[OpenIndiana-discuss] ZFS's vdev state transition

[Bob Friesenhahn]

On Fri, 20 Jul 2012, Ichiko Sakamoto wrote:

> Hi, all
>
> I have a disk that has many bad sectors.
> I created zpool with this disk and expected that
> zpool told me the disk has meny errors.
> But zpool told me everything was fine until I scrubbed the zpool.
>
> Is this designed feature?

Zfs detects hardware-reported write failures, but can/does not detect 
read failures until it tries to read the data.  I have learned that 
zfs does periodically "taste" the data in a few locations as part of 
normal operation (to detect disk errors) but it tries to read from the 
disk as seldom as possible since doing so would hinder performance.

If the disk continually reports that all writes are fine then zfs 
might not discover wrong data for a long time, or until 'scrub'.

Bob
-- 
Bob Friesenhahn
bfriesen at simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/