>>> Maloja01 <maloj...@arcor.de> schrieb am 19.08.2011 um 11:45 in Nachricht <4e4e30b4.6080...@arcor.de>: > 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?
My initial thought was a syntax like this sequence seq a b c (d e) f g meaning a nd b are executed sequentially, then d and e are executed in parallel, and once finished f an g are executed sequentially. The crm shell would have to "compile" the low-level statements from the high-level spec. > > 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. > > > > > 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 You could imagine two iSCSI disks that are configured as a resource each. > 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. My initial idea was something like sequence seq a b (needed=1 legA legB) c d meaning that a and be are executed sequentially, then legA and legB are executed in parallel. The parallel execution is considered successful if `needed' resources did start. Note no resourcename can contain a '=', so this might actually work. If the parallel execution was successful c and d would be executed. Again crm shell would have to compile the low-level statements. > > 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. > > > > > I'd wish (I know what you will reply ;-)) that could be expressed with the > crm shell. > really? - why I wrote my answer, if you already knew it ;-) I was expecting: "Please send a patch" ;-) Regards, Ulrich _______________________________________________ Linux-HA mailing list Linux-HA@lists.linux-ha.org http://lists.linux-ha.org/mailman/listinfo/linux-ha See also: http://linux-ha.org/ReportingProblems
