UFS2 metadata checksums

[Scott Burns]

Andrew Snow wrote:
> 
> Ideally you would implement complete disk checksumming as a GEOM device.
> 
> Then you could layer geom_mirror on top of it, so that if the checksum 
> fails and returns EIO, geom_mirror can try the alternate device and 
> rebuild the one with the bad checksums.
> 
> That will then complete the feature set implemented by ZFS, but for any 
> filesystem on top of GEOM.
> 
> - Andrew
> 

The geli(8) GEOM class is able to verify sectors (and I believe it 
returns EINVAL on ones that fail), but with a noticeable performance 
impact.  I could certainly see the use for a GEOM class that just does 
simple checksumming.  If gmirror can then be aware of it, that does 
provide functionality similar to a ZFS mirror.

--
Scott Burns
System Administrator
BQ Internet Corporation