On 07/19/2012 01:06 PM, Calvin Morrow wrote:
On Thu, Jul 19, 2012 at 9:52 AM, Tommi Virtanen<tv@xxxxxxxxxxx> wrote:
On Thu, Jul 19, 2012 at 5:19 AM, Vladimir Bashkirtsev
<vladimir@xxxxxxxxxxxxxxx> wrote:
Look like that osd.0 performs with low latency but osd.1 latency is way
too
high and on average it appears as 200ms. osd is backed by btrfs over
LVM2.
May be issue lie in backing fs selection? All four osds running similar
Our typical experience with btrfs right now seems to be that it works
fast when the filesystem is fresh, but as it ages, it starts to have
higher and higher delays on syncing writes. This does not seem to be
completely deterministic, that is, if you run many btrfs'es, the
symptoms start to appear at different times on different instances.
Is Inktank seeing the slowdown on btrfs volumes with large metadata
(32k / 64k) node/leaf sizes as well, or only on default (4k) sizes?
Vladmir,
What node/leaf size are you using on your btrfs volume?
Hi Vladmir,
We are seeing degradation at 64k node/leaf sizes as well. So far the
degradation is most obvious with small writes. it affects XFS as well,
though not as severely. We are vigorously looking into it. :)
Mark
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Mark Nelson
Performance Engineer
Inktank
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