[Pacemaker] How to put delay in fence_intelmodular for one node only
Andrew Beekhof
andrew at beekhof.net
Fri Jun 27 07:40:26 CEST 2014
On 26 Jun 2014, at 8:18 am, Gianluca Cecchi <gianluca.cecchi at gmail.com> wrote:
>
> On Sun, Jun 22, 2014 at 1:51 AM, Digimer <lists at alteeve.ca> wrote:
> Excellent.
>
> Please note; With IPMI-only fencing, you may find that killing all power to the node will cause fencing to fail, as the IPMI's BMC will lose power as well (unless it has it's own battery, but most don't).
>
> If you find this, then the solution I would recommend is to get a pair of switched PDUs (I like the APC brand AP7900, very fast and the fence_apc_snmp agent is very well tested). With this, you can then setup STONITH levels;
>
> http://clusterlabs.org/wiki/STONITH_Levels
>
> With this, if the IPMI fails, Pacemaker will move on and try fencing by cutting power to the lost node, providing a backup method of fencing. If you use stacked switches, put the PDUs on one switch and the IPMI interface on the other switch, and you will provide reliable fencing in a failed-switch state, too.
>
> Cheers!
>
>
> Good points. At the moment this is a lab environment so it is not crucial, but I'll take in mind for production use.
>
> One point: after doing some tests and creating failures of nodes for test I see this behaviour about the special fencing resource
>
> normal behaviour
> [root at srvmgmt02 ~]# crm_mon -1
> ...
> [snip]
> fence_srvmgmt01 (stonith:fence_intelmodular): Started srvmgmt01.localdomain.local
> fence_srvmgmt02 (stonith:fence_intelmodular): Started srvmgmt02.localdomain.local
>
> after fencing of srvmgmt01 (because of drbd problem deliberately produced by me on it)
> [root at srvmgmt02 ~]# crm_mon -1
> ...
> [snip]
> fence_srvmgmt01 (stonith:fence_intelmodular): Started srvmgmt02.localdomain.local
> fence_srvmgmt02 (stonith:fence_intelmodular): Started srvmgmt02.localdomain.local
>
> and the output above remains true while srvmgmt01 is rebooting but also after it has completed startup and joins the cluster.
> So I presume I have to set an location constraint rule so that it can only run on its node, correct?
Not really. It's not really relevant which node has the fencing device - thats mostly just the node that will check the device is still healthy/correctly configured.
Every node can use the device's configuration when needed.
>
> something llike
> pcs constraint location fence_srvmgmt01 prefers srvmgmt01.localdomain.local=INFINITY
> pcs constraint location fence_srvmgmt02 prefers srvmgmt02.localdomain.local=INFINITY
>
> Gianluca
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