11.01.2018 19:21, Ken Gaillot пишет: > On Thu, 2018-01-11 at 01:16 +0100, Jehan-Guillaume de Rorthais wrote: >> On Wed, 10 Jan 2018 12:23:59 -0600 >> Ken Gaillot <kgail...@redhat.com> wrote: >> ... >>> My question is: has anyone used or tested this, or is anyone >>> interested >>> in this? We won't promote it to the default schema unless it is >>> tested. >>> >>> My feeling is that it is more likely to be confusing than helpful, >>> and >>> there are probably ways to achieve any reasonable use case with >>> existing syntax. >> >> For what it worth, I tried to implement such solution to dispatch >> mulitple >> IP addresses to slaves in a 1 master 2 slaves cluster. This is quite >> time >> consuming to wrap its head around sides effects with colocation, >> scores and >> stickiness. My various tests shows everything sounds to behave >> correctly now, >> but I don't feel really 100% confident about my setup. >> >> I agree that there are ways to achieve such a use case with existing >> syntax. >> But this is quite confusing as well. As instance, I experienced a >> master >> relocation when messing with a slave to make sure its IP would move >> to the >> other slave node...I don't remember exactly what was my error, but I >> could >> easily dig for it if needed. >> >> I feel like it fits in the same area that the usability of Pacemaker. >> Making it >> easier to understand. See the recent discussion around the gocardless >> war story. >> >> My tests was mostly for labs, demo and tutorial purpose. I don't have >> a >> specific field use case. But if at some point this feature is >> promoted >> officially as preview, I'll give it some testing and report here >> (barring the >> fact I'm actually aware some feedback are requested ;)). > > It's ready to be tested now -- just do this: > > cibadmin --upgrade > cibadmin --modify --xml-text '<cib validate-with="pacemaker-next"/>' > > Then use constraints like: > > <rsc_colocation id="id0" score="100" > rsc="rsc1" > with-rsc="clone1" with-rsc-instance="1" /> > > <rsc_colocation id="id1" score="100" > rsc="rsc2" > with-rsc="clone1" with-rsc-instance="2" /> > > to colocate rsc1 and rsc2 with separate instances of clone1. There is > no way to know *which* instance of clone1 will be 1, 2, etc.; this just > allows you to ensure the colocations are separate. >
Is it possible to designate master/slave as well? > Similarly you can use rsc="clone1" rsc-instance="1" to colocate a clone > instance relative to another resource instead. > > For ordering, the corresponding syntax is "first-instance" or "then- > instance" as desired. > > I believe crm shell has higher-level support for this feature. > > Personally, I think standard colocations of rsc1 and rsc2 with clone1, > and then an anticolocation between rsc1 and rsc2, would be more > intuitive. You're right that the interactions with stickiness etc. can > be tricky, but that would apply to the alternate syntax as well. > _______________________________________________ Users mailing list: Users@clusterlabs.org http://lists.clusterlabs.org/mailman/listinfo/users Project Home: http://www.clusterlabs.org Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf Bugs: http://bugs.clusterlabs.org
