Ignatios Souvatzis <ignatios@cs.uni-bonn.de> writes:

> > Disks really *should* have unique ids.
> 
> No. File systems should have.

I don't think I completely agree. The operating system shouldn't care
if I have filesystem, a raw device database, or swap on my partition,
and it should work just the same if I move disks (partitions)
around. If I have a mirrored partition the application using it
shouldn't have to care that there are more copies of the information.

On the other hand a filesystem might also want to keep information
about where to find alternative sources for a filesystem, whether it
is on an other disk or another host (let's say you have a multihomed
disk where my end of the scsi-chain is broken but I still can mount
the filesystem via some other network). The kernel disk can't and
shouldn't know anything about this.

/Johan