>>> Strahil Nikolov <hunter86...@yahoo.com> schrieb am 02.12.2020 um 22:42 in Nachricht <311137659.2419591.1606945369...@mail.yahoo.com>: > Constraints' values are varying from: > infinity which equals to score of 1000000 > to: > - infinity which equals to score of -1000000 > > You can usually set a positive score on the prefered node which is bigger > than on the other node. > > For example setting a location constraint like this will prefer node1: > node1 - score 10000 > node2 - score 5000 >
The bad thing with those numbers is that you are never sure which number to use: Is 50 enough? 100 Maybe? 1000? 10000? 100000? > In order to prevent unnecessary downtime , you should also consider setting > stickiness. > > For example a stickiness of 20000 will overwhelm the score of 10000 on the > recently recovered node1 and will prevent the resource of being stopped and > relocated from node2 to node1 . Playing all "what happens if" scenarios is rather hard to do, too. > > Note: default stickiness is per resource , while the total stickiness score > of a group is calculated based on the scores of all resources in it. > > Best Regards, > Strahil Nikolov > > > > > > В сряда, 2 декември 2020 г., 16:54:43 Гринуич+2, Dan Swartzendruber > <dswa...@druber.com> написа: > > > > > > On 2020-11-30 23:21, Petr Bena wrote: >> Hello, >> >> Is there a way to setup a preferred node for a service? I know how to >> create constrain that will make it possible to run a service ONLY on >> certain node, or constrain that will make it impossible to run 2 >> services on same node, but I don't want any of that, as in >> catastrophical scenarios when services would have to be located >> together >> on same node, this would instead disable it. >> >> Essentially what I want is for service to be always started on >> preferred >> node when it is possible, but if it's not possible (eg. node is down) >> it >> would freely run on any other node, with no restrictions and when node >> is back up, it would migrate back. >> >> How can I do that? > > I do precisely this for an active/passive NFS/ZFS storage appliance > pair. > One of the VSA has more memory and is less used, so I have it set to > prefer > that host. > > https://clusterlabs.org/pacemaker/doc/en-US/Pacemaker/1.1/html/Clusters_from > _Scratch/_prefer_one_node_over_another.html > > I believe I used the value infinity, so it will prefer the 2nd host over > the 1st if at all possible. My 'pcs constraint': > > [root@centos-vsa2 ~]# pcs constraint > Location Constraints: > Resource: group-zfs > Enabled on: centos-vsa2 (score:INFINITY) > Ordering Constraints: > Colocation Constraints: > Ticket Constraints: > > _______________________________________________ > Manage your subscription: > https://lists.clusterlabs.org/mailman/listinfo/users > > ClusterLabs home: https://www.clusterlabs.org/ > _______________________________________________ > Manage your subscription: > https://lists.clusterlabs.org/mailman/listinfo/users > > ClusterLabs home: https://www.clusterlabs.org/ _______________________________________________ Manage your subscription: https://lists.clusterlabs.org/mailman/listinfo/users ClusterLabs home: https://www.clusterlabs.org/
