On Tue, Apr 21, 2015 at 11:49 AM, Stefan Priebe - Profihost AG
<s.priebe@xxxxxxxxxxxx> wrote:
> Hi,
>
> while running firefly i've seen that each osd log prints:
> 2015-04-21 10:24:49.498048 7fa9e925d780 0
> xfsfilestorebackend(/ceph/osd.49/) detect_feature: extsize is disabled
> by conf
>
> The firefly release notes V0.80.4:
> osd: disable XFS extsize hint by default (#8830, Samuel Just)
>
> But hammer also mentions:
> osd: verify kernel is new enough before using XFS extsize ioctl, enable
> by default (#9956 Sage Weil)
>
> I'm now confused.
>
> Should i enable this one? Or keep it disabled? What's the advantage /
> disadvantage?
As far as I know the story there is as follows.
extsize was added to try to do a little better on the fragmentation
front, especially in rbd workloads. Shortly after it was added and
enabled by default we hit a bug in xfs and disabled the extsize hint.
After some back and forth with xfs maintainer and a lot of testing by
Sam we found out that the bug only affects < 3.5 kernels. Following that
a safeguard was added to XfsFileStoreBackend so that you can enable
extsize hinting only if you are running a >= 3.5 kernel.
It is now enabled by default so I'd say you should enable it.
Thanks,
Ilya
_______________________________________________
ceph-users mailing list
ceph-users@xxxxxxxxxxxxxx
http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
