ADSM-L

Re: ADSM Backup Directly to 3590 Tapes -Reply

1997-06-05 20:47:22
Subject: Re: ADSM Backup Directly to 3590 Tapes -Reply
From: Wayne Gorton <wayneg AT AU1.IBM DOT COM>
Date: Thu, 5 Jun 1997 20:47:22 -0400
In our situation we have a 3494 with 2 3590's & a primary storage pool of 216
Gb. We backup about 44Gb each night from 18 nodes all at the same time. The
backup to tape takes about 90 minutes to run, but there is only 40 minutes of
transfer time. I think this is due to the database io wait. Backup to disk
takes about 2 & a bit hours. We put this down to database io. We use the tape
drive limitations i.e. backup to 2 tape drives, to  govern the database hits.
In the future we are going to spend a little time tuning the database.

A question arises, do the 2 tape drives do 2 backups at a time (from start to
finish) or does it backup any file from any node that is ready to send it at
the time? If it is the second, the tapes would be horribly fragmented.
Any clues

Role:                               Unix System Administrator
Style:                              The Thinking Man's Clown
Name:                               wayneg AT au1.ibm DOT com
Life:       "Imagination is more important than knowledge"   Albert Einstein


        ADSM-L AT VM.MARIST DOT EDU
        06/06/97 02:06
Please respond to ADSM-L AT VM.MARIST DOT EDU @ internet


To: ADSM-L AT VM.MARIST DOT EDU @ internet
cc:
Subject: ADSM Backup Directly to 3590 Tapes -Reply

Hi Tom;

     I have seen similar results.  If you only have one process
backing up then straight to tape can be more efficient.  If several
are running, only one can talk to a tape drive at a time and the
others all have to wait.  You implied that you have multiple drives
in your library so more than one tape can be mounted.  Another
consideration is the time it takes to mount a new tape.  If that
doesn't take too long then you are ok.  Almost any other process
requesting tape access will have higher priority over your backups.
 Restores or migrations may cause your backup to pause.

                                                                      -Bob-

>>> Tom Stewart <tstewart AT US.IBM DOT COM> 06/05/97 09:25am >>>
Hello -

 I'm very new to the ADSM world and have a question concerning
backing up
clients (in my case other AIX servers)
directly to high performance 3590 tape drives in a 3494 library.

I've noticed that when I backup to my disk storage pool located in a
8 way R30
with 2 gig of memory and 120 gig of
SCSI disk space, that backups take about twice a long as going
directly to one
of my primary tape pools, has anyone experienced this?

Is there any advantage of going direct to disk rather than to tape
(other than
speed of recovery of files, i.e. no mount
wait time)?

Thanks for any input.

Tom Stewart
HONE/IBMLink AIX Support
Boulder, Colorado
8/347-2786
tstewart AT us.ibm DOT com
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