From: aru.arunasalam@us.abb.com
Date: Wed Jun 12 2002 - 11:54:39 EDT
Many thanks to all who responded to my query below:
HELP QUERY
----------
>
> We have a Compaq EMA16000 RAID array with HSG80s connected to a number of
> Tru*64 clusters via a FibreChannel. One of the Clusters (C1) has a RAID5
based
> Cluster File System - primarily used for a Oracle RAC database. Because we
are
> short of disk space on another cluster (C2) for a different Oracle RAC, we
> want to share some of the disk space. That is we want to use the available
> disk space on the C1 file system for cluster C2. Is it possible to mount the
> same RAID5 volume on the C2 cluster as well? If not, do you have any other
> suggestions as to how we might share this RAID 5 volume between 2 clusters
for
> Oracle. data. As you may have guessed, we are not in a position to add more
> disks to this RAID array.
RESPONSES
-----------------
"O'Brien, Pat" <pobrien@mitidata.com>
the only supported method is to cluster both clusters together. I have been
investigating similiar question, with a minor difference. I wnat to mount
a read/write hsg80 disk read only on other clients within the san. Though
most agree it is not suppported, this will probably work in read only mode.
The difference for what you want ot do is you don't have a lock mgr between
the 2 clusters to control updates where this does not matter for a read only
fs.
Michael Wheelock
Integris Health
Hi,
The short answer is that you can't share it in the current setup. If you
had used the hsg80 partions (ie. Cut that raid drive in half and created two
lun's) then you could share it to each separately. This still isn't the
sharing you were thinking about though. If you have to have that kind of
sharing, the only real answer is combining the clusters.
"Davis, Alan" <Davis@tessco.com>
No, you can't share the same filesystem. You can, however, reorganize the
disks and use SSP (at the hsg) and zoning (at the switches) to make disks
available to each of the clusters. Using LSM and ADVfs to maximize space
utilization helps.
It's well documented that the disks must be visible to only one cluster, the
daemons that manage the CFS for each cluster would each try to manage the
same space. This just won't work.
Stuart Whitby <swhitby@legato.com>
NFS. You can't mount this directly, though you may be
able to take a backup, unmount the filesystem, recreate
it as two filesystems, then restore from backup again.
There is no way you will ever be able to "share" a
single volume directly between two or more machines.
This will always require one machine to have full control
over the data.
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