Re: [linux-lvm] Any way to speed up activation of volumes with snapshots?

[Zdenek Kabelac <zkabelac@redhat.com>]

Dne 16.9.2015 v 17:30 Chris Friesen napsal(a):
> On 09/16/2015 02:27 AM, Zdenek Kabelac wrote:
>> Dne 16.9.2015 v 01:03 Chris Friesen napsal(a):
>
>>> As a side question, currently we have a script which runs "vgchange -ay <vg>",
>>> which will activate the VG.
>>>
>>> This script appears to activate the LVs within the VG serially rather than in
>>> parallel.  Does it do any processing to determine in which order to activate
>>> the LVs?
>
>> What you can do with recent versions of lvm2 -  you could 'mark' (with lvchange
>> --setskipactivation) some LVs to be skipped from normal activation.
>> Then you could activate such skipped LVs with  'lvchange -ay -K'.
>>
>> As said lvm2 has not been designed for this case.
>> (btw during whole activation - your access to VG is actually limited only for
>> 'read-only')
>
> Right...we're planning on testing out thin provisioning but I have to figure
> out a band-aid solution for products already in use.
>
> Just to clarify...what does your "access to VG is actually limited only for
> 'read-only'" mean exactly?
>
> Does it mean:
>
> 1) I only have read-only access to the LVs within the VG until all LVs in the
> VG are activated?
>
> or
>
> 2) I only have readonly access to the VG (so I can't add/remove/modify LVs)
> but I have read/write access to the LVs within the VG.

2. is correct - you will not be able to modify VG content (as read-lock is 
held for VG - and you need write-lock for updates)

Zdenek