[dm-devel] Reducing size of thin spare metadata, thin metadata

[Patrik Horník]

Thanks Zdenku. But you did not answer some of my questions, which I
need to know to decide... So is there a way I can create smaller spare
metadata LV? In mentioned manual steps what do I need mytemplv for and
why cant I use original pool metadata as input of thin_repair?

Thanks.

2014-10-06 10:31 GMT+02:00 Zdenek Kabelac <zkabelac at redhat.com>:
> Dne 6.10.2014 v 10:12 Patrik Horník napsal(a):
>>
>> OK, I see. So the result is that pool is not activated when it does
>> not pass check and there is no spare? So is it totally safe to have no
>> spare?
>>
>> And so is there a way to reduce size of spare / create spare of
>> specified (smaller) size after its removal?
>>
>
> Idea behind spare is to have 'reserved' space for pool metadata recovery.
> (it's like hidden space in filesystem)
>
> When the pool gets broken and you don't have reserved space for repair
> you need to add new free space for recovery.
>
> And at this moment it's getting quite complex (well beyond autonomous
> 'lvconvert --repair').
>
> So as long as you know what you are doing and you could repair
> metadata manually - you are fine.
> (You could disable creation of spare volume in lvm.conf)
>
> But lvm2 requires to have reserved space to proceed for --repair.
> After all - the size of pool metadata should be pretty small compared with
> the rest of VG.
>
> Zdenek
>