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Le 14/10/2014 18:17, Gregory Farnum a
écrit :
On Monday, October 13, 2014, Lionel Bouton <lionel+ceph@xxxxxxxxxxx>
wrote:
[...]
What could explain such long startup times? Is the OSD init
doing a lot
of random disk accesses? Is it dependant on the volume of data
or the
history of the OSD (fragmentation?)? Maybe Btrfs on 3.12.21 has
known
performance problems or suboptimal autodefrag (on 3.17.0 with
1/3 the
data and a similar history of disk accesses we have 1/10 the
init time
when the disks are in both cases idle)?
Something like this is my guess; we've historically seen
btrfs performance rapidly degrade under our workloads. And I
imagine that your single-disk OSDs are only seeing 100 or so PGs
each?
Yes.
You could perhaps turn up OSD and FileStore debugging on one
of your big nodes and one of the little ones and do a restart
and compare the syscall wait times between them to check.
-Greg
Will do (have to lookup doc first).
Thanks for the suggestions.
Lionel
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