On 10/31/06, Sixbury, Dan <dsixbury at hrblock.com> wrote:
> How do you determine the efficiency of your tape usage?

The GB used per tape shows up on the Vault reports if you use
vaulting.  It is easy enough to do the math once you have the numbers.
 I don't know of any particular NetBackup function that shows usage by
% or any other efficiency type numbers.

>  ...  i.e. I was just
> asked recently about our use of LTO3 tapes since they can hold up to 800 GB
> compressed, how much we were actually consuming.  i.e. if we are getting our
> money's worth for the larger capacity more expensive tapes.

A big source of tape waste comes from using too many volume pools.  In
many cases there is no legitimate reason to have separate volume
pools.

Too many media servers is a similar problem since each media server
pulls it's own tapes.  If a SAN media server has small incremental
backups, you may prefer to send those over the network to a more
active media server instead of writing directly to tape.

Another source of tape waste come from having too many tape drives
active at once.  Forget compression for a second.  Lets say you have
900 GB you are backing up and 2 LTO-3 tape drives in a library.   If
you have both drives active and they both start at the same time, you
are likely to use 4 tapes (each with a max of 400GB)  to backup the
900 GB.  That is because when the two drives finish writing their
first 400 GB each, they both pull a new empty tape and start writing
to it.   If you had only one drive active, it would take longer but
only use 3 tapes.  Compression changes the numbers a bit, but not the
problem.

Austin