[Nottingham] Re: Tape Backup failure

[Graeme Fowler]

On Fri, 11 Jun 2004, David Wolfson wrote:
<snip embarrassing situation :) >
> So I've solved the problem, but am still confused. If the backup creates a
> tarball of ~10Gb, and the tapes say 24Gb on the side, why does it fill up
> the tape?  How can I find the real capacity of the tape?

We used to use 12/24 drive/tape combos at work, prior to the days of 
multi-drive autochanging SuperDLT network backups :)
ISTR that a 12/24 tape can *only* carry 24GB of data if the data is compressed 
by the drive, and is a single uniform repeated character (for example).

The fact that you are precompressing your data (the 'z' tar option) means that 
it cannot then be further compressed by the drive. So that limits the data 
size to about 12GB - I say "about", because it may compress a tiny little bit 
if drive compression is turned on.

Graeme
-- 
If you try to learn something new every day, eventually your brain will fill 
up. What was I saying?