On 19/10/15 12:34 PM, Ken Gaillot wrote: > Pacemaker supports fencing "topologies", allowing multiple fencing > devices to be used (in conjunction or as fallbacks) when a node needs to > be fenced. > > However, there is a catch when using something like redundant power > supplies. If you put two power switches in the same topology level, and > Pacemaker needs to reboot the node, it will reboot the first power > switch and then the second -- which has no effect since the supplies are > redundant. > > Pacemaker's upstream master branch has new handling that will be part of > the eventual 1.1.14 release. In such a case, it will turn all the > devices off, then turn them all back on again.
How long will it leave stay in the 'off' state? Is it configurable? I ask because if it's too short, some PSUs may not actually lose power. One or two seconds should be way more than enough though. > With previous versions, there was a complicated configuration workaround > involving creating separate devices for the off and on actions. With the > new version, it happens automatically, and no special configuration is > needed. > > Here's an example where node1 is the affected node, and apc1 and apc2 > are the fence devices: > > pcs stonith level add 1 node1 apc1,apc2 Where would the outlet definition go? 'apc1:4,apc2:4'? > Of course you can configure it using crm or XML as well. > > The fencing operation will be treated as successful as long as the "off" > commands succeed, because then it is safe for the cluster to recover any > resources that were on the node. Timeouts and errors in the "on" phase > will be logged but ignored. > > Any action-specific timeout for the remapped action will be used (for > example, pcmk_off_timeout will be used when executing the "off" command, > not pcmk_reboot_timeout). I think this answers my question about how long it stays off for. What would be an example config to control the off time then? > The new code knows to skip the "on" step if the fence agent has > automatic unfencing (because it will happen when the node rejoins the > cluster). This allows fence_scsi to work with this feature. http://i.imgur.com/i7BzivK.png -- Digimer Papers and Projects: https://alteeve.ca/w/ What if the cure for cancer is trapped in the mind of a person without access to education? _______________________________________________ Users mailing list: Users@clusterlabs.org http://clusterlabs.org/mailman/listinfo/users Project Home: http://www.clusterlabs.org Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf Bugs: http://bugs.clusterlabs.org