On 11/29/2011 04:28 PM, Muhammad Sharfuddin wrote: > On Mon, 2011-11-28 at 21:47 +0100, Tim Serong wrote: >> On 11/28/2011 06:54 PM, Muhammad Sharfuddin wrote: >>> is it good/required to create order constraint for sbd resource >>> >>> I am using following fencing resource: >>> >>> primitive sbd_stonith stonith:external/sbd \ >>> meta target-role="Started" \ >>> op monitor interval="3000" timeout="120" \ >>> op start interval="0" timeout="120" \ >>> op stop interval="0" timeout="120" \ >>> params >>> sbd_device="/dev/disk/by-id/scsi-360080e50002377b8000002ff4e4bc873" >>> >>> I have following order constraints: >>> >>> order resA-before-resB inf: resA resB symmetrical=true >>> order resB-before-resC inf: resB resC symmetrical=true >>> >>> should I also create another constraint for sbd like: >>> >>> order sbd_stonith-before-resA inf: sbd_stonith resA symmetrical=true >>> >>> please help/suggest. >> >> No. The STONITH resource doesn't need to be running in order for your >> other resources to be operable (hence no need for an order constraint). >> >> Regards, >> >> Tim > true, but if there is an order constraint for the STONITH resource, then > it will at least make it sure that no other resource will be start > before the STONITH resource. > > e.g: > order sbd_stonith-before-resA inf: sbd_stonith resA symmetrical=true > > order resA-before-resB inf: resA resB symmetrical=true > order resB-before-resC inf: resB resC symmetrical=true > > Because I stopped all the resources including STONITH resource(and > stopping any resource sets the 'target-role="Stopped"'), then started > all other resources else/except the STONITH resource, so at that time my > cluster has no fencing resource available.
So, don't stop the STONITH resource :) Side point: if you use "crm configure property stop-all-resources=true", this will stop all resources *except* for any STONITH resources. The point being, you do always want them running... > So in order to protect the cluster I thought that there should(must) be > an order constraint that specifies that no other resource(s) will be > start if STONITH resource is stopped/unavailable. > > Please suggest/recommend You should generally be OK without order constraints on STONITH resources. I don't recall seeing any other systems where people had created these constraints. I should also note that if, say, your STONITH resource is running on node-0 and that node dies, the cluster will start the STONITH resource on node-1, to kill node-0. It's smart enough. Worst case, if your STONITH resource is completely broken, and a node fails and thus can't be killed, the cluster will sit there and log errors to syslog about its inability to kill the misbehaving node. (Question for everyone else: did I miss anything?) Regards, Tim -- Tim Serong Senior Clustering Engineer SUSE [email protected] _______________________________________________ Linux-HA mailing list [email protected] http://lists.linux-ha.org/mailman/listinfo/linux-ha See also: http://linux-ha.org/ReportingProblems
