zfs i/o error, no driver error

[Andriy Gapon]

on 07/06/2010 13:38 Jeremy Chadwick said the following:
> My understanding is that a "vdev I/O error" indicates some sort of
> communication failure with a member in the pool, or some other layer
> within FreeBSD (GEOM I think, like you said).  I don't think there has
> to be a 1:1 ratio between vdev I/O errors and controller/disk errors.
> 
> For AHCI and storage controllers, I/O errors are messages that are
> returned from the controller to the OS, or from the disk through the
> controller to the OS.  I suppose it's possible ZFS could be throwing
> an error for something that isn't actually block/disk-level.
> 
> I'm interested to see what this turns out to be!

Yes, me too :)
I skimmed through the sources and so far I see at least two possibilities:
1) Decompression error for a filesystem with compression.
Again, I don't know why that could happen if there are no checksum errors or
hardware errors.
2) Successful but short read from disk.
Same thing - I don't know why that could happen.

And I am sure that there are other possibilities too.

-- 
Andriy Gapon