[Pacemaker] RFC: What part of the XML configuration do you hate the most?

Satomi TANIGUCHI taniguchis at intellilink.co.jp
Wed Sep 24 04:34:37 EDT 2008


Now I'm posting the patch which is to implement on_fail="standby".
This patch is for pacemaker-dev(5383f371494e).

Its purpose is to move all resources away from the node
when a resource is failed on that.
This setting is for start or monitor operation, not for stop op.
And as far as I confirm, the loop which Andrew said doesn't appear.

Your comments and suggestions are really appreciated.

Best Regards,

Satomi Taniguchi wrote:
> Hi Andrew,
> Andrew Beekhof wrote:
>  >
> (snip)
>  >
>  > no, i'm indicating that you've underestimated the scope of the problem
>  >
> (snip)
> Bugzilla #1601 is caused by moving healthy resource in STONITH ordering, 
> isn't it?
> I changed nothing about STONITH action when I implemented 
> on_fail="standby".
> On the failure of stop operation or when Sprit-Brain occurs,
> I completely agree with that on_fail should be "fence".
> But I consider about start or monitor operation's failure.
> And on_fail="standby" is on the assumption that it is used only for 
> these operations.
> Its purpose is not to move healthy resources before doing STONITH,
> but to move all resources away from the node which a resouce is failed.
> And in any operation, Bugzilla#1601 doesn't occur because I changed 
> nothing about STONITH.
> STONITH doesn't require to stop any resources.
> The following is why I make much of start and monitor operations.
> What I regard seriously are:
>   - 1)On a resource's failure, only the failed resource
>       and resources which are in the same group move from
>       the failed node.
>       -> At present, to move all resources (even if they are not
>          in the group or have no constraints) away from
>          the failed node automatically, on_fail setting of
>          not only stop but start and monitor has to be set
>          "fence" and the failure node has to be killed by STONITH.
>   - 2)(In connection with 1) When resources are moved away by failure
>       of start or monitor operation, they should be shutdown normally.
>       -> It sounds extremely normal, but it is impossible
>          if you accord with 1).
>       -> Of course, I know that I have to kill the failed node
>          immediately if stop operation's failure or Split-Brain occurs.
>   - 3)Rebooting the failed node may lose the evidence of
>       the real cause of a failure
>       (nearly equal administrators can't analyse the failure).
>       -> This is as Keisuke-san wrote before.
>          It is a really serious matter in Enterprise services.
> To solve the matters above, I implemented on_fail="standby".
> If you have any other ideas to solve them, please let me know.
> Just for reference, there is an example in attached files:
> a resource group named "grpPostgreSQLDB" consists of 
> IPaddr("prmIpPostgreSQLDB") and pgsql("prmApPostgreSQLDB") is working on 
> node2.
> (See: crm_mon_before.log)
> I modified pgsql's stop function to always return $OCF_ERR_GENERIC.
> When IPaddr resource failed, and its monitor's on_fail is "standby", 
> pgsql tried to stop but it failed.
> (See: pe-warn-0.node2.gif)
> Then STONITH was executed according to the setting of pgsql's stop 
> operation, on_fail="fence".
> (See: pe-warn-1.node2.gif and pe-warn-0.node1.gif)
> STONITH killed node2 pitilessly, and both resources of the group moved 
> to node1 peacefully.
> (See: crm_mon_after.log)
> Best Regards,
> Satomi Taniguchi
> Andrew Beekhof wrote:
>> On Aug 4, 2008, at 8:11 AM, Satomi Taniguchi wrote:
>>> Hi Andrew,
>>> Thank you for your opitions!
>>> But I'm afraid that you've misunderstood my intentions...
>> no, i'm indicating that you've underestimated the scope of the problem
>>> Andrew Beekhof wrote:
>>> (snip)
>>>> Two problems...
>>>> The first is that standby happens after the fencing event, so it's 
>>>> not really doing anything to migrate the healthy resources.
>>> In the graph, the object "stonith-1 stop 0 rh5node1" just means
>>> "a plugin named stonith-1 on rh5node1 stops",
>>> not "fencing event occurs".
>>> For example, Node1 has two resource groups.
>>> When a resource in one group is failed,
>>> all resources in both groups stopped completely,
>>> and stonith plugin on Node1 stopped.
>>> After this, both resource group work on Node2.
>>> I attacched a graph, cib.xml
>>> and crm_mon's logs (before and after a resource broke down).
>>> Please see them.
>>>> Stop RscZ -(depends on)-> Stop RscY  -(depends on)-> Stonith NodeX  
>>>> -(depends on)-> Stop RscZ  -(depends on)-> ...
>>> I just want to stop all resources without STONITH when monitor NG,
>>> I don't want to change any actions when stop NG.
>>> The setting on_fail="standby" is for start or monitor operation, and
>>> it is on condition that the setting of stop operation's on_fail is 
>>> "fence".
>>> Then, STONITH is not executed when start or monitor is failed,
>>> but it is executed when stop is failed.
>>> So, if RscY's monitor operation is failed,
>>> its stop operation doesn't depend on "Sonith NodeX".
>>> And if it is failed to stop RscY,
>>> NodeX is turned off by STONITH, and the loop above does not occur.
>>> Best Regards,
>>> Satomi Taniguchi
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