Re: TDP Restoration Process.

2002-11-25 10:34:24
Subject: Re: TDP Restoration Process.
From: Del Hoobler <hoobler AT US.IBM DOT COM>
Date: Mon, 25 Nov 2002 10:33:15 -0500

Sorry, I am still not quite understanding your position...
... unless you are counting on direct to tape backups.
Are you?  In that case... all of this MAY make more sense.

How are you reducing the "number of restores"?

Each transaction log backup is ALWAYS a single unique 64M object
on the TSM Server, regardless of whether you back them up once
an hour or only three times a day. During a DP for Domino
activate/applylogs, each log backup that must be restored
is asked for individually, in the 64M segement.
It's not like all the logs that were backed up at one time
will get restored in one "chunk" of data.

Now, if they are backed up all at one time... AND they are going
directly to tape, I could see how you might gain efficiency
since the logs will most likely be in sequence on the tape...
... thus possibly reducing the tape head movements...
... and maybe that it what you are pointing out...
Are you?

Like I said... this makes more sense if you are doing the
backups of the transaction logs directly to tape.

...but without direct to tape backup... when those objects
are "migrated" to tape... you are up to the whim of
TSM Server algorithm used on how those are placed on tape and
in what sequence they are placed on tape... and it surely
doesn't do this taking into consideration the sequence
that is best for DP for Domino activate/applylogs...
... even if collocation by filespace is turned on.

And so... if you assume direct to tape backups, and you
back the logs up less often (the result being that many of the
transaction log segments will be in sequence on tape)...
...a lot of this makes sense and will benefit you during restore
because of how the data was sequenced during backup.  I like it...
Is that what you are trying to point out to me?

Sorry if I am not understanding your exact point... (remember, it's Monday)
I want to make sure I understand your point fully... and make sure
there are not assumptions being made on how the objects
are created on the TSM Server based upon when they are backed up.




Del Hoobler
IBM Corporation
hoobler AT DOT com

- Never cut what can be untied.
- Commit yourself to constant improvement.

On Mon, 2002-11-25 at 06:12, Del Hoobler wrote:
> > I am not sure I understand how your solution
> > of backing up the log less often will help.
> > The same amount of data will need to be backed up
> > whether you queue them up or not.

> Think about it, Del. It's not the amount of data that I was trying to
> work around; it's the number of restores I was trying to reduce.
> If you're backing up Domino logs thrice a day, instead of 24 times a
> day, you have 1/8th the number of tape mounts, spin-forwards, restores,
> log replays, rewinds, and dismounts. Since log restores are a
> single-threaded process, and if each log restore requires 4 minutes
> (which is pretty conservative), and you're restoring 5 days' worth of
> logs, my scheme would require an hour for log restoration, versus 8
> hours if you're backing them up every hour.

<Prev in Thread] Current Thread [Next in Thread>