Re: Removing an ASP -- MIDRANGE-L

In addition to what Andy said:
Performance recommendation
If you want to have RAID infos spreaded over 8 drives, that is, having
the more sophisticated algorhythm with 8 disks in one set instead of
having 2x 4 disk sets, you would have to stop "parity protection" (RAID)
in DST after the drives have been added to ASP1.
This will end your 4 drive RAID set. Then start "parity protection" again
and select all drives in ASP1 at once (if you only have one controller,
this is the only choice), this will setup the 8 drive set then. You will also
notice a smaller loss of capacity, RAID with 8 disks only needs about
10% additional space, while the 4-drive sets needed about 20% of total
capacity to store their "parity info".

HTH. Regards from Germany, Philipp Rusch

Andy Nolen-Parkhouse schrieb:

> 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
>
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