neither show you how full each tape is (guessing they were different
tapes). with software compression, you got 2.5:1, so 99 gb is written
on the tape, which may have made the tape 1/2 full. with the hardware
compression, 250 was written to tape, and the tape may still be only 1/2
full or less. you would have to do another backup, and see if another
250 gb can fit on the tape. then you'd get 500gb on a 200gb tape, which
would be 2.5:1 compression. you'd at least expect to get another 150gb
on the tape, which would be 400gb total, which would be 2:1.
compression varies by type of data. we get over 3:1 on some backup
tapes. you need more testing before you conclude anything.
good luck,
jerald
-----Original Message-----
From: veritas-bu-bounces AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On Behalf Of Lakshmi
Sent: Wednesday, March 25, 2009 2:15 AM
To: VERITAS-BU AT MAILMAN.ENG.AUBURN DOT EDU
Subject: [Veritas-bu] Reg: LTO3
Hi All,
Im facing a similar issue. We have LTO2 tapes which has native capacity
of 200 GB and compressed capacity of 400 GB.
Did the following tests to check which compression can help in our
environment.
Actual data size 250 GB
With software compression enabled, data written on tape is 99 GB
With hardware compression enabled , data written on tape is 250 GB
So, should i conclude that h/w compression is not useful or is there
something wrong with the drive.
Regards,
Backupadmin
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