[Ocfs2-users] Some questions about ocfs2

[Ulf Zimmermann]

> -----Original Message-----
> From: Sunil Mushran [mailto:Sunil.Mushran at oracle.com]
> Sent: 04/25/2007 10:31
> To: Ulf Zimmermann
> Cc: ocfs2-users at oss.oracle.com
> Subject: Re: [Ocfs2-users] Some questions about ocfs2
> 
> # debugfs.ocfs2 -R "stats -h" /dev/sdy2 | grep "Cluster Size"
>         Block Size Bits: 12   Cluster Size Bits: 17
> 12 = 4K
> 17 = 128K
> 
> Have you tried stracing the process?
> # strace -tt -T  -o /tmp/strace.out  ...

Yes, strace shows shows most time is spent in lstat64 (> 99%), where
average execution time on ext3 is < 60 usecs/call while on the ocfs2
volume it is > 500 usecs/call.

> 
> Ulf Zimmermann wrote:
> > Is there a way to see how a file system was formatted, i.e. the
block
> > size and cluster size? I currently have a 2TB file system, of which
> > about 840GB are in use by around 9 million image files. Average size
of
> > these images is 60-100KB. Currently our production servers still
have
> > separate file systems on ext3 and we are doing nightly rsync from
there
> > to this ocfs2 volume. This currently takes ~6 hours, which seems a
tad
> > slow. The system spends most time during writing files which have
> > changed on the production servers, with high I/O wait.
> >
> > The SAN this ocfs2 volume is on is pretty much idle, I only see up
to
> > about 20MB/sec traffic and the two nodes which have this volume
mounted
> > have a private GigE interconnect setup for cluster.conf.
> >
> > Any tips on how to debug where this slowness comes from? Or even
> > suggestion to use another cluster file system for a scenario like
this.
> >
> > Regards, Ulf.


Regards, Ulf.

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