[Pacemaker] Migration of "lower" resource causes dependent resources to restart

[Vladislav Bogdanov]

29.03.2012 09:43, Vladislav Bogdanov wrote:
> 29.03.2012 09:35, Andrew Beekhof wrote:
>> On Thu, Mar 29, 2012 at 5:28 PM, Vladislav Bogdanov
>> <bubble at hoster-ok.com> wrote:
>>> Hi Andrew, all,
>>>
>>> Pacemaker restarts resources when resource they depend on (ordering
>>> only, no colocation) is migrated.
>>>
>>> I mean that when I do crm resource migrate lustre, I get
>>>
>>> LogActions: Migrate lustre#011(Started lustre03-left -> lustre04-left)
>>> LogActions: Restart mgs#011(Started lustre01-left)
>>>
>>> I only have one ordering constraint for these two resources:
>>>
>>> order mgs-after-lustre inf: lustre:start mgs:start
>>>
>>> This reminds me what have been with reload in a past (dependent resource
>>> restart when "lower" resource is reloaded).
>>>
>>> Shouldn't this be changed? Migration usually means that service is not
>>> interrupted...
>>
>> Is that strictly true?  Always?
> 
> This probably depends on implementation.
> With qemu live migration - yes.
> With pacemaker:Dummy (with meta allow-migrate="true") probably yes too...
> 

And if RA is just a management for some external entity - then yes too
(although this case is probably not very common ;) ).

>> My understanding was although A thinks the migration happens
>> instantaneously, it is in fact more likely to be pause+migrate+resume
>> and during that time anyone trying to talk to A during that time is
>> going to be disappointed.