ADSM-L

Re: [ADSM-L] Backing up Light Speed compressed files

2010-04-27 16:12:35
Subject: Re: [ADSM-L] Backing up Light Speed compressed files
From: Rick Adamson <RickAdamson AT WINN-DIXIE DOT COM>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Tue, 27 Apr 2010 16:09:30 -0400
Are you still trying to compress data that has already been compressed??
If LightSpeed has already compressed it having your drives set to
attempt compression will cause your issue. Test it by turning the
compression off at the drive level.

Thank you,
~Rick Adamson
Jax, Florida

-----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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