[Pacemaker] Re: Understanding rules: location, colocation, order. Using with Master/Slave

[Serge Dubrouski]

Something like this:

      <rsc_order id="drbd0_before_myGroup" first="ms-drbd0"
then="myGroup" then-action="start" first-action="promote"/>
      <rsc_colocation id="myGroup_on_drbd0" rsc="myGroup"
with-rsc="ms-drbd0" with-rsc-role="Master" score="INFINITY"/>
      <rsc_location id="primNode" rsc="myGroup">
        <rule id="prefered_primNode" score="1000">
          <expression attribute="#uname" id="expression.id2242728"
operation="eq" value="fc-node1"/>
        </rule>
      </rsc_location>

See that cib.xml that I sent you a couple of days ago. First rule will
promote DRBD before starting a group, second will collocate master and
a group, third one will place group and master to the desired node.


On Mon, Oct 27, 2008 at 12:24 PM, Adrian Chapela
<achapela.rexistros at gmail.com> wrote:
> Serge Dubrouski escribió:
>>
>> On Mon, Oct 27, 2008 at 12:07 PM, Adrian Chapela
>> <achapela.rexistros at gmail.com> wrote:
>>
>>>>
>>>> Hello!
>>>>
>>>> I am working on a cluster with a two Master/Slave instances.
>>>>
>>>> I have: 2 drbd Master/Slave instance, 1 pingd clone instance, 1 group
>>>> with
>>>> Filesystem resource.
>>>>
>>>> ms-drbd0 is the first Master/Slave
>>>> ms-drbd1 is the second Master/Slave
>>>> mail_Group is the first group, it depends on ms-drbd0
>>>> samba_Group is the second group, it depends on ms-drbd1
>>>>
>>>> I have the next rules:
>>>>
>>>> <rsc_order id="mail-drbd0_before_fs0" from="Montaxe_mail" action="start"
>>>> to="ms-drbd0" to_action="promote"/>
>>>> <rsc_order id="samba-drbd1_before_fs0" from="Montaxe_samba"
>>>> action="start"
>>>> to="ms-drbd1" to_action="promote"/>
>>>> (starts Montaxe_mail when ms-drbd0 has been promoted, start
>>>> Montaxe_samba
>>>> when ms-drbd1 has been promoted. These rules are ok, I think)
>>>>
>>>> <rsc_colocation id="mail_Group_on_ms-drbd0" to="ms-drbd0"
>>>> to_role="master"
>>>> from="mail_Group" score="INFINITY"/>
>>>> <rsc_colocation id="samba_Group_on_ms-drbd1" to="ms-drbd1"
>>>> to_role="master" from="samba_Group" score="INFINITY"/>
>>>> (Run mail_Group only on the master node, run samba_Group on the master
>>>> node)
>>>>
>>>> <rsc_location id="mail:drbd" rsc="ms-drbd0">
>>>> <rule id="rule:ms-drbd0" role="master" score="100">
>>>>   <expression  attribute="#uname" operation="eq" value="debianquagga2"/>
>>>> </rule>
>>>> <rule id="mail_Group:pingd:rule" score="-INFINITY" boolean_op="or">
>>>>    <expression id="mail_Group:pingd:expr:undefined" attribute="pingd"
>>>> operation="not_defined"/>
>>>>    <expression id="mail_Group:pingd:expr:zero" attribute="pingd"
>>>> operation="lte" value="0"/>
>>>> </rule>
>>>> </rsc_location>
>>>> <rsc_location id="samba:drbd" rsc="ms-drbd1">
>>>> <rule id="rule:ms-drbd1" role="master" score="100">
>>>>   <expression  attribute="#uname" operation="eq" value="debianquagga2"/>
>>>> </rule>
>>>> <rule id="samba_Group:pingd:rule" score="-INFINITY" boolean_op="or">
>>>>    <expression id="samba_Group:pingd:expr:undefined" attribute="pingd"
>>>> operation="not_defined"/>
>>>>    <expression id="samba_Group:pingd:expr:zero" attribute="pingd"
>>>> operation="lte" value="0"/>
>>>> </rule>
>>>> </rsc_location>
>>>> (Select debianquagga2 as Master and if the node lost its connection take
>>>> the score -INFINITY to do failover, it applies to ms-drbd0 and ms-drbd1)
>>>>
>>>> With this rules all is working very well but the node selected as master
>>>> isn't "debianquagga2",   Why could be the reason ?
>>>>
>>>> I using Heartbeat 2.1.4
>>>>
>>>>
>>>
>>> I have attached the cib xml file. If I delete two groups, Master is
>>> debianQuagga2, If not, Master is debianQuagga1.
>>>
>>
>> That probably has something to do with how scores are counted for
>> groups. In your rsc_location rule for masters you have a really low
>> score for assigning master role to debianquagga2. It's possible that
>> groups outscore them with default values. I'm not sure in that, that's
>> just mu guess. You probably can check this with show score scripts.
>>
>
> I will check that, thank you!
>>
>> I'd try to assign rsc_location rules to groups, not to master role.
>> Your collocation rule will control that groups are on the same nodes
>> with the masters. Or you can try to increase your scores from 100 to
>> something higher.
>>
>
> Ok, but I need that node be a master before than start group because it
> depends on the master / slave resource, is that possible changing
> collocation ? Could you open my eyes with a simple example ?
>
>>
>>>
>>> _______________________________________________
>>> Pacemaker mailing list
>>> Pacemaker at clusterlabs.org
>>> http://list.clusterlabs.org/mailman/listinfo/pacemaker
>>>
>>>
>>>
>>
>>
>>
>>
>
>
> _______________________________________________
> Pacemaker mailing list
> Pacemaker at clusterlabs.org
> http://list.clusterlabs.org/mailman/listinfo/pacemaker
>



-- 
Serge Dubrouski.