UUIDs on drives

[Derek Broughton]

ghe wrote:

> | What if the first harddrive on the scsi bus doesn't have the OS on it,
> | and you remove it?
> 
> The installer has told everybody that the drive with the OS is at port
> 0Xnnnn, SCSI id #m. Or PCI slot #n, SATA channel #m. No problem.

The installer told everybody that the filesystem with the OS has
UUID=1234-5678-ABCD-EF01.  Even less problem.

> 
> If you pull the one that *does* have the OS, though, you have to put it
> back :-) Where it was.

That seems retrograde.  It's so much easier to boot from it wherever you
find it.

> | How exactly can you tell the difference between a picture frame, an
> | MP3 player and a USB stick?  They're probably using the same chipset
> | anyways....
> 
> Good point. But they're still plugged into port #0 or #35 or something
> on the USB chip. There's still an order at the hardware level, even
> though it may not mean a lot at the software level.

It can't mean _anything_ unless I always plug my USB devices into the same
slots.

> | Identifying the file system at the file system level uniquely is the
> | only solution I can think of that deals with all this mess of
> | different devices that appear at different times and places.
> 
> Yes. At the software level. But at boot time, the hardware must be
> identifiable uniquely, and repeatably.

You keep saying that, but it's clearly not true.  I should actually be able
to take my boot partition right off a hard drive, dd it to a USB stick
(keeping the old UUID!) and boot off the USB stick.  Highly hazardous - and
still potentially fatal if the old device is still attached - but very
handy.
-- 
derek