there might be many (unrelated) IO subsystems in the system, the 'idle'
distinction is made per major device.
if you are worried about the speed of resync, and/or the system is so busy
that it has no idle IO bandwith, then you can increase the 'guaranteed
bandwith' allocated to resync, which is currently 100K/sec/array via
/proc/sys/dev/md/speed-limit.
-- mingo
