On Sun, 16 Nov 2008, H. Peter Anvin wrote:
Justin Piszcz wrote:
The sync_speed_max was the default as well until I changed it, once I
lowered
the speed, the system was functional again. By default its set quite high,
this appeared to be the root cause of the problem.
You probably ran out of CPU. 2-disk RAID-6 recovery is very CPU intensive.
-hpa
Yeah, one core was pegged at 100% for the resync, another (md_raidX) process
was at ~35% on the second core. The third and fourth core were unused but
immediately when I start the resync it definitley slowed down the system
quite a bit and hurt interactivity and as I mentioned before *without*
specifying a lower rebuild speed than the system's maximum I/O the system
is unusable until the rebuild completes, perhaps its a combination of
using all of the one core for the resync where raid5 may not? I recall
w/raid5 I did not have to specify a lower limit for max_rebuild KiB/s..
Justin.
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