Re: Query about command line commands

[Bret Busby]

On 10/03/2015, Simon Hobson <address@hidden> wrote:
> Bret Busby <address@hidden> wrote:
>
>> Plurry UUID - those things should be banned, and devices, eg
>> "/dev/sda<x>/", or, as in PC-BSD output below, "ada<y>p<x>" should be
>> used, to make it all less obscurantist and more user-friendly - "the
>> way it used to be".
>
> They were introduced to fix a very real problem - and one that I've been hit
> with.
> If you only have one disk then you're not affected. If you have multiple
> disks but on one controller, then you *probably* are not affected. If you
> have disks on multiple controllers/controller types then you are affected.
>
> It's to do with the indeterminate way that controllers may be located and
> drivers loaded. There's no way to guarantee that what appears to the OS as
> sda *on this boot* will be sda to the bootloader - or even to the same OS on
> the next boot.
>
> Personally I prefer to use filesystem labels - Debian doesn't support that
> in it's packaging of Grub, though it does support using device names (eg
> sda). It will do what using UUID does - but it does need admin intervention
> to set the labels *AND* the admin has to make sure the labels are unique.
> That includes allowing for (say) calling your root filesystem "root" and
> then connecting an external drive which also has a filesystem called
> "root".
>
> So while they are a bit of a PITA when you have to copy and type them, they
> are there for a good reason.
>

Okay, well, we are each entitled to our own opinions. Mine may be not
a good opinion, in the wider world of bigger and more complicated
systems, but, it is my opinion, based on my experience.

In the context of this problem, GRUB did not recognise the UUID, as
shown in the message to which you were responding.

As it happened, I could not use the GRUB CLI, to restore the GRUB
bootloader, but, upon advice from the Debian User list, I used a
Ubuntu server image, via its Rescue Mode, to restore the system to its
previous usable state, whence I can now boot into Ubuntu 14.04
Desktop, or Debian 7, and I have successfully, booted into, and,
updated, each of those two operating systems..

So, the system is once again, usable.

-- 
Bret Busby
Armadale
West Australia
..............

"So once you do know what the question actually is,
 you'll know what the answer means."
- Deep Thought,
 Chapter 28 of Book 1 of
 "The Hitchhiker's Guide to the Galaxy:
 A Trilogy In Four Parts",
 written by Douglas Adams,
 published by Pan Books, 1992

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