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

[Andrew Beekhof]

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?
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.