Re: MD/RAID time out writing superblock

Chris Webb
2009-09-18T17:08:25Z

Tejun Heo <tj@kernel.org> writes:

> Chris Webb wrote:
>
> > Would such very slow (but ultimately successful) flushes be
> > consistent with the theory of power supply issues affecting the
> > drives? It feels like the 30s timeouts on flush could be just a more
> > severe version of the 15s very slow flushes.
>
> Probably not. Power problems usually don't resolve themselves with
> longer timeout. If the drive genuinely takes longer than 30s to
> flush, it would be very interesting tho. That's something people have
> been worrying about but hasn't materialized yet. The timeout is
> controlled by SD_TIMEOUT in drivers/scsi/sd.h. You might want to bump
> it up to, say, 60s and see whether anything changes.

I'll add that to the list of things to check out on the test machine with a
more disposable installation on it! The 15s flushes we're seeing on
superblock barrier writes do already feel dangerously close to the 30s
hardcoded timeout to me: it's only a factor of two.

Cheers,

Chris.