Compression Problems with Windows NT, Backup Exec, DDS4

[Sky Cree]

Hi,
My system information is as follows:
File server: Windows NT 4.0 sp6
Tape Backup Software: Veritas Backup Exec 7.x for Windows NT
Tape Backup Drive: HP SureStore DAT 40 DDS4 (C5686A)
Tape Media: HP DDS-4 40gb data cartridge

I have almost 30gb of data to backup 2 times per week. Once the backup
process reaches just over 20gb the Backup Exec software requests a 2nd
tape. With a 40gb tape, and hardware compression enabled, shouldn't
the entire backup fit on one tape?

* I have verfied that hardware compression is enabled.
* I have attempted to change the block and buffer size.

Has anyone else experienced a problem similar to mine? Any suggestions
or ideas?

Thanks

 

[CWatters]

Check the spec carefully for your tape. I'm sure many say 20Gbyte in small
print and "40 GByte before compression" in much larger print. Typically
they are very optimistic about how much that compression saves. It's not
usually a factor of 2.. Don't forget you can't compress jpg or mpg files any
further so if a lot of your data is images or movies then the compression
won't have any effect.