[ClusterLabs] R: Re: Antw: Re: Ordering Sets of Resources

[Ken Gaillot]

On 03/01/2017 03:22 PM, ivagal at libero.it wrote:
> You are right, but i had to use option symmetrical=false because i need to 
> stop, when all resources are running, even the single primitive with no impact 
> to others resources.
> 
> I have also used symmetrical=false with kind=Optional.
> The stop of the individual resource does not stop the others resources, but if 
> during the startup or shutdown of the resources is used a list of primitives 
> without any order, the resources will start or stop without respecting the 
> constraint strictly.
> 
> Regards
> Ivan

If I understand, you want to be able to specify resources A B C such
that they always start in that order, but stopping can be in any
combination:
* just A
* just B
* just C
* just A and B (in which case B stops then A)
* just A and C (in which case C stops then A)
* just B and C (in which case C stops then B)
* or all (in which case C stops, then B, then A)

There may be a fancy way to do it with sets, but my first thought is:

* Keep the start constraint you have

* Use individual ordering constraints between each resource pair with
kind=Optional and action=stop

>> ----Messaggio originale----
>> Da: "Ken Gaillot" <kgaillot at redhat.com>
>> Data: 01/03/2017 15.57
>> A: "Ulrich Windl"<Ulrich.Windl at rz.uni-regensburg.de>, <users at clusterlabs.org>
>> Ogg: Re: [ClusterLabs] Antw: Re:  Ordering Sets of Resources
>>
>> On 03/01/2017 01:36 AM, Ulrich Windl wrote:
>>>>>> Ken Gaillot <kgaillot at redhat.com> schrieb am 26.02.2017 um 20:04 in 
> Nachricht
>>> <dbf562ff-a830-fc3c-84dc-487b892fcba4 at redhat.com>:
>>>> On 02/25/2017 03:35 PM, ivagal at libero.it wrote:
>>>>> Hi all,
>>>>> i have configured a two node cluster on redhat 7.
>>>>>
>>>>> Because I need to manage resources stopping and starting singularly when
>>>>> they are running I have configured cluster using order set constraints.
>>>>>
>>>>> Here the example
>>>>>
>>>>> Ordering Constraints:
>>>>>   Resource Sets:
>>>>>     set MYIP_1 MYIP_2 MYFTP MYIP_5 action=start sequential=false
>>>>> require-all=true set MYIP_3 MYIP_4 MYSMTP action=start sequential=true
>>>>> require-all=true setoptions symmetrical=false
>>>>>     set MYSMTP MYIP_4 MYIP_3 action=stop sequential=true
>>>>> require-all=true set MYIP_5 MYFTP MYIP_2 MYIP_1 action=stop
>>>>> sequential=true require-all=true setoptions symmetrical=false 
> kind=Mandatory
>>>>>
>>>>> The constrait work as expected on start but when stopping the resource
>>>>> don't respect the order.
>>>>> Any help is appreciated
>>>>>
>>>>> Thank and regards
>>>>> Ivan
>>>>
>>>> symmetrical=false means the order only applies for starting
>>>
>>> From the name (symmetrical) alone it could also mean that it only applies 
> for stopping ;-)
>>> (Another example where better names would be nice)
>>
>> Well, more specifically, it only applies to the action specified in the
>> constraint. I hadn't noticed before that the second constraint here has
>> action=stop, so yes, that one would only apply for stopping.
>>
>> In the above example, the two constraints are identical to a single
>> constraint with symmetrical=true, since the second constraint is just
>> the reverse of the first.