On 01/17/2013 10:24 AM, Sébastien Han wrote:
Hi Stephan,
- Increase the osdmax value
Well actually this doesn't seem to be necessary because when you issue
a "ceph osd create" the osdmax value is automatically incremented. It
just that a while ago I saw on the ML or IRC that it was a good
practice to do this. And this documentation
http://ceph.com/docs/master/rados/operations/control/ says:
"Set the max_osd parameter in the osd map. This is necessary when
expanding the storage cluster."
Maybe the doc is outdated on this option, I don't know.
- Set “filestore flusher” option to false, in your [osd] section
During my benchmarks sessions I noticed that disabling this option
brought way better performance, at least for old hardware. Fo recent
hardware I haven't seen any difference, but I kept the habit to
disable it. There are some discussions about this option on the ML. As
far as I can remember, it's harmless to disable it.
From the doc here
http://ceph.com/docs/master/rados/configuration/filestore-config-ref/:
I actually have been doing parametric sweeps over the various ceph
tunables to try to see what affects performance. I'll have an article
coming out soonish documenting some of the findings. Typically
disabling the flusher seems to be beneficial on XFS and BTRFS, but it
seems to be the opposite on EXT4.
"The filestore flusher forces data from large writes to be written out
using sync file range before the sync in order to (hopefully) reduce
the cost of the eventual sync. In practice, disabling ‘filestore
flusher’ seems to improve performance in some cases."
Cheers,
--
Regards,
Sébastien Han.
On Wed, Jan 16, 2013 at 7:41 PM, Stefan Priebe <s.priebe@xxxxxxxxxxxx> wrote:
Hello Sebastien,
hello list,
first nice article sebastien ;-) thanks for contributing.
I've two question regarding the tips:
Can somebody explain me why i should do this?:
- Increase the osdmax value
- Set “filestore flusher” option to false, in your [osd] section
Greets,
Stefan
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