Hi, On Thu, Jan 08, 2009 at 06:07:08AM -0800, Joe Bill wrote: > > On Thu, Nov 20, 2008 at 08:32:52AM -0700, Ryan Kish wrote: > >> - Both nodes have a two ldap configurations, one for running as the > >> master, one for running as the slave. I had to write a couple of OCF > >> scripts for each service (master and slave). > > On 2008-11-20, Dejan Muhamedagic <dejanmm[at]fastmail.fm> wrote: > > > > I guess that this could be better handled by a multi-state > > (master-slave) resource. For which you'd need an appropriate OCF > > RA. Basically, what you already have could be combined in a > > single RA, with two extra operations (actions): promote (slave > > to master) and demote (vice versa). Your configuration would > > also be simpler. > > > > Dejan > > I've recently given multi-state RAs a hard, heavy thought.
Probably they needed it ;-) > I have to disagree on several issues brought up above: > > - the "master/slave, promote/demote" is not a universal > multi-state model and appears, to me at least, to poorly > represent instance relationships between several different > components/applications. What is exactly missing? Can you please be more specific. And provide perhaps some examples. > - the mysql replication model as a master-slave architecture, > by giving the "master"/"slave" moniker values to an option > determining a hosts's role, is a misrepresentation. The fact of > the matter is that one host can run both, the master AND the > backup instances at the same time, and all still make sense and > be coherent with the HA supervisor, depending on the > availability/reachability of nodes. I have yet to figure the > advantage of changing on the fly the state of an > instance, particularly in it's relationship with other > instances, whether the same or different > components/applications are involved, instead of just stopping > and restarting an instance with a different configuration. > > It makes a lot more sense to use the supervisor's logical > instance control facilities than hardcode in the RA Can you define: "supervisor", "logical instance", and "control facilities". > promote/demote rules that have to track and manage the states > of multiple instances, and especially difficult to write > "decision" code that requires to assess and control the states > of several different compnents. Several? I thought one RA would control only one resource. Thanks, Dejan _______________________________________________ Linux-HA mailing list [email protected] http://lists.linux-ha.org/mailman/listinfo/linux-ha See also: http://linux-ha.org/ReportingProblems
