Re: [PATCH] mkfs.btrfs: allow UUID specification at mkfs time

[David Pottage <david@chrestomanci.org>]

On 14/05/14 08:31, Wang Shilong wrote:
> On 05/14/2014 09:18 AM, Eric Sandeen wrote:
>> Allow the specification of the filesystem UUID at mkfs time.
>>
>> (Implemented only for mkfs.btrfs, not btrfs-convert).
> Just out of curiosity, this option is used for what kind of use case?
> I notice Ext4 also has this option.:-)
I have used it a few times when replacing the hard disc of a Linux 
system, while trying to leave everything else untouched.

Many distros, including Debian and Ubuntu write the /etc/fstab to 
specify volumes by UUID instead of by label or device path.

I have also had the misfortune to use an embedded system where the boot 
volume UUID was configured into the flash in a non obvious way, so the 
easiest fix was to set-up the boot and root volumes on the replacement 
hard disc to have the same UUID.

Of course in either case I could have just taken a bit for bit copy of 
the source volume using dd, but that had it'd own problems because the 
destination was smaller. I also wanted to defrag the fs while copying it.

-- 
David Pottage