[Ocfs2-users] lvm2 not cluster aware - okay, so how should I stripe my LUNs?

[Brian Long]

On Wed, 2006-10-04 at 15:41 -0600, Humpherys Philip D Contr 532 CMMXS/CL
wrote:
> Hi, I'm testing ocfs2 in a 2-node ocfs2 cluster.  I have 12 SAN LUNs
> that I'd like to stripe and mount up as an ocfs2 filesystem.  I've
> been told that because LVM2 is not cluster aware, that it can't be
> used.  I'm trying to make mdadm work.  (using EMC powerpath for
> multipath).  I can create an md raid0 device on one node using
> the /dev/emcpowerxx pseudo-devices, and on the other node the md
> device is there, but it has scanned for the devices, and it shows
> the /dev/sd* devices, not the pseudo-devices that really need to be
> used for multi-path.  

I don't believe anything included in RHEL is supported across clusters
for software RAID.  This means LVM and MD are out of the picture.

Oracle only supports RAW devices, OCFS2 filesystems (one filesystem per
SAN LUN) or ASM.  They also support Red Hat GFS, but only if you use
external locking (GLM).  For a 4-node RAC cluster, you'd need 7 nodes (3
dedicated to locking).  This is because Oracle insists that none of the
RAC nodes participate in the GLM locking.  I believe Oracle may be
certifying DLM, the newer lock manager in GFS, but I'm not sure.

Either way, GFS is an added cost on top of RHEL, but it includes RHCS
and RHCS has cluster-aware LVM (I believe).

/Brian/

-- 
       Brian Long                             |       |
       IT Infrastructure                  . | | | . | | | .
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