>>> Andrew Beekhof <and...@beekhof.net> schrieb am 23.08.2013 um 02:14 in >>> Nachricht <7e68fa3b-6c15-4e39-ba43-f9a76647f...@beekhof.net>:
> On 22/08/2013, at 7:31 PM, Ulrich Windl <ulrich.wi...@rz.uni-regensburg.de> > wrote: > >> Hi! >> >> Suppose you have an application A that needs two filesystems F1 and F2. The > filesystems are on separate LVM VGs VG1 and VG2 with LVs L1 and L2, > respectively. The RAID R1 and R2 provide the LVM PVs. >> >> (Actually we have one group that has 58 primitives in them with both > dimensions being wider than in this example) >> >> So you can configure >> "group grp_A R1 R2 VG1 VG2 F1 F2 A" (assuming the elements are primitives > already configured) >> >> Now for example if R2 has a problem, the cluster will restart the whole > group of resources, even that sequence that is unaffected (R1 VG1 F1). This > causes extra operations and time for recovery what you don't like. > > So don't put them in a group? > >> >> What you can do now is having parallel execution like this >> "group grp_A (R1 R2) (VG1 VG2) (F1 F2) A" > > You're saying this is currently possible? As it turned out: "not yet" ;-) It only works for explicit "ordering". > If so, crmsh must be re-writing this into something other than a group. This should not be much of a problem; the problem seems to be: How to convert such structures back to the original notation? > >> (Note that this is probably a bad idea as the RAIDs and VGs (and maybe mount > also) most likely use a common lock each that forces serialization) >> >> For the same failure scenario R2 wouldn't be restarted, so the gain is > small. A better approach seems to be >> "group grp_A (R1 VG1 F1) (R2 VG2 F2) A" >> >> Now for the same failure R1, VG1, and F1 will survive; unfortunately if R1 > fails, then everything will be restarted, like in the beginning. >> >> So what you really want is >> "group grp_A ((R1 VG1 F1) (R2 VG2 F2)) A" >> >> Now if R2 fails, then R1, VG1, and F1 will survive, and if R1 fails, then > R2, VG2 and F2 will survive >> >> Unfortunately the syntax of the last example is not supported. > > I'm surprised the one before it is even supported. Groups of groups have > never been supported. I know, and the PDP-8 had 128kB RAM. But things can change. > >> This one isn't either: >> >> group grp_1 R1 VG1 F1 >> group grp_2 R2 VG2 F2 >> group grp_A (grp_1 grp_2) A >> >> So a group of groups would be nice to have. I thought about that long time > ago, but only yesterday I learned about the syntax of "netgroups" which has > exactly that: a netgroup can contain another netgroup ;-) >> >> 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 _______________________________________________ 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
