Veritas-bu

[Veritas-bu] reverse of disk staging (staging for restores)

2005-09-08 19:19:34
Subject: [Veritas-bu] reverse of disk staging (staging for restores)
From: cballowe AT gmail DOT com (Charles Ballowe)
Date: Thu, 8 Sep 2005 18:19:34 -0500
Is there any way to cause certain types of restores to stage the
necessary images to disk? Any scripts that get run when a restore gets
kicked off that could be used to do that?

The problem I'm trying to solve:

Lotus notes transaction logs - they're a fixed size of 64M, we get
about 80/day backed up. When a lotus restore runs, it restores the
database from the full and applies the transaction logs since that
point. It requests the transaction logs one at a time rather than in
any form of batch. A restore on thursday with the full on saturday
night needs a significant number (80/day * 4 or so) and each of those
requests, when going to tape, takes about 2 minutes (seek time, read
through image until the file is reached, etc ... luckily mounts aren't
hit often as the tape stays mounted). I'm worried that this will
increase in the future as we're likely changing from 9840 to LTO-3 --
9840B drives have an average seek time around 12sec, LTO are more like
45.

I just caught one of those restores in action and staged the images it
would need to disk and the time to restore each file went to 15
seconds or so - very little of which involved reading the file from
media (<5secs). As it took about 20 minutes to stage each day worth of
transaction logs to disk, and each one is used for about 80 individual
files, this could save quite a bit of time on the restore. Not to
mention wear on the tape drive.

It's easy enough to do, but being the standard sysadmin, I'd just like
to automate it.

-Charlie


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