Need to replace luns/SAN

[Zahid_Haseeb]

environment

rhel 5.3

sfha/dr 5.0 mp4 rp3

two nodes at primary and one at dr site

SAN is going to replace at primary site. would people suggest the best way to move the storage from old SAN to new SAN.

[Marianne]

Simply mirror volumes to new storage, wait for mirrors to sync, then remove original plex.
All can be done online.

See: http://www.symantec.com/docs/TECH66011

[Daniel_Matheus · Accepted solution]

There are different ways of doing this, you can simply mirror like Marianne was suggesting.

If you are using VVR you could add another secondary, or you could use hardware replication like Truecopy for example.

But all this depends on your hardware and environment.

[mikebounds]

I assume you are using VVR as hardware replication usually requires the same hardware at both sites which  won't be the case after replacing SAN at just one site.

Best way is to mirror to new SAN as Marianne says as then you keep DR capability during migration, where as if you just ran app at DR while you replaced SAN at Prod and then resynced, you would have no DR option during migration.

Mike

[Zahid_Haseeb]

Thank you all for kind words.

So my steps will be.

- Take backup first.

- Add new disks to the DiskGroup.

- Establish mirror between old disk(exist on old iSCSI SAN) and new disk(exist on new EMC SAN).

- Wait mirror need to be synced.

- Break mirror when sync completed.

- Remove old disks from DiskGroup.

- Unconfigure old disk luns from cluster nodes.

=================================

@ Marianne

All can be done online.

When we will break the mirror and remove original plex, if the system is a busy system, data can be written on old plex before removing the old plex. So is not that be a offline activity ? Please advise

[Daniel_Matheus]

No it's not. once you break off a mirror all data will be written to the remaining mirrors. The one that you broke off won't be touched anymore.

As you are replacing the SAN on the primary site, you should consider performing this during a quite period as a mirror resync can degrade your i/o performance if the application are also putting a lot of i/o on the LUNs.

In case you see performance degradation you might lower the priority of the task:

http://www.symantec.com/business/support/index?page=content&id=TECH19044

[mikebounds]

This can all be done online, but as Daniel says during the establish of the mirror, as the old disks are being read to copy to the new disks, this can effect I/O performance of your app.  Once the mirror is synced, performance should not be an issue and it shouldn't matter if system is busy when breaking mirror.

Mike

[Marianne]

data can be written on old plex before removing the old plex.

Seems you are concerned that data will be written to plex1 and removed before the write to plex2 has happened?

This is not how mirroring works.

Once mirrors are in sync, data has to be written to both plexes before the write is acknowledged. 
The write is not done to plex1 and then mirrored to plex2.

So, once the mirror is fully syncronized, there is no danger that you will lose any data when plex1 is removed.

If you have VOM in this environment, you can also use the 'enclosure migration' utility.

See http://www.symantec.com/docs/HOWTO36625