[Linux-cluster] Starter Cluster / GFS

[Jeff Sturm]

> -----Original Message-----
> From: linux-cluster-bounces at redhat.com
[mailto:linux-cluster-bounces at redhat.com]
> On Behalf Of Nicolas Ross
> Sent: Wednesday, November 10, 2010 11:22 AM
> To: linux clustering
> Subject: Re: [Linux-cluster] Starter Cluster / GFS
> 
> > Performance-wise, GFS should should be OK for that if you are
running
> > with noatime and the operations are all reads. If you end up with
> > write contention without partitioning the access to directory
subtrees
> > on a per server basis, the performance will fall off a cliff pretty
quickly.
> 
> Can you explain a little bit more ? I'm not sure I fully understand
the partitioning into
> directories ?

We had to make similar changes to our application.

Avoid allowing two (or more) hosts to create small files in the same
shared directory within a GFS filesystem.  That particular case scales
poorly with GFS.

If you can partition things so that two hosts will never create files in
the same directory (we used a per-host directory structure for our
application), or perhaps direct all write operations to one host while
other hosts only read from GFS, it should perform well.

-Jeff