UUIDs on drives

[Brian Astill]

On Thursday 14 August 2008 13:48:44 you wrote:

> > If there is a key to unravel the info implicit in /dev/hdb3
> > (Primary partition on the Slave drive) from its UUID, would
> > someone please publish it.
>
> huh?
The "old" system tells what drive and what partition it refers to.  
UUID doesn't.  If it did, I would complain MUCH less.

> create a file system, they all get a fresh new UUID.  
But what if I don't want to?  Say I have a 32-bit version of 
Ubuntu with a separate /home partition.  Assume that after that I 
want to try the 64-bit version on a separate partition without 
risking damage to my /home. so I just install all on the one 
partition.  If the install goes well, I need to change fstab so 
it mounts my home directory, rather than the one it set up by 
default.  How, if UUID is all I have to identify it?

> you can 
> change/create a new UUID with the filesystem utilities if you
> want. (like tune2fs, I believe, for ext3)
But it already has one, which is used  (in the example above) by 
an existing system.

> More bits = less chance accidentally duplicating a UUID from
> random creation.

That is _the_ issue, SFAIAC.   I would not object to a rational ID 
plus a random component, so there would be no duplication.

> I deal
> with system that have several hard drives on multiple
> controllers.. I assure you, this change is not only progress,,
> it's outright necessity.

Your server world is different from my desktop world.  In my world 
the trend is to fewer, but much larger, drives.  In my world we 
often have a "working" drive, and use the other 
for "experimenting" - changing partitions and usage as desire 
dictates.  For us, UUID seems to present an unnessary barrier.

-- 
Regards,
Brian