If you are using compression (hardware or other), turn it off for this backup
set.
Ray
-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
David Longo
Sent: Tuesday, April 27, 2010 2:44 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: [ADSM-L] Backing up Light Speed compressed files
I have never been concerned with compressed files, never used compression on
TSM - except on my LTO tapes.
Now, we have a new situation. We have had a client with SQL DB and the DBA's do
the dumps to disk and I pick up. (Can't use TDP SQL, long story.) The dumps
were lately (6) 200 GB files, total 1.2 TB and growing daily. Took about 11
hours to backup directly to LTO2 tapes.
DBA's just implemented using Quest's Light Speed using their Level 4
compression - whatever that is. The dumps are now (4) 62 GB files, so about a
5 to 1 compression.
The TSM backup took much less time, but not as much less as expected.
When the offsite copy was made, LTO2 to LTO2, I found out why.
For a certain file size, it takes twice as long to back it up for a compressed
file as an uncompressed file.
For more info, on the LTO2 tapes, before we would get just over 700 GB on them,
now just over 200 GB. (Using q vol stats). I kinew it would be less obviously.
Anybody know why takes twice as long? Is there a way to speed it up?
Thanks,
David Longo
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