ADSM-L

Re: FIVE questions for TSM 4.1.2 (server on AIX, clients on Windo ws)

2001-02-23 13:26:54
Subject: Re: FIVE questions for TSM 4.1.2 (server on AIX, clients on Windo ws)
From: "Prather, Wanda" <Wanda.Prather AT JHUAPL DOT EDU>
Date: Fri, 23 Feb 2001 13:27:12 -0500
1.      When TSM performs incremental backups, does it backup the ENTIRE
file (at a file level) or does it only backup the CHANGES to the file (at a
binary level)?  EXAMPLE: When backing up our primary file server that
contains users' home directories with MS Exchange *.pst and *.pab files that
may be quite large, will it only backup the small changes to those large
files?

2.      When backing up MS Exchange files such as *.pst and *.pab, does it
require them to be closed so that it can have access, or will it back them
up while they are opened?  EXAMPLE: When (using the above example) TSM runs
it's backups, will the "Access Denied" message appear when it tries to
backup "user123.pst" because the user stayed logged in over night.

We have lots of large .pst files.  I mean REALLY large.  And yes, Microsoft
locks them while in use, and TSM can't back them up.

TSM can back up files that are OPEN, but Microsoft has two kinds of locks,
OPEN and OPEN EXCLUSIVE, and TSM can't get past an OPEN EXCLUSIVE.  Neither
can anything else, short of some 3rd party open file manager.  If a Windows
application can't copy the file, TSM can't copy it, period.  However, we
have found that with Outlook, Outlook does release the locks periodically.
You can have Outlook open, and your .pst files won't stay always locked if
they are not actively in use.  (The .pab file is always in use.)

We even experiemented with a C program invoked from PRESCHEDCMD to try and
force Exchange to shut down before the TSM backup, but never got one that
would work reliably.  The only guarantee is to set up your backup schedules
for overnight and tell your users to LOG OFF (or at least shutdown Exchange)
before they leave.

Or another thing you could do, if you really wanted to, is to create an
autoexec.bat (or whatever that equivalent thing is on Win2K, I don't recall)
that would run a dsmc selective backup on your .pst files when the user
starts up, then open EXCHANGE for them after the backup is done.  Or
something like that.

FWIW,
At least with the old Exchange client (as opposed to the new OUTLOOK),
Exchange used to compress the .pst files regularly while you weren't
looking.  So I think even if you used the TSM 4.x feature to back up only at
the byte level, it wouldn't help because more of the file would change than
you expect.  I had thought about trying it because we have people backing up
.pst files that are 1GB plus (yep, GIGABYTES of old mail...).  But I but
have never gotten further than musing about it.

************************************************************************
Wanda Prather
The Johns Hopkins Applied Physics Lab
443-778-8769
wanda_prather AT jhuapl DOT edu

"Intelligence has much less practical application than you'd think" -
Scott Adams/Dilbert
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