From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On 
Behalf Of Gill, Geoffrey L.
>I was wondering if anyone was multiplexing backups to a single tape.
>Recently I attended a Veritas class, our "other" new backup 
>system, (yes I
>did ask to stay completely with TSM) and they really touted 
>this as what
>seemed like a very good means of backup. Unless you have the 
>newer faster
>technology tape drives I'm not sure I agree with it but don't have
>experience since disk pools have always been plentiful. I'm 
>not sure I agree
>with it anyway because I believe restores would be slow since 
>data would be
>scattered throughout the tape. What if multiple restores need 
>the same tape?
>Can they run at the same time and if so wouldn't that be even worse?

[sound of hollow laughter]

Veritas doesn't tell you about the sting in the tail of their tape
multiplexing. While it can make for faster backups, particularly with
libraries with a small number of drives, they neglect to tell you that
the de-multiplexing necessary to perform restores makes such restores
considerably slower--as in (sometimes) an order of magnitude slower.

...and after all, I personally don't give a hoot about faster backups;
it is faster *restores* I'm after.

--
Mark Stapleton