Option to use /dev values instead of UUID values

[Karl Larsen]

On 03/24/2010 08:09 AM, J wrote:
> 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.
>    
     I use Ubuntu as my home system. I learn about Windows because my 
wife is a user. I have no need for a Server OS.




> 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.
>
>    
     Not if your using it for business!!

> 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.
>    
         I have just one hard drive. No problems if you have just one 
hard drive. I had two hard drives at one time, a IDE and a SATA. My BIOS 
went bonkers! I had to stop using this system because of the problems 
you are showing. The fix has been great.

> 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.
>
>    
     You can build a case for UUID and I have shown with just one hard 
drive, your wasting time with the confusing UUID things.

73 Karl