Tape of 24G only allows 13G on it

[Robertvan]

Hello,

I'm just using BE for the first time.
I have to backup around 20GB, but when I start a full backup, it stops at 13GB and it asks for a new tape.

Is there somewhere an option that I have to (de-)select ?
It looks like it's backing up my dada twice ?

Thanks

 

[SQLBill]

Tape size is estimated. Don't forget the backup is also putting on a header with information about the backup. And there may be a couple of bad block areas.

Look at other threads in this forum and you will see this is a common issue.

-SQLBill

 

[comtec17]

What type of tape are you using?

 

[davidwilson11]

what files are being backed up, simply rd files or files that are already compressed. Also what compression is enabled on the tapes.

what drive and tapes are you using?

 

[davidwilson11]

have you set the back up to reset the archive bit and overwrite all media?

 

[AdmanOK]

I've found that most devices rarely give the higher capacity i.e. a 15/30 tape will generally give somewhere in the middle. The tape has a native capacity of 15gb and a capacity of "up to" 30gb with compression. If you are dealing with files that do not compress well (or files that are already compressed) then you will not get 30gb of files onto the tape.

 

[ss702sh]

AdamOK is correct. 15/30, 35/70, 100/200, 200/400 all are native vs compressed data. If you are backing up data that is about as compressed as it can be...*.jpg, *.zip, *.tar, and a gazillion other file types, then you will always get closer to the native rating on the tapes that you are using. On the other hand, if you have 200 gigs of text files, these will fit on a 35/70 tape since text files compress very well.