Re: Unable to restart Mon after reboot

[Christoph Hellwig <hch@infradead.org>]

On Tue, Jul 03, 2012 at 09:44:38AM -0700, Tommi Virtanen wrote:
> We've seen similar issues with btrfs, and others have reported that
> the large metadata btrfs option helps. We're still compiling
> information, but as of right now I hear best performance tends to
> happen with xfs; however, the lead position tends to shift around a
> lot.

Btw, does anyone know which part of the btrfs metadata is hit hard?
It's been a while that I looked at the OSD code, but IIRC it didn't
create too big directories, does it?  For heavy directory operations
XFS filesystems created using large directorit blocks (mkfs.xfs -n
size=64k) will also provide additional benefits.

Also IIRC the OSDs have a directory per VDI image - for that kind of
usage pattern the -o filestreams mount option of XFS should provide
even more performance advatages.  Either way make sure to mount with
-o inode64, and for not so recent kernels -o delaylog.