| From: | Matthew Wakeling <matthew(at)flymine(dot)org> |
|---|---|
| To: | Craig James <craig_james(at)emolecules(dot)com> |
| Cc: | pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Weird XFS WAL problem |
| Date: | 2010-06-03 17:14:07 |
| Message-ID: | alpine.DEB.2.00.1006031811340.4083@aragorn.flymine.org |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-performance |
On Thu, 3 Jun 2010, Craig James wrote:
>> Also, are barriers *on* on the RAID1 mount and off on the RAID10 one?
>
> It was the barriers. "barrier=1" isn't just a bad idea on ext4, it's a
> disaster.
This worries me a little. Does your array have a battery-backed cache? If
so, then it should be fast regardless of barriers (although barriers may
make a small difference). If it does not, then it is likely that the fast
speed you are seeing with barriers off is unsafe.
There should be no "just missed the sector going past for write" problem
ever with a battery-backed cache.
Matthew
--
There once was a limerick .sig
that really was not very big
It was going quite fine
Till it reached the fourth line
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