constant zfs data corruption

[Zaphod Beeblebrox]

On Mon, Oct 20, 2008 at 1:32 PM, Jeremy Chadwick <koitsu at freebsd.org> wrote:

> On Mon, Oct 20, 2008 at 03:18:01PM -0200, JoaoBR wrote:
> > On Monday 20 October 2008 15:03:14 Chuck Swiger wrote:
> > > On Oct 20, 2008, at 9:48 AM, Jeremy Chadwick wrote:
> > > > Hm... I thought we determined earlier in this thread that the OP is
> > > > not
> > > > getting the benefits of ZFS checksums because he's not using raidz
> > > > (only
> > > > a single disk with a single pool)?
> > >
> > > He's not getting working filesystem redundancy with the existing
> > > config and is vulnerable to losing data from a single drive failure,
> > > agreed.  But the ZFS checksum mechanism should still be working to
> > > detect data corruption, even though ZFS cannot recover the corrupted
> > > data the way it otherwise would if redundancy was available.
> > >
> >
> > all right and understood but shouldn't something as fsck should correct
> the
> > error?
>
> No.  You're using ZFS, not UFS.  fsck will not work.
>
> In the case of underlying data corruption on ZFS, there is no way to fix
> it unless you have mirroring or raidz in use.
>

Assuming the whole disk isn't bad and without knowing where (how far away)
ZFS puts things when you do this, setting "copies=2" or "copies=3" on a
non-redundant disk/pool/filesystem will allow ZFS to recover data if one of
the copies is still good.