Database Migration from DAS to SAN (VMAX)

[sdhaya]

We have our Informix Database ( version 11.x) running on our Primary
Server and replicating the same to our Secondary and Remote Shard
Secondary servers in Linux Platform. ( RHEL5). Currently these
databases are using the DAS storage and we are planning to migrate
from DAS to EMC VMAX. The database size is around 350GB and this is a
real time system and we can only have less than 10min downtime.

We are thinking of doing the following steps for migration to SAN..

Stop the replication between Production and Secondary Database.
Stop Informix in Secondary Database
Present the VMAX LUN to the Secondary Database Server. ( Change the
devices names. We are symbolic links for informix devices).

Question ?. Once VMAX LUN is presented to the Informix Instance ( VMAX
does not contain any data ). Can we restore the LEVEL 0 Backup taken
from Production Server into the Secondary DB Server ( now in VMAX )
and start the replication.

Once the replication is completed, we would like to stop the
Production application, stop the replication and present the same VMAX
LUN in the production node and point a different LUN to the Secondary
node.

Question ?. Will there be any issue with our replication setup. Can
we still replicate from Production to Secondary node.

Please advise.

Dhaya

[Art Kagel]

I believe that you are saying that the secondary is a MACH11 Shared Disk Secondary (SDS).  If that is correct, your plan is essentially sound, but there are some problems.  One I can think of immediately is the loss of transactions and other modifications made to the original data after the level 0 archive is taken. 

A better plan would be to restore the archive to the new disks, bring up the secondary instance as an HDR secondary in synchronous mode or as an RSS secondary with minimal latency and keep it in sync with the primary until you are ready to shutdown.  Once you have shutdown the primary, also shutdown the secondary.  Then drop and recreate the primary's disk links to the new storage, bring the primary online, and finally bring the secondary back online as an SDS secondary.

Art

Art S. Kagel
Oninit (www.oninit.com)
IIUG Board of Directors (a...@iiug.org)

See you at the 2010 IIUG Informix Conference
April 25-28, 2010
Overland Park (Kansas City), KS
www.iiug.org/conf

Disclaimer: Please keep in mind that my own opinions are my own opinions and do not reflect on my employer, Oninit, the IIUG, nor any other organization with which I am associated either explicitly or implicitly.  Neither do those opinions reflect those of other individuals affiliated with any entity with which I am affiliated nor those of the entities themselves.

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[Neil Truby]

"sdhaya" <dhaya....@gmail.com> wrote in message
news:fbaade9a-50ef-4f29...@13g2000prl.googlegroups.com...

> Question ?. Once VMAX LUN is presented to the Informix Instance ( VMAX
> does not contain any data ). Can we restore the LEVEL 0 Backup taken
> from Production Server into the Secondary DB Server ( now in VMAX )
> and start the replication.

Yes.

> Once the replication is completed, we would like to stop the
> Production application, stop the replication and present the same VMAX
> LUN in the production node and point a different LUN to the Secondary
> node.
>
> Question ?. Will there be any issue with our replication setup. Can
> we still replicate from Production to Secondary node.

I don't really understand how you're going to do this. Your original VMAX
LUN will have been presented to the Secondary server initially. Are you
going to use Volume Manager to slice it up into the volumes needed for
Informix chunks? If so, I'm a bit vague on how you will then present the
same LUN to the Primary and expect the server to "see" its data.

If I was doing this I'd probably use Informix or Volume Manager mirroring to
migrate the primary to the VMAX LUN, then use the method you suggest above
to re-establish HDR.