[Pacemaker] Shouldn't colocation -inf: be mandatory?

[Andrew Beekhof]

On Tue, Jun 15, 2010 at 1:38 PM, Vadym Chepkov <vchepkov at gmail.com> wrote:
>
> On Jun 15, 2010, at 4:57 AM, Andrew Beekhof wrote:
>
>> On Tue, Jun 15, 2010 at 10:23 AM, Andreas Kurz <andreas.kurz at linbit.com> wrote:
>>> On Tuesday 15 June 2010 08:40:58 Andrew Beekhof wrote:
>>>> On Mon, Jun 14, 2010 at 4:22 PM, Vadym Chepkov <vchepkov at gmail.com> wrote:
>>>>> On Jun 7, 2010, at 8:04 AM, Vadym Chepkov wrote:
>>>>>> I filed bug 2435, glad to hear "it's not me"
>>>>>
>>>>> Andrew closed this bug
>>>>> (http://developerbugs.linux-foundation.org/show_bug.cgi?id=2435) as
>>>>> resolved, but I respectfully disagree.
>>>>>
>>>>> I will try to explain a problem again in this list.
>>>>>
>>>>> lets assume you want to have several resources running on the same node.
>>>>> They are independent, so if one is going down, others shouldn't be
>>>>> stopped. You would do this by using a resource set, like this:
>>>>>
>>>>> primitive dummy1 ocf:pacemaker:Dummy
>>>>> primitive dummy2 ocf:pacemaker:Dummy
>>>>> primitive dummy3 ocf:pacemaker:Dummy
>>>>> colocation together inf: ( dummy1 dummy2 dummy3 )
>>>>>
>>>>> and I expect them to run on the same host, but they are not and I
>>>>> attached hb_report to the case to prove it.
>>>>>
>>>>> Andrew closed it with the comment "Thats because you have
>>>>> sequential="false" for the colocation set." But sequential="false" means
>>>>> doesn't matter what order do they start.
>>>>
>>>> No.  Thats not what it means.
>>>> And I believe I should know.
>>>>
>>>> It means that the members of the set are NOT collocated with each
>>>> other, only with any preceding set.
>>>
>>> Just for clarification:
>>>
>>> colocation together inf: ( dummy1 dummy2 dummy3 ) dummy4
>>>
>>> .... is a shortcut for:
>>>
>>> colocation together1 inf: dummy4 dummy1
>>> colocation together1 inf: dummy4 dummy2
>>> colocation together1 inf: dummy4 dummy3
>>>
>>> ... is that correct?
>>
>> Only if sequential != false.
>> For some reason the shell appears to be setting that by default.
>>
>>>
>>> To pick up Vadym's Question:
>>>
>>> *  what would be the correct syntax to say "run-together-but-dont-care-if-one-
>>> dies-or-is-not-runable"?
>>
>> Choose a score < inf, just like regular colocation constraints.
>
> Ah, ok, thanks, I guess in my mind anything less then inf was "advisory".

They are.

Advisory is the only way to deal with the
"but-dont-care-if-one-dies-or-is-not-runable" part.

> As long as I keep it above any resource-stickiness it should be in fact mandatory, right?
> Or something else needs to be taken to consideration?
>
> On a side note, I was trying to figure out how to make a set from two resources, so I just added a proper xml and checked what crm shell say about it. And it shows it like this:
>
> colocation together 5000: _rsc_set_ dummy1 dummy2

Strange.  Dejan?

>
> Who knew? I didn't see it anywhere in documentation.
>
> Anyway, just so I get it right, what would be the opposite constraint (which is what this thread started from)
> If I want to have same dummy1, dummy2, dummy3 resources, but I don't want any of them ever to run simultaneously on the same host. What wold be the proper anti-colocation constraint for this configuration?

Score = -inf, plus the patch, plus sequential = true (or unset).
Not sure how that looks in shell syntax though.