In my experience this mostly depends upon what it is you are backing up.  In my 
world SQL backup containers compress 90% and thus are handled wonderfully by 
the compress asm.  However my file servers which have hundreds of thousands of 
small files do not respond all that well to the compress asm.  What comprises 
that 570G?

I'm pretty sure there is no all or nothing requirement for compression.

I think someone suggested in the past testing with bigasm to understand 
hardware compression/compress asm interactions under a specific set of hardware.

--Shawn

-----Original Message-----
From: EMC NetWorker discussion [mailto:NETWORKER AT LISTSERV.TEMPLE DOT EDU] On 
Behalf Of MIchael Leone
Sent: Monday, February 25, 2008 11:46 AM
To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
Subject: [Networker] Compression on Win2003 servers question

I have a Win2003 server, NW 7.4 SP1, using an HP SDLT autoloader. Total size of 
backup is about 600G (589G, according to mminfo). We'd like to do a full backup 
every day. However, I seem to be averaging 4 tapes (3 full tapes, and 25% used 
on the last) every day. Now, an SDLT tape is 160G native, up to 320G 
compressed, so 600G would need 4 tapes native (3 and
3/4 or so, according to the math).

IOW, it doesn't appear as if compression is being used, or just barely used. I 
see nowhere in NW how to turn on hardware compression on the autochanger. Am I 
just missing it?

I did change to using the "NT with compression" directive, which didn't seem to 
affect the output; I am still getting 3.25 tapes per day used.

My question: I am backing up 3 servers, 2 of which were set to use the 
compression directive, and 1 was not (this last server is very small, and 
doesn't significantly add to the total). Do all group members need to use the 
same compression directive, else NW won't compress? It shouldn't be a problem 
to make all 3 servers use the compression directive, but I thought I could use 
it only on the server that needs it (one server accounts for about 570G of the 
590G total).

Thanks

--
Michael Leone

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