[Pacemaker] crm shell and collocating sets

[Vadym Chepkov]

On Mon, Jan 24, 2011 at 10:41 AM, Dejan Muhamedagic <dejanmm at fastmail.fm> wrote:
> Hi,
>
> On Sat, Jan 22, 2011 at 01:38:12PM -0500, Vadym Chepkov wrote:
>> Hi,
>>
>> It seems crm shell can't express sequential="true" in  collocating sets, which is strange, since, I assume, it's a default.
>>
>> If you load an example using cibadmin from "Configuration explained"
>>
>> Example 6.16. Using colocation sets to specify a common peer.
>>   <constraints>
>>     <rsc_colocation id="coloc-1" score="INFINITY" >
>>       <resource_set id="collocated-set-1" sequential="false">
>>         <resource_ref id="A"/>
>>         <resource_ref id="B"/>
>>         <resource_ref id="C"/>
>>       </resource_set>
>>       <resource_set id="collocated-set-2" sequential="true">
>>         <resource_ref id="D"/>
>>       </resource_set>
>>     </rsc_colocation>
>>   </constraints>
>>
>>
>> It will look like this in crm configure show output:
>>
>> xml <rsc_colocation id="coloc-1" score="INFINITY"> \
>>       <resource_set id="collocated-set-1" sequential="false"> \
>>               <resource_ref id="A"/> \
>>               <resource_ref id="B"/> \
>>               <resource_ref id="C"/> \
>>       </resource_set> \
>>       <resource_set id="collocated-set-2" sequential="true"> \
>>               <resource_ref id="D"/> \
>>       </resource_set> \
>> </rsc_colocation>
>>
>> Not exactly a "simplification"
>>
>> Am I missing something? How one would express the same constraint using shell?
>
> By omitting sequential="true". The problem is that two XML
> representation have the same meaning, but look slightly
> different, which again makes shell think that it could've done
> something wrong while rendering XML from the CLI presentation.
>
> Anyway, that should be fixed somehow.
>
> Thanks,
>
> Dejan

If you ever consider do something about it, here is another thing that
can be lived with, but is non-intuitive.

1) colocation c1 inf: A B

the most significant is B (if B is stopped nothing else will be running)

2) colocation c2 inf: A B C

most significant - A

3) colocation c3 inf: ( A B ) C

most significant - C

4) colocation c4 inf: ( A B ) C D

most significant - C again

I am trying to find a logic to remember this, but fails so far :)

Thanks,
Vadym