On Mon, Oct 4, 2010 at 10:36 PM, Andreas Kurz <[email protected]> wrote: > Hello, > > On 10/04/2010 05:36 PM, Dejan Muhamedagic wrote: >> Hi, >> >> On Mon, Oct 04, 2010 at 04:01:50PM +0100, Matthew Richardson wrote: >> I've been playing with pacemaker for a while now, and have recently >> seena user stung by an issue I had when I first started - namely that >> colocation constraints are limited to 2 entries, unless sets are used. >> >> Thus: >> >> colocation ok inf: A B >> >> is allowed (obviously!) >> >> colocation sets_ok inf: A (B) (C) >> >> is also allowed. >> >> However: >> >> colocation not_ok inf: A B C >> >> isn't valid, though a user might expect it to be equal to the set-based >> contraint. >> >>> Hmm, last time I looked it worked. How do you know that it's not >>> valid? > > I think what Matthew means is: > > colocation ok inf: A B ... produces a colocation constraint A-follows-B > > colocation not_ok inf: A B C ... implicitely configures a resource set > expressing C-follows-B-follows-A, which is exatly the other way round.
I'm pretty sure I've brought this up before and indicated that I wasn't a fan of the shell's behavior in this instance. IMHO, "A B C" without the brackets should not be allowed. > > colocation sets_ok inf: A (B) (C) ... configures three resource sets > that behave like (as a lot of user seem to expect from the previous > example) A-follows-B-follows-C > > Dejan, what are your thougts about let the shell "hide" the reversed > behavior of colocation resource sets and let this: > > colocation not_ok inf: A B ( C D ) F G > > ... create: > > <rsc_colocation id="not_ok" score="INFINITY" > > <resource_set id="collocated-set-1" sequential="true"> > <resource_ref id="B"/> > <resource_ref id="A"/> > </resource_set> > <resource_set id="collocated-set-2" sequential="false"> > <resource_ref id="D"/> > <resource_ref id="C"/> > </resource_set> > <resource_set id="collocated-set-3" sequential="true"> > <resource_ref id="G"/> > <resource_ref id="F"/> > </resource_set> > </rsc_colocation> > > ... or convince Andrew to change resource sets to _not_ have the same > colocation semantics as groups ... whatever is easier ;-) > > Regards, > Andreas > >> >>> Thanks, >> >>> Dejan >> >> I would like to suggest 2 potential solutions to this: >> >> 1) (simple) Provide a warning/error message when someone constructs this >> invalid constraint. >> >> 2) (more complex) Translate this constraint to a meaningful set - i.e >> change 'A B C' to 'A (B) (C)' >> >> I'm not sure whether or not the 2nd option makes sense or whether it >> adds some extra level of confusion or uncertainty to its behaviour. >> >> Any comments? I'm happy to do some work to submit a patch to the shell >> to at least do the basic checking, though this might not be the best >> place (or indeed the best patch) to achieve these, if people think >> they're worthwhile suggestions. >> >> Thanks, >> >> Matthew >> >>> > -- > The University of Edinburgh is a charitable body, registered in > Scotland, with registration number SC005336. >>> > _______________________________________________ > Linux-HA mailing list > [email protected] > http://lists.linux-ha.org/mailman/listinfo/linux-ha > See also: http://linux-ha.org/ReportingProblems >> _______________________________________________ >> Linux-HA mailing list >> [email protected] >> http://lists.linux-ha.org/mailman/listinfo/linux-ha >> See also: http://linux-ha.org/ReportingProblems > > _______________________________________________ > Linux-HA mailing list > [email protected] > http://lists.linux-ha.org/mailman/listinfo/linux-ha > See also: http://linux-ha.org/ReportingProblems > _______________________________________________ Linux-HA mailing list [email protected] http://lists.linux-ha.org/mailman/listinfo/linux-ha See also: http://linux-ha.org/ReportingProblems
