[OpenIndiana-discuss] Zfs stability "Scrubs"

[David Brodbeck]

On Mon, Oct 15, 2012 at 5:02 PM, Richard Elling <
richard.elling at richardelling.com> wrote:

> There is some interesting research that shows how scrubs for RAID-5
> systems can
> contaminate otherwise good data. The reason is that if a RAID-5 parity
> mismatch
> occurs, how do you know where the data corruption is when the disks
> themselves
> do not fail. In those cases, scrubs are evil. ZFS does not suffer from
> this problem because
> the checksums are stored in the parent's metadata.
>

A similar problem happens for traditional RAID-1 mirrors.  If mirror
verification shows the two disks differ, there's no way of knowing which is
correct.

-- 
David Brodbeck
System Administrator, Linguistics
University of Washington