Data compression of tape

[alandavid]

Hi,
I have a Quantum SDLT-2 300/600GB Tape backup drive.
I am using Veritas Backup Exec 11d and using the windows based drivers for the drive(Windows 2003 Server).
Everytime I try to run a full backup, the tape works fine, although the minute it reaches to 300GB, it asks for another tape.  Since this tape drive claims that it can compress data to 600GB, surely I should be able to at least fit 400GB on one tape?
I have tried enabling hardware and software compression in veritas but it doesnt seem to make any difference.
Can anyone help pls?

alan

[lyon]

 hi alan, I think the maximum is 300GB, none can gurantee that all your data can be compressed.

Lyon

[Ken_Putnam · Accepted solution]

Since this tape drive claims that it can compress data to 600GB, surely I should be able to at least fit 400GB on one tape?

600 GB on a 300GB native tape assumes 2:1 compression, which you will almost never achieve in the real world.  A more realistic rule-of-thumb would be 1.2-1.3:1 (360-390 GB)

if you are getting only 300 GB on a volume, the first thing I would check is from the devices tab, right click the drive and select properties.  Verify that "Enable Compresssion" is selected