Option to use /dev values instead of UUID values

[J]

On Mon, Mar 15, 2010 at 16:23, Karl Larsen <klarsen1 at gmail.com> wrote:
>
>         Yes! Whoever invented the UUID should be ashamed! I realize
> that the UUID is supposed to correct when you remove a partition but who
> does this ever or at all? As for using the simple /dev/sda3 like, I do
> that for all the things I put in fstab.

I wonder if you guys are thinking about this from a broad perspective.
 On a desktop or Laptop, it may or may not make sense to use UUIDs
since disks never change and you usually only use what's inside the
box.  On servers (and like it or not, Linux is, first and foremost, a
Server OS) that is not necessarily true.

On a server, you could have any combination of internal and external
block devices.  A mix of SAS and SATA and external SAS and SATA and
SCSI and hardware RAID and Fibrechannel and iSCSI, all in the same
box.

the /dev/ devices (/dev/sda, /dev/sdb, etc) are assigned at boot time
and are entirely dependent on what order the modules load.  Believe
me, I've had plenty of headaches because a given system would not
boot.  The installer said it installed to /dev/sda.  However, after
installing and re-booting, /dev/sda had become /dev/sdd because three
FC devices were loaded before the onboard drive.

It happens.  /dev disk devices are NOT immutable, unlike UUID.  They
can be very fluid (as is anything that's generated and assigned at
boot) and that can cause problems.

Is it likely you'll see these problems on your desktop or laptop?  Not
necessarily.  But consider this... your motherboard has two SATA plugs
and you have two SATA drives pluged in, which always show up as
/dev/sda and /dev/sdb.  But you want more drives, so you get a SATA
PCIe card and install that along with two more drives.  But the module
for that card loads first, OR, it uses the same module as your
onboard, BUT, the drives on the PCIe card are presented to the OS
first.  So now, your two new drives become sda and sdb, while your old
ones become sdc and sdd.

BIOS still hits your original onboard HDD and pulls grub, but once
grub starts looking for /dev/sda, it finds a /dev/sda that has no
/boot partition (because your boot partition is now on /dev/sde).

THAT kind of mess is why UUIDs are used.  Disk labels can be used like
this as well, but they have other drawbacks.