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

[Vadym Chepkov]

On Jun 15, 2010, at 7:50 AM, Andrew Beekhof wrote:

> 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?

what about this part? what do I need to do to prevent them from running on different nodes for sure?


>> 
>> 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.

My guess is for two resources it's
colocation onlyone -inf: _rsc_set_ dummy1 dummy2

and a patch. Would you include it in 1.0.9, by any chance? 

Thank you,
Vadym