ADSM-L

Re: Making TSM twin-center compliant

2006-09-01 10:01:29
Subject: Re: Making TSM twin-center compliant
From: "Allen S. Rout" <asr AT UFL DOT EDU>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Fri, 1 Sep 2006 10:00:14 -0400
>> On Fri, 1 Sep 2006 13:17:17 +0200, "Loon, E.J. van - SPLXM" <Eric-van.Loon 
>> AT KLM DOT COM> said:

> We are about to implement a second (fallback) IT center on another
> location. The idea is to create a hot standby environment for TSM.
> We are already using a separate copypool which will be moved to the
> new remote location, so if the primary pool gets lost, we have all
> data (up until the last backup stgpool of course) on the remote
> location.  However, in case of a disaster, not only will we have to
> be able to recover clients (from this copypool), but we also need to
> continue backup here.

> This would be no problem if one could promote a TSM copypool to a
> primary pool. In this case one could just continue making (the forever
> incremental) backups, but TSM doesn't offer this function (yet).

Sure it does. In fact, you can do exactly as you describe; biggest
impact will be that the copy stgpools are usually (very) poorly
optimized for client restore.

Think of it carefully: Two TSM servers: PRIM, and COPY; COPY is
housing the offsites.

You lose PRIM, but, since you're good at these things you have the
database backed up offsite.  You restore the PRIM database on hardware
at the remote site.

Immediately at that point, you have access to the data in the copy
pools, and more importantly, you have the -database- that tells you
what you have and don't have.

The next incremental will only copy the data you didn't have as of the
database backup which you used to do the restore.

So, between the time you get PRIM restored at the remote site, and the
time when the first of your clients have gotten their acts together,
you can be RESTORE STGpool ing as fast as your little tape drives can
scurry; as you make progress there (according to your previously
determined list of priorities...) your replacement PRIM becomes better
and better suited to serve the client restores.


>From another perspective: Why "promote" a copystgpool to PRIMARY
status?  You'll just need to re-organize the new PRIMARY pool and then
make a copy pool.  Less work to take the well-organized (for a copy
stgpool) existing copystgpool and make a new PRIMARY.


- Allen S. Rout
- There is no copy, there is no primary.  There is only data.