RE: Removing an ASP

Bill,

Get a copy of the Backup and Recovery manual for your OS/400 release.
You're right, it is a DST function that you're looking at and the disk
procedures are well documented in that manual.  Depending on how full
your disks are, you might be able to do it in a single pass.

In general what you will do is:

- logical remove of drive.  (this will pump data to other drives in the
ASP)

- remove drive from ASP2.

- add drive to ASP1.

If you are comfortable that you can empty ASP2 before you add drives to
ASP1, then you can just remove ASP2 and add the drives to ASP1.  This
assumes that all your stuff will fit on the four drives.

The above may be somewhat oversimplified, but if you get hold of that
manual, you should be able to come up with a good plan.  Your diagnosis
of the problem sounds reasonable, you have four disk arms over data that
used to be accessed by eight arms.

It is also possible that you are only writing RAID parity bits to four
drives.  If that is the case, you could get a marginal increase in
performance by switching to eight drives with parity.

Regards,
Andy Nolen-Parkhouse


> On Behalf Of Bill
> Subject: Removing an ASP
> 
> I recently did a changeout of our disks.  There were 8 small drives in
> ASP 1 and 4 larger drives in ASP 2.  This layout worked perfectly for
> what I needed.  Now, I have 4 big disks in each ASP.  There is only one
> parity set.
> 
> I am noticing performance problems and I would imagine it's because I
> only have 4 drives in ASP 1 and am experiencing disk contention.  I'm
> sure that if I had only one ASP and all 8 drives committed to it that
> my performance would greatly improve.  What would be the best way to do
> this?
> 
> I know how to move libraries from one ASP to another, but the question
> would be how to do this and move drives between ASPS.  Is this a DST or
> SST function?  Do they have to move as a set of four at one time, or
> could I move one disk at a time?  If they have to move 4 at a time,
> then either I move the libraries beforehand and then restore -or- I do
> a save and restore of everything in ASP 2.
> 
> What are your recommendations?
> 
> Bill