Re: Change Raid Settings

Are these SAS drives or SCSI drives? I may be wrong but SCSI drives did
their raid striping over 2, 4 or 8 drives, depending on how many drives
were in the raid set when you first fired it up. For example, if you
started out with a three drive raid set (YUCK!) you will only have your
striping over 2 drives, even though your current set may now have 8 drives
in it. This is why three drive raid sets suck; the striping is only over
two drives. You can often tell how many drives have the raid striping
when you do a WRKDSKSTS. The drives with the raid striping will have less
capacity, because the striping takes away from the capacity. Much like
the question a few weeks ago when the poster wondered how he had drives
with different capacity's in the same raid set.
So, you're planning on going from a raid stripe spread out over 8 drives
to a raid stripe spread out only over 4 drives when you drop down from 8
drives to 7. This could have performance implications. Won't be as bad
as dropping down to a 2 drive raid stripe! (Pass me the short sword
master.)

You may have to stop and restart raid to do all this, see? Don't lose a
drive during this.

SAS drives spread the raid striping over the number of drives initially in
there when you start raid. A three drive raid set should have the stripe
over three drives and not two. Now, if you add a drive the striping
should still stay just over the first drives. A SAS seven drive raid set
(with the 8th drive as a hot spare) should have the striping over all
seven drives.

I hope I am correct.

Rob Berendt