Re: [RFC] Persistent naming of scsi devices

James Bottomley
2002-04-08T19:07:04Z

mjacob@feral.com said:
> For the current discussion, it seems to me that unlabelled/unimported
> disks/volumes (i.e., ones w/o a UUID) still can be named unambiguosly
> by the unwieldy names because you're likely to put a UUID on them very
> very quickly. Furthermore, a minor amount of effort in userland tools
> can make the manipulation of said names not as much of a problem.

I agree, but there are the edge cases where you can't put a UUID on them.

I think, however, that what the discussion is showing us is that there is no
one universal way to get a unique name for a volume, so what we want is some
type of pluggable infrastructure which allows us to construct a unique name.

As far as persistent binding goes, I think having the ability to persistently
bind the unique name to a device is a useful feature for those of us who don't
want to know what the actual unique name is (or who want a nicer name).

However, nothing should prevent you from passing the name as a string to mount
instead of using persistent binding (even if the string turns out to have to
be a set of hex digits). Perhaps we could even have a user level table of
nice UUID to unwieldy unique name mapping, and you can use a user specified
UUID without having to put anything on the device or partition.

The summary so far, as I see it, is

1) persistent binding might be a user friendly way of uniquely identifying
devices
2) UUID doesn't solve the problem because not everything has one
3) ditto for WWN or EVPID

Another wrinkle is that UUID is partition specific, but WWN etc. are device
specific.

James