>> On Thu, 23 Feb 2006 10:48:06 -0500, Dave Zarnoch <zarnocd AT 
>> NATIONWIDEPROVIDENT DOT COM> said:


> I calculated that our DB is @61GB
> The manufacturer says the tape can hold 50GB compressed

> What do you think is happening?

Most tape vendors use 2.mumble for their expected compression ratio.
Database backups tend to be extremely compressible, so tend to be much
better than that.

For some examples, my original 3592 drives, 300G raw capacity, are
"full" at 450-500G when filled with random filesystem data.  When
they're holding TSM DB backups, they are "full" at 1.2TB.  When
they're holding DB2 database backups, they don't "Fill up" until more
like 1.7TB.

So don't worry too much about it, and if you want to prove that you've
got it all, test a restore somewhere.


- Allen S. Rout