For testing purposes we used SRDF to duplicate the DB and logs and
successfully hot split the R1 and R2 several times. The DB always went
into recovery mode, but would start. If you split all of the R2's at
the same time it is the same as crashing the host, not the best thing,
but workable.
If you are running sync SRDF then you will not see a difference while
writing if you use TSM DB mirroring. A Symm will wait for the remote
Symm to commit the write to cache before returning to the host that the
write is complete. TSM may read from either mirror, so that could be a
little slow.
Andy Huebner
-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Shawn Drew
Sent: Thursday, June 19, 2008 2:31 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: [ADSM-L] TSM DB and SRDF
The recent talk about srdf and dr reminded me of our situation
Layout:
- 2 Datacenters with a routed SAN (90 miles a part)
- TSM DB is on DMX that is setup with SRDF in sync mode to the remote
site.
- The DMX luns are assigned to the AIX host, and formated with JFS2.
- The log volume does share one of the luns with part of the DB. (I'm
not
sure if this is a big deal or not)
- VTL's and library managers at both sites. Primary pools at one site,
copypools at the other.
I tested an srdf split, while TSM was running, and attempted to bring
TSM
up at the remote site. It was not successfull, and a DB restore would
have been required.
We re-established and split again with TSM down. This time it worked
fine.
When this was originally implemented, the project owners claimed that
SRDF
was a supported solution. After this test, I called IBM to verify it,
and
support said the only form of DR that is supported is a database
restore.
Questions:
Is there any trick to get this working right?
Do I have to have the log on a separate lun? maybe different srdf group?
Should I be running this in Async mode?
I think the 90 mile separation prevents me from using TSM to mirror the
volumes. This would introduce a big performance hit, right ?
Regards,
Shawn
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