Mike Wilson asks:

>We stopped mirroring our database after we moved all ADSM files to RAMAC II
>DASD. Would you agree with this?

This is a tough one to answer. In the example I gave in my earlier note on
this subject, I mentioned how MIRRORREAD LOG|DB VERIFY can help get past a
problem where the primary copy has a bad page. How the bad page gets there,
I can't say for sure -- it might occur if someone were to, say, bring the
system down without halting ADSM properly (I'm just speculating). With only
one copy on RAMAC (or any RAID device -- doesn't matter who's it is or what
type of RAID), you might not be able to recovery from this kind of error.

Another concern might be, how fault-tolerant is the box? Again, it doesn't
matter who's box it is, but if the box was physically destroyed, there goes
your database.

So mirroring does offer some advantages over RAID. But assuming that you
are doing daily database backups (BACKUP DB recommended with ADSM V2, online
DUMP DB w/CONSISTENT=YES recommended for ADSM V1), even if you lost your
database you could restore to the point of your last backup (with subsequent
changes between the backup and the failure lost).

You'll have to determine what is an "acceptable risk". Considering that the
database and recovery log are the "heart and soul" of your ADSM installation,
I'd suggest that you can't be too careful with them.

RAID boxes are very reliable, so your exposure is a lot less than what it
was on non-RAID devices. There are a lot fewer cases where mirroring will
actually be useful (like in the example I cited earlier), but they do exist.

For what it is worth: in my previous life as an ADSM customer, I had my
database and recovery log on RAID boxes, and I continued to mirror.

Andy Raibeck
ADSM Level 2 Support
408-256-0130