Re: [9fans] How to get the diagnostics of fs(3)

[Christian Kellermann <Christian.Kellermann@nefkom.net>]

* erik quanstrom <quanstro@coraid.com> [081015 18:23]:
> > back when i had mirroring via devfs (some three years ago now) i used
> > 'cmp' to verify that the disks were being correctly written to and
> > that no errors have occurred. i ran cmp from the nigtly log at least
> > couple of times a week.
>
> that's a good idea.
>
> when using the mirror device, no write error is issued unless all mirrored
> copies are unwritable.  this would make me nervous since without a
> checksum, it's hard to know which copy is good.
>
> (/n/sources/plan9/sys/src/9/port/devfs.c:697)

Also it means that while the writes may be ok, you will find out
that some sectors are corrupt at the wrong time. For this a cmp
would not be sufficient would it? An interesting thing in my case
is that I got cmp errors from the start, even with freshly nulled
partitions and identical partitions and disks. I still cannot figure
out why.

Cheers,

Christian