Re: 8203-E4A RAID5 vs. ASP protection

Removing the disk from the ASP does nothing to prevent a RAID5 failure. In
this case, x86 knowledge does not translate to IBM i.
In IBM i, the controller does not hide the disks behind a "volume", it
presents all disks and instead just reduces the presented capacity on each
one to account for the parity protection, that is why you see all the DDxxx
devices in the ASP. You need to replace the failing disk ASAP.
If the disk fails, the RAID will go to a degraded state whether or not you
are using the DDxxx device, because all of those disks are part of the RAID
set. Now, if you went to the DST and removed the disk from the RAID set
(which I'm not sure you can, you can add but remove? never tried it) that
would be another thing altogether.
ASP protection just means that ASP itself is being mirrored or not, you
usually don't see "protected" ASPs.

Roberto

On Thu, 29 Feb 2024 at 08:52, Patrik Schindler <poc@xxxxxxxxxx> wrote:

Hello,

on said machine I got regular messages about an imminent DASD failure.
I've identified the disk (number three) in question and removed it from the
ASP: There plentiful space left without it.

In the "Display Disk Configuration Protection" screen, each individual
disk is listed as "RAID 5" in the "Protection" column, but the ASP itself
is listed as unprotected.

Serial Resource Hot
Spare
ASP Unit Number Type Model Name Protection
Protection
1 Unprotected

1 Y2103QN***** 433C 099 DD001 RAID 5 N

2 Y2103QN***** 433C 099 DD002 RAID 5 N

4 Y2103QN***** 433C 099 DD004 RAID 5 N

5 Y2103QN***** 433C 099 DD005 RAID 5 N

6 Y2103QN***** 433C 099 DD006 RAID 5 N


I'm not sure how to interpret this display. If a disk fails, does RAID5
protection kick in and leave the ASP in usable state? If yes, what is the
meaning of the "unprotected" display for the ASP?

Thanks!

:wq! PoC

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