backups using HP DAT drives

[Guest]

I was wondering does anyone have any experience using HP DAT drives for
backups. My issue is I have a DAT 24 internal drive and I'm having problems
backing up when the amount of data is less than 24GB (approx 19GB). I am
using compression. For a while I was using hardware compression. I was having
issues with that. Now, I changed to software compression.

The backups are failing and the software, which is veritas backup exec, gets
to a point and requests another tape. I put in another tape, but the backup
does not continue. I tried using NT backup in Win2000 server, it also
produces the same issue. I understand that I won't get exactly 24GB on a
tape, but I should be able to get more than 19GB. Any suggestions here would
be helpful.

 

[Guest]

My experience is with dlt's and Veritas Backup Exec, not Dat's. However,
19gig on a 24 gig tape sounds pretty reasonable to me. Consider 2 factors:
some of your files are already compressed or so tightly created that they
cannot be further compressed-jpg's, zips, etc. Also, 2:1 compression,
whether hardware or software, is the maximum compression possible. It
doesn't follow that you will always get exactly 2:1. You don't say how much
data you're trying to back up, but in my experience, getting 2/3 to 3/4 of
the tape's max capacity is the best you can do.

 

[Will Niccolls]

I was wondering does anyone have any experience using HP DAT drives for
backups. My issue is I have a DAT 24 internal drive and I'm having problems
backing up when the amount of data is less than 24GB (approx 19GB). I am
using compression. For a while I was using hardware compression. I was having
issues with that. Now, I changed to software compression.

The backups are failing and the software, which is veritas backup exec, gets
to a point and requests another tape. I put in another tape, but the backup
does not continue. I tried using NT backup in Win2000 server, it also
produces the same issue. I understand that I won't get exactly 24GB on a
tape, but I should be able to get more than 19GB. Any suggestions here would
be helpful.

So does the backup ever fail? If so, what is the error reported? Or does
it just hang for hours when you put the new tape in? How long have you
waited?

If you break it into two backup jobs to two seperate tapes, does it complete
correctly?

How do you know it is 19GB of data?

Will Niccolls