Re: 8203-E4A RAID5 vs. ASP protection

[Roberto José Etcheverry Romero <yggdrasil.raiker@xxxxxxxxx>]

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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