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

[Vadym Chepkov]

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".
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

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? 

Thanks,
Vadym