Doug,
I have to disagree with the idea that a diskpool will not help you.
Firstly, if you're using SSA technology, then you should be able to mirror
volume groups, and run the SSA loops through another adapter on a standby
machine for high availability etc. - so your disks shouldn't necessarily drop
out if the machine goes down.
Secondly, even though a diskpool may not contain the entire database that you
wish to restore, it could easily speed things up by reducing the number of tape
mounts required.
To give you an example, we run a J50 with 2Gb of RAM & ADSM v2 and we back up
approx. 50 Gb of database. Using a scheduled job, this takes approx. 3 hours -
with a SHMEM transfer rate of about 24mb/sec.
However, if we run 6 restore jobs in parallel the whole database is restored in
less than 1 hour.
The latest generation of SSA disks/adapters/microcode will 'allegedly' move
160mb/sec. So if you have 14 36Gb disks spread over at least 2 adapters,
feeding your target disks (over another 2 adapters), then you should be able
achieve your target times, because ADSM will mount tapes, to fill in any gaps
in the data, in parallel with valid data moving in from the diskpool.
System tuning will probably give hours of fun. There is a document "Summary of
Tunable AIX Parameters" within Infoexplorer on your AIX install CD. Other
documents of interest may involve Asynchronous I/O
(techsupport.services.ibm.com/rs6k/techdocs/91401108611004.html). However we
are all somewhat in the dark because ADSM uses its own device drivers for ADSM
diskpool disks, so your guess is as good as mine as to what needs tuning. The
only reference to tuning that I've noticed on LISTSERV at MARIST is the
reference to the MBUFS parameter which can be viewed in smit "Characteristics
of the Operating System" screen.
Good luck!
Best Regards
Alex Masters.
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