Re: BTRFS messes up snapshot LV with origin

[Goffredo Baroncelli <kreijack@inwind.it>]

On 11/29/2014 02:25 AM, Robert White wrote:
> On 11/28/2014 09:05 AM, Goffredo Baroncelli wrote:
>> For the disk autodetection, I still convinced that it is a "sane"
>> default to skip the lvm-snapshot
> 
> No... please don't...
> 
> Maybe offer an option to select between snapshots or no-snapshots but
> in much the same way there is no _functional_ difference between a
> subvolume and a snapshot in btrfs, there is no "degenerate" status to
> an LVM snapshot.

I agree with you; but I have to find a "default" so during the boot
a system can start even if snapshots are present.

And pay attention that there would be cases where multiple
snapshot are present: how group these ? My be for generation number ?

Anyway for the moment my help simply refuse to mount if there is
a conflict of dev_uuid.

> 
> It would be way more useful if the helper dumped a message via stderr
> or syslog that said something like "UUID=xxxxxxxx ambiguous, 

This is what it is printed when the helper finds a duplicate uuid:

ghigo@emulato:~$ sudo lvdisplay | grep "LV Path"
  LV Path                /dev/test/lv01
  LV Path                /dev/test/lv02
  LV Path                /dev/test/lv02_snap
  LV Path                /dev/test/lv01_snap

ghigo@emulato:~$ sudo mount /dev/test/lv01 /mnt/btrfs1/
ERROR: disk '/dev/mapper/test-lv01' and '/dev/mapper/test-lv01_snap' have the same disk uuid
ERROR: disk '/dev/mapper/test-lv02_snap' and '/dev/mapper/test-lv02' have the same disk uuid

> must
> select between /dev/AA and /dev/BB using device= to mount
> filesystem."

But anyway I can force the disk to mount:

ghigo@emulato:~$ sudo mount /dev/test/lv01_snap -o device=/dev/test/lv02_snap /mnt/btrfs1/

> 
> 
> 


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