DLT Hardware compression lies!

[Pipeline]

Hi.

I have Veritas Backup Exec 8.5 on Windows 2000 Professional. Using a Compaq 20/40 GB DLT for backup. Device has hardware-compression checked. Backup Exec log file reports that hardware-compression IS enabled, but only writes 20GB to a tape, then asks for a 2nd cartridge.

Any ideas on how to get the reported 40 GB written to tape?

I've already applied the latest device drivers from Veritas.

Thanks.

 

[dellboy]

It depends on the type of files you're compressing whether you do infact get any compression what-so-ever. I'm running 40/80's and get little over 50Gb on the tape. I have hardware or software running, I was informed by someone else on this site that compression is a rather large ball park. As I said, in my experience I have 50GB on a 40/80 tape.

Good luck

 

[2ffat]

The high compression number on all tapes, not just DLTs, are for complete compression. Most files don't compress that much. Some files like executable won't compress as much (if at all) as ascii files. It really depends on what you are backing up that determines how well your compression works.

If you really want a test, see if hardware compression works any better than software compression. Your tradeoff may be speed vs. amount of compression.
James P. Cottingham

I am the Unknown lead by the Unknowing.
I have done so much with so little
for so long that I am now qualified
to do anything with nothing.

 

[pbxman]

Wow - you're using a high-quality DLT type 3 tape right?

We have the same setup here Quantum 8000 40/80GB. Compression is enabled, and we have to manually select (everyday) 40 with the buttons on the front of the drive, and Density Override.

..if this is your drive, make sure you manually select 40, and Density Override, and try again.

We've successfully backed-up 93+ GB of data on our 40/80 drive & tape.
Pbxman
Systems Administrator

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