ZFS: Silent/hidden errors, nothing logged anywhere

[Pawel Jakub Dawidek]

On Fri, Jun 12, 2009 at 02:01:57PM -0700, Kip Macy wrote:
> On Fri, Jun 12, 2009 at 10:32 AM, Thomas Backman<serenity at exscape.org> wrote:
> > OK, so I filed a PR late May (kern/135050):
> > http://www.freebsd.org/cgi/query-pr.cgi?pr=135050 .
> > I don't know if this is a "feature" or a bug, but it really should be
> > considered the latter. The data could be repaired in the background without
> > the user ever knowing - until the disk dies completely. I'd prefer to have
> > warning signs (i.e. checksum errors) so that I can buy a replacement drive
> > *before* that.
> >
> > Not only does this mean that errors can go unnoticed, but also that it's
> > impossible to figure out which disk is broken, if ZFS has *temporarily*
> > repaired the broken data! THAT is REALLY bad!
> > Is this something that we can expect to see changed before 8.0-RELEASE?
> 
> 
> I'm fairly certain that we've discussed this already. Solaris uses FMA
> - I don't think that I'll get to a "real fix" any time soon. The time
> that I do have will go to addressing stability problems (memory
> over-allocation, NFS interaction, control directory mounts) all of
> which cause panics. Maintaining them persistently in the label doesn't
> make sense  -  when do you drop them? Would a simple log message about
> the number of checksum errors suffice?

We do log such errors. Solaris uses FMA and for FreeBSD I use devd. You
can find the following entry in /etc/devd.conf:

notify 10 {
        match "system"          "ZFS";
        match "type"            "checksum";
        action "logger -p kern.warn 'ZFS: checksum mismatch, zpool=$pool path=$vdev_path offset=$zio_offset size=$zio_size'";
};

If you see nothing in your logs, there must be a bug with reporting the
problem somewhere or devd is not running (it should be enabled by
default).

-- 
Pawel Jakub Dawidek                       http://www.wheel.pl
pjd at FreeBSD.org                           http://www.FreeBSD.org
FreeBSD committer                         Am I Evil? Yes, I Am!
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