On Fri, Aug 19, 2011 at 01:08:31PM +0200, Dejan Muhamedagic wrote: > Hi, > > On Fri, Aug 19, 2011 at 11:45:24AM +0200, Maloja01 wrote: > > On 08/18/2011 12:19 PM, Ulrich Windl wrote: > > > Hi! > > > > > > Reading the docs, I learned that pacemaker understands more complex > > > dependencies than "group" where resources are strictly sequential. For > > > example one could start a set of resources in parallel, then wait until > > > all are done, then start another set of resources, etc. > > > > > > Now I wonder: > > > 1) Can such a thing (i.e. parallelism) be configured with crm shell? If > > > so, what is the syntax like? > > > > If you have two resources like primitives and they do not have any order > > constraints (neither explizit by a order constraint nor implizit by > > membership in group) such resources are assumed be > > "startable"/"stopable" in parallel and the cluster will do not have any > > peferences about the order. > > I guess that he meant resource sets. There's a slight confusion > regarding those and they were to be reimplemented/redefined in > CRM. Don't know what's the current status. > > > > 2) In some resource groups, not all resources are really required. For > > > example in a RAID1, only one of both legs is really required to start up > > > the RAID (assuming I need to activate some extra resource for each leg of > > > the RAID). Can such a dependency be expressed in CRM? If so, how do you > > > do it? > > > > Beside the fact that I do not see the both legs/ 2 x single leg > > ressources for RAID1 I would say yes that possible but will increase > > the complexity of the cluster and the most important idea behind > > clustering is: "keep it simple". In your case the critical point could > > be the "OR" in the oredring of costraints. > > > > All resouces after your 2 legs solution could be started, if Leg1 OR > > Leg2 is up. Maybe that has to be described via ordering constraints. > > That cannot be described currently, i.e. start B if at least one > of A1 and A2 are running.
You can "work around" that, though: You would need to express your condition via (volatile) node attributes, similar to ping scores. monitor and start action, and maybe post-start notification, of the "legs", could check and add some score to the "raid can run here" attribute. If that score attribute is <= 0 or not defined, raid can not run there. If "enough" legs are available, it can. -- : Lars Ellenberg : LINBIT | Your Way to High Availability : DRBD/HA support and consulting http://www.linbit.com DRBD® and LINBIT® are registered trademarks of LINBIT, Austria. _______________________________________________ Linux-HA mailing list [email protected] http://lists.linux-ha.org/mailman/listinfo/linux-ha See also: http://linux-ha.org/ReportingProblems
