From mboxrd@z Thu Jan  1 00:00:00 1970
From: Matthew Dharm <mdharm-usb@one-eyed-alien.net>
Date: Thu, 03 Jul 2008 15:33:36 +0000
Subject: Re: not all volume types export UUIDs (was: /dev/disk/by-id symlinks should not include bus) type
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References: <20080702102820.GB16076@piper.oerlikon.madduck.net>
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To: linux-hotplug@vger.kernel.org


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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 +02=
00]:
> > > > > All are only unique per namespace/bus, and should better not be
> > > > > mixed.
> > > >=20
> > > > 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?
> > > >=20
> > > > 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.
> > >=20
> > > So, what id's/symlinks is the same disk showing for ATA and USB in yo=
ur
> > > case?
> > >=20
> > > Only advanced USB bridges read the number from the actual disk, I hav=
e 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.
> >=20
> > Isn't devlabel the technology that is supposed to be used for this sort=
 of
> > scenario?
>=20
> 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.

Matt

--=20
Matthew Dharm                              Home: mdharm-usb@one-eyed-alien.=
net=20
Maintainer, Linux USB Mass Storage Driver

Type "format c:"  That should fix everything.
					-- Greg
User Friendly, 12/18/1997

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