On Wed, Jan 25, 2023 at 3:49 PM Antony Stone <[email protected]> wrote: > > Hi. > > I have a corosync / pacemaker 3-node cluster with a resource group which can > run on any node in the cluster. > > Every night a cron job on the node which is running the resources performs > "crm_standby -v on" followed a short while later by "crm_standby -v off" in > order to force the resources to migrate to another node member. > > We do this partly to verify that all nodes are capable of running the > resources, and partly because some of those resources generate significant log > files, and if one machine just keeps running them day after day, we run out of > disk space (which effectively means we just need to add more capacity to the > machines, which can be done, but at a cost). > > So long as a machine gets a day when it's not running the resources, a > combination of migrating the log files to a central server, plus standard > logfile rotation, takes care of managing the disk space. > > What I notice, though, is that two of the machines tend to swap the resources > between them, and the third machine hardly ever becomes the active node. >
Pacemaker simply checks each eligible node whether it can run a resource and I believe the order of the node list does not change (at least as long as there is no join/leave event). So effectively the resource just oscillates between the first two nodes in the list. > Is there some way of influencing the node selection mechanism when resources > need to move away from the currently active node, so that, for example, the > least recently used node could be favoured over the rest? > I do not think pacemaker even knows which node is "the least recently used", it does not keep this history. You can add a rule to define location constraint based on some node attribute(s) and set this attribute in the same script where you call crm_standby. E.g. you could set a timestamp on the node where the resource is currently active before doing crm_standby and select the node with the oldest timestamp (I do not think pacemaker supports such computation in its rules). _______________________________________________ Manage your subscription: https://lists.clusterlabs.org/mailman/listinfo/users ClusterLabs home: https://www.clusterlabs.org/
