[Lustre-discuss] Multi-Role/Tasking MDS/OSS Hosts

Andreas Dilger andreas.dilger at oracle.com
Fri Sep 17 12:38:06 PDT 2010

On 2010-09-17, at 13:19, Brian J. Murrell wrote:
> On Fri, 2010-09-17 at 11:10 -0800, Jonathan B. Horen wrote:
>> Yes, but... how, then, am I to view SAN storage devices?
> I'm not sure.  Whatever you can do to present the devices to Linux as
> block devices.  Lustre OSTs and MDTs are Linux block devices.

I think the more informative answer is that the OST is the Lustre name for the ext4-like filesystems on the Linux block devices (regardless of what the underlying storage is).  The OSS is the Lustre name for the node on which these block devices are attached.

>> Am I correct in thinking that these SAN storage devices would be networked to one-or-more OSSes?
> They need to make themselves available as block device(s).

Yes, the SAN devices need to be attached to at least one OSS, but preferably two OSSes to provide high availability.  We recommend against connecting the SAN devices to all of the OSS/MDS nodes, because this increases the configuration complexity and risk of an administrative error, and provides no benefit.

>> Did I misunderstand that RHEL5 sports Lustre-support already in the kernel? 
> Yes, I'm afraid you did.  You will need either one of our pre-built (we
> currently build for RHEL5, OEL5, SLES10 and SLES11) kernels or patch
> your own kernel with the patches.

The patches are needed on the Lustre server kernel, but are not needed on the client.

Cheers, Andreas
Andreas Dilger
Lustre Technical Lead
Oracle Corporation Canada Inc.

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