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Tape backup

amjad mosleh
Occasional Visitor

Tape backup

I have a sure store DAT 40 and I have a total amount of 38GB on the server to back up. It is not an autoloader.

i use The HP DDS-4 tape with compressed capacity of 40 GB. The problem is that when I make file selections and they exceed 20 GB and the backup process starts. after 2 hours it sends a message requesting that I should insert another media. I have done that and the backup process finished.

I can do that once a week and wait until the first tape is finished and insert the second tape and go home. And on the rest of the week I can make deferential backup.

Do I have to compress data before I transfer them to the tape so I can do the backup on one tape.

Help me please


P.S. This thread has been moved from  Disk to Tape Libraries and Drives. -HP Forum Moderator

Vincent Farrugia
Honored Contributor

Re: Tape backup


Chances are that you won't compress much anyway.

DDS4 tapes hold 20Gb of data only. The label shows 40GB*, the * referring to "assuming 2:1 compression". If your data is already compressed, it won't yield a 2:1 compression on tape; it will yield to 20Gb storage capacity.

Chances are that your data won't be compressible much.

Tape Drives RULE!!!
Jan Klier
Respected Contributor

Re: Tape backup

You want to make sure that data compression is turned on - it may be selectable in the software and on the drive.

However, even if data compression is properly turned on, there is no guarantee that 2:1 compression can be achieved, as this is highly dependent on the type of data you are backing up.

The only guaranteed thing is that you can back up 20GB (minus some overhead, so typically more like 18-19GB). Anything beyond that will depend on the compressability of your data.

38GB is more than your basic OS - any idea what the other data are made up off?

You should not have to compress data indepdently before the backup - if the data are compressible, the backup software/drive will do this for you. If they're not compressible, doing so wouldn't change things.
amjad mosleh
Occasional Visitor

Re: Tape backup

thanks guys for the fast response, i will try and delete some of those many of them are not used any more