Rafael,
usually writing to the tape and reading from the tape are nearly
equivalent in processing speed. So one should expect that doing the
backup and restoring take similar amounts of time. Unfortunately in
reality restoring often is much slower than taking the backup. That is
because:
You backup to a diskbased primary pool that gets migrated to tape
later. When restoring you can't expect the data to restore to reside on
this diskbased pool, usually tapes get mounted.
All data from one backup is written sequencially onto the tape in one
session, when restoring you have to read from more sessions (probably on
more than one tape).
Even with "collocation on" data gets spread over many tapes when you
have large nodes. This leads to long restore times due to many tape
mounts, especially when the structure to be restored was grown over a
longer period.

I think with most backup products you need more time for restoring than
for backing up, just think of restoring one full backup and then
bringing back 10 or 20 incremental sessions...

Regards
Michael
--
Michael H. Bartl
Michael H. Bartl
ADAC e.V. (Rechenzentrum, Produktionsplanung und Organisation)
Tel.: (089) 7676-4063, Fax: (089) 7676-8161
EMail: Michael.Bartl AT Zentrale.ADAC DOT de

>----------
>Von:   Rafael Goldschmidt[SMTP:Rafagold AT CANOPUS.COM DOT AR]
>Gesendet:      Montag, 25. August 1997 18:45
>An:    ADSM-L AT VM.MARIST DOT EDU
>Betreff:       Restore speed
>
>Hi ADSMers!
>I want to know if the restore performance or speed is the same as the
>backup speed. I have a customer who suspects that the backup performance
>is OK but the restore performance is poor.  I tell him that restoring is
>the same as saving.  Is this correct?
>Thanks a lot!
>
>
>Rafael J. Goldschmidt
>Buenos Aires, Argentina
>Telefonos / Phones: (54-1) 553 9909 / 421 4782
>rafagold AT cano.com DOT ar
>