Re: 8203-E4A RAID5 vs. ASP protection

Hello Roberto,

Am 29.02.2024 um 13:59 schrieb 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.

Thanks for adjusting my point of view, that helps a lot in understanding!!

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.

At least V7R2 indeed allows removing disks from an ASP while the system is running.

ASP protection just means that ASP itself is being mirrored or not, you usually don't see "protected" ASPs.

Ah, I see.

So maybe it would show "protected" in a RAID10 configuration? Just for curiosity.

:wq! PoC