Re: not all volume types export UUIDs (was: /dev/disk/by-id

[Kay Sievers <kay.sievers@vrfy.org>]

On Thu, 2008-07-03 at 08:33 -0700, Matthew Dharm wrote:
> On Thu, Jul 03, 2008 at 05:12:57PM +0200, Kay Sievers wrote:
> > On Thu, 2008-07-03 at 06:42 -0700, Matthew Dharm wrote:
> > > On Thu, Jul 03, 2008 at 11:02:46AM +0200, Kay Sievers wrote:
> > > > On Thu, 2008-07-03 at 07:30 +0200, martin f krafft wrote:
> > > > > also sprach Kay Sievers <kay.sievers@vrfy.org> [2008.07.02.1806 +0200]:
> > > > > > All are only unique per namespace/bus, and should better not be
> > > > > > mixed.
> > > > > 
> > > > > Well, but that's my point I suppose. Why do we have to treat the
> > > > > same drive differently, whether it's on the ATA bus or the USB bus?
> > > > > 
> > > > > My reason for bringing this up was that I was trying to boot off
> > > > > a harddrive via USB and had to change all the links, rather than
> > > > > just watching the system boot off the same disk it has always booted
> > > > > from.
> > > > 
> > > > So, what id's/symlinks is the same disk showing for ATA and USB in your
> > > > case?
> > > > 
> > > > Only advanced USB bridges read the number from the actual disk, I have a
> > > > bunch of enclosures here, which show all different id's for the same
> > > > disk inserted. Also usb-storage needs to encode the target and lun
> > > > number in the id, for multi-slot devices, so I do not think that will
> > > > work.
> > > 
> > > Isn't devlabel the technology that is supposed to be used for this sort of
> > > scenario?
> > 
> > No, that is replaced by /dev/disk/by-label/*
> 
> Well, yes... I mean, you can *use* the label on the partition in a number
> of ways.
> 
> But, my point was that instead of trying to ID a disk by some name which
> may change depending on how it's attached to the system, use the devlabel
> (via /dev/disk/by-label or mount options or whatever), which doesn't change
> regardless of how the disk is attached to the system.

Sure, symlinks based on filesystem metadata are the way to go here.
Usually the fs UUID is used in fstab and such, and works pretty well.

Thanks,
Kay