[Linux-cluster] Achieving a stable cluster with a 2.6.21 kernel

[Steven Whitehouse]

Hi,

On Fri, 2008-04-11 at 09:05 -0700, Craig Johnston wrote:
> On Fri, Apr 11, 2008 at 1:08 AM, Steven Whitehouse <swhiteho at redhat.com> wrote:
> > Hi,
> >
> >
> >
> >  On Thu, 2008-04-10 at 14:27 -0700, Craig Johnston wrote:
> >  > We would like to achieve a stable GFS/GFS2 cluster configuration using
> >  > a non-Redhat distribution that is based on a 2.6.21 kernel.  Our first
> >  > attempt was to obtain the Fedora Core 7 source rpms for the various
> >  > components (cman, rgmanager, openais, etc.).  We were successful in
> >  > incorporating these packages into our distribution, and creating what
> >  > should be a working cluster configuration with multiple nodes sharing
> >  > a set of GFS2 file systems from an iSCSI SAN.
> >  >
> >  > The problem is that it is all very unstable, takes forever to
> >  > start-up, and locks up under even small load.  We would like to move
> >  > to a more recent version of the cluster suite and update the kernel
> >  > gfs2 and dlm modules for a 2.6.21 kernel.  We need to stick with
> >  > 2.6.21 for other reasons (vendor support mostly), and we figure if it
> >  > all can be back ported for RHEL5.1 (2.6.18) it should be doable for
> >  > 2.6.21.  We just don't know where to start.
> >  >
> >  > Any advice on how we might proceed on this process would be greatly appreciated.
> >  >
> >  > Thanks,
> >  > Craig
> >  >
> >  If you want to use GFS2, then try F-8, or rawhide with the most uptodate
> >  set of packages. I would not recommend using a kernel that old for GFS2,
> >
> >  Steve.
> 
> Do you think we could be successful in patching up the GFS2/DLM
> modules in our 2.6.21 kernel to bring it up to a more recent version?
>  How coupled is the GFS2/DLM code to the rest of the kernel?  We have
> a number of machines running CentOS 5.1.  Does it seem feasible to
> select the applicable patches from that distribution and apply them to
> a 2.6.21 kernel (with some tweaks no doubt)?
> 
> Craig

Not easily. One of the bugs since then was solved by a change in the VFS
so that its not just a question of applying patches to gfs2 on its own.
The version of GFS2 in RHEL has a different fix for this problem though,
so you might be able to borrow that. Either way its not going to be an
easy task and using a more recent kernel would be a much quicker way of
getting a more stable GFS2,

Steve.

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