ADSM-L

compression issue

1996-06-21 15:50:32
Subject: compression issue
From: David Bohm <bohm AT VNET.IBM DOT COM>
Date: Fri, 21 Jun 1996 12:50:32 MST
Hello:

Yes the data does get compressed twice, BUT you get very little if any
advantage from the hardware compression.  This means your tapes will hold
a lot less data than your marketing rep told you they will.  The published
figures for tape take into consideration that they expect a 2-1 to a 3-1
compression ratio.  On the client size ADSM uses a fairly good compression
algorithm.  The compression ratio you get will be somewhat comparable to
using the UNIX compress command.

The client compression is a tradeoff between network bandwidth utilization
and cpu utilization on the client.  My recommendation on using client
compression depends on where your bottlenecks occur in the backup.  If you
have a lot of extra network bandwidth then you are slowing down processing
by doing client compression.

Hope this helps - David Bohm, ADSM technical support
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