[ClusterLabs] [Question] About a change of crm_failcount.

[Ken Gaillot]

On 02/02/2017 12:33 PM, Ken Gaillot wrote:
> On 02/02/2017 12:23 PM, renayama19661014 at ybb.ne.jp wrote:
>> Hi All,
>>
>> By the next correction, the user was not able to set a value except zero in crm_failcount.
>>
>>  - [Fix: tools: implement crm_failcount command-line options correctly]
>>    - https://github.com/ClusterLabs/pacemaker/commit/95db10602e8f646eefed335414e40a994498cafd#diff-6e58482648938fd488a920b9902daac4
>>
>> However, pgsql RA sets INFINITY in a script.
>>
>> ```
>> (snip)
>>     CRM_FAILCOUNT="${HA_SBIN_DIR}/crm_failcount"
>> (snip)
>>     ocf_exit_reason "My data is newer than new master's one. New   master's location : $master_baseline"
>>     exec_with_retry 0 $CRM_FAILCOUNT -r $OCF_RESOURCE_INSTANCE -U $NODENAME -v INFINITY
>>     return $OCF_ERR_GENERIC
>> (snip)
>> ```
>>
>> There seems to be the influence only in pgsql somehow or other.
>>
>> Can you revise it to set a value except zero in crm_failcount?
>> We make modifications to use crm_attribute in pgsql RA if we cannot revise it.
>>
>> Best Regards,
>> Hideo Yamauchi.
> 
> Hmm, I didn't realize that was used. I changed it because it's not a
> good idea to set fail-count without also changing last-failure and
> having a failed op in the LRM history. I'll have to think about what the
> best alternative is.

Having a resource agent modify its own fail count is not a good idea,
and could lead to unpredictable behavior. I didn't realize the pgsql
agent did that.

I don't want to re-enable the functionality, because I don't want to
encourage more agents doing this.

There are two alternatives the pgsql agent can choose from:

1. Return a "hard" error such as OCF_ERR_ARGS or OCF_ERR_PERM. When
Pacemaker gets one of these errors from an agent, it will ban the
resource from that node (until the failure is cleared).

2. Use crm_resource --ban instead. This would ban the resource from that
node until the user removes the ban with crm_resource --clear (or by
deleting the ban consraint from the configuration).

I'd recommend #1 since it does not require any pacemaker-specific tools.

We can make sure resource-agents has a fix for this before we release a
new version of Pacemaker. We'll have to publicize as much as possible to
pgsql users that they should upgrade resource-agents before or at the
same time as pacemaker. I see the alternative PAF agent has the same
usage, so it will need to be updated, too.