cvs commit: src/sbin/gpt gpt.c

[Ceri Davies]

On Thu, Apr 24, 2008 at 10:21:20AM +0100, Doug Rabson wrote:
> 
> On 23 Apr 2008, at 21:54, Marcel Moolenaar wrote:
> 
>> 
>> On Apr 23, 2008, at 12:09 PM, John Baldwin wrote:
>> 
>>> On Wednesday 23 April 2008 02:54:40 pm Doug Rabson wrote:
>>>> 
>>>> On 23 Apr 2008, at 19:48, John Baldwin wrote:
>>>> 
>>>>> jhb         2008-04-23 18:48:36 UTC
>>>>> 
>>>>> FreeBSD src repository
>>>>> 
>>>>> Modified files:        (Branch: RELENG_7)
>>>>>  sbin/gpt             gpt.c
>>>>> Log:
>>>>> MFC: Add 'zfs' as an alias for the FreeBSD ZFS UUID.
>>>> 
>>>> Does it make sense to have a FreeBSD ZFS UUID? ZFS is a portable
>>>> filesystem format - shouldn't we use whatever UUID Solaris uses for
>>>> ZFS in GPT?
>>> 
>>> That's a good question.  Maybe pjd@ or marcel@ have opinions on the 
>>> matter?
>> 
>> There's no such UUID as far as I know, so I thought it safer
>> to create a FreeBSD-specific one because we already have
>> incompatibilities between operating systems for things like
>> UFS and BSD labels. While ZFS may be portable, I'm not at all
>> sure that different OSes are feature compatible and for that
>> it's good to know where the ZFS originates from. Also, we may
>> create an UUID with the intend that it's a common UUID, but
>> getting other OSes to use that UUID is far from easy.
> 
> As far as I can make out from the Solaris source, it uses:
> 
> 	6a898cc3-1dd2-11b2-99a6-080020736631 V_USR
> 
> Unfortunately it seems to use this UUID for lots of other things too. I 
> think it sets the partition name to "zfs" for partitions that are part of a 
> ZFS pool.

From libzfs_pool.c:

   2628 	 * Why we use V_USR: V_BACKUP confuses users, and is considered
   2629 	 * disposable by some EFI utilities (since EFI doesn't have a backup
   2630 	 * slice).  V_UNASSIGNED is supposed to be used only for zero size
   2631 	 * partitions, and efi_write() will fail if we use it.  V_ROOT, V_BOOT,
   2632 	 * etc. were all pretty specific.  V_USR is as close to reality as we
   2633 	 * can get, in the absence of V_OTHER.

To Solaris administrators, the majority of the V_ p_tag values are
considered exactly equivalent, since the format(1M) command allows you
to set them to anything when an SMI label is used.

Ceri
-- 
That must be wonderful!  I don't understand it at all.
                                                  -- Moliere
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