I have heard that you should NOT use AIX JFS Mirroring on Raw Logical
Volumes which are used to house the ITSM Log and Database. Instead, if
you are using Raw Logical Volumes, you should use ITSM's mirroring
facility. What I have heard is that there is a data integrity issue
here. I am not doing this.

But what about doing mirroring at the SSA Adapter level? What if you
create an SSA raid_1 (mirrored, but not striped) array and then put an
AIX Raw Logical Volume on it, and use that for the ITSM Database or Log?
Would this involve the same problems/risks as doing this with AIX JFS
Mirroring? My first guess is that SSA RAID Mirroring would be safe, and
would not involve those same hazards as AIX JFS Mirroring.

Anybody have experience with this?

1. Is it safe?
2. Does it perform better? (It should, by moving the mirroring from
   software into the adapter microcode.)

(The question also applies to SSA raid_10, but for the ITSM DB in
particular, I would expect raid_10 (striped set of mirrors) to perform
slower than raid_1 (just mirroring), so I have no interest in using
raid_10 for the ITSM DB. I do plan to use raid_10 for ITSM Storage Pool
volumes though, which I assume will be OK since AIX JFS Mirroring works
OK there.)

Roger Deschner      University of Illinois at Chicago     rogerd AT uic DOT edu
======I have not lost my mind -- it is backed up on tape somewhere.=====