Re: zfs questions

[Reinoud Zandijk <reinoud%NetBSD.org@localhost>]

Hi,

maybe a bit late

On Sun, Feb 22, 2026 at 04:43:05PM +0000, Emmanuel Nyarko wrote:
> I am currently working on improving RAID in NetBSD with Greg Oster (oster@),
> currently adding n-way RAID 1, and then add scrubbing. I have it on my To-do list
> to extensively work on ZFS because i’ve seen a few reports and previous discussions
> that were not “good” with ZFS. I wanted to discuss it first before touching ZFS code
> but since it has come up, I am very happy to take on that work.

Would it be difficult to add an ioctl to our RAIDframe that say on detecting
an unrecoverably read error on some RAID disc sector X that allows its caller
to read from mirror 0, mirror 1, mirror 2 etc. (i.e. when its able to tell if
say copy A or copy B is right from whatever low level error) to allow the FS
using it to see what copy is OK/expected and allow the FS then to overwrite
that sector X with the correct copy thus fixing the confusion/corruption?

Maybe i'm barking up the wrong tree but it would be handy for FSes that use
internal corruption detection hashes as they alone can see what block will
have the right hash signature.

With regards,
Reinoud