Hi! Maybe you should show the resources and their dependencies. If the VIP is in a group, what else is in that group? In my first reading I thought you want to manage one resource in a group, but still want the group to move. Is that right?
Kind regards, Ulrich Windl > -----Original Message----- > From: Users <users-boun...@clusterlabs.org> On Behalf Of Eugen Block > Sent: Monday, January 27, 2025 3:41 PM > To: Cluster Labs - All topics related to open-source clustering welcomed > <users@clusterlabs.org> > Subject: [EXT] Re: [ClusterLabs] Clarification on resource groups > > Thanks for your response. > > Maybe I didn't explain myself well enough, I can go into more detail > if necessary. I wanted to focus on resource groups first. But let me > give an example from a recent upgrade that didn't go as smooth as > planned. > > We have a virtual IP colocated with haproxy, which redirects > (OpenStack) API calls to the backend servers. Since there are multiple > instances of those API services running, the services are still > responsive and functioning properly. > So I put one node in maintenance mode to be able to stop all the > systemd units wrt OpenStack, but not Galera and RabbitMQ. This node > didn't have the VIP at the time. When I was done with the first node, > everything was still good. But putting the node with the VIP into > maintenance mode was a mistake: > > During the system update there were also updates for network related > packages (I hadn't noticed that on the first node), leading to a > restart of the network service, causing the VIP to vanish. But since > pacemaker couldn't move the resource, we had an API outage for > OpenStack. To avoid that in the future, I will only put some of the > resources into maintenance mode, not all of them. That way pacemaker > will be able to move the VIP and HAProxy to the already upgraded node, > so there will only be a tiny disruption, but most clients won't > notice. I successfully tested that behavior on a test cloud, hence I'm > confident that this is the right approach in my case. > > If I put the entire cluster into maintenance mode, the VIP wouldn't be > moved away when the network gets interrupted, that would cause a > client disruption. > > Thanks! > Eugen > > > Zitat von "Windl, Ulrich" <u.wi...@ukr.de>: > > > Hi! > > > > Assuming you know what "location" refers to. What you are doing > > makes very little sense IMHO: > > When working on a service that needs some IP, it makes little sense > > to put the service in maintenance mode, but not the IP: > > Imagine something bad happens to the network and the cluster wants > > to move the IP while you are working on the service. Would you want > > that to happen? Also (as I see it), to move the group, the cluster > > would stop the service first, but when it's in maintenance mode, it > > can't. So it can't move the group (and thus the IP neither). > > Pertsonally I put the cluster in maintenance mode as a whole, > > preferably for a rather short time. Unless services fail very > > frequently, this seems to be a safe mode of operation to me. > > > > Kind regards, > > Ulrich Windl > > > >> -----Original Message----- > >> From: Users <users-boun...@clusterlabs.org> On Behalf Of Eugen Block > >> Sent: Monday, January 13, 2025 1:17 PM > >> To: users@clusterlabs.org > >> Subject: [EXT] [ClusterLabs] Clarification on resource groups > >> > >> Hi, > >> > >> I'm hoping to get some clarification on my understanding of resource > >> groups [0]. It states: > >> > >> > One of the most common elements of a cluster is a set of resources > >> > that need to be located together, start sequentially, and stop in > >> > the reverse order. > >> > >> Especially the "located together" attribute confuses me. > >> > >> I'll try to provide some context: > >> I have a couple of systemd services as clones and some multi-state > >> resources such as galera and rabbitmq, running on two pacemaker nodes. > >> In case of an upgrade or any kind of maintenance, I want to use the > >> maintenance mode for some resources, but not all of them. For example, > >> I want the virtual IP, galera and rabbitmq to be still managed while > >> the rest is in maintenance mode. So currently, I would run a for loop > >> on the systemd services only, putting them into maintenance. This way, > >> if the network stack is updated or something, the virtual IP would be > >> moved to the other node. IIUC, this is not covered by the resource > >> groups, is it? > >> > >> Or should I have used it when building the cluster from scratch, > >> creating groups containing my systemd services as primitives? And then > >> clone a group? > >> > >> Is there another way of achieving that? I'd appreciate any comments! > >> > >> Thanks! > >> Eugen > >> > >> [0] > >> > https://clusterlabs.org/projects/pacemaker/doc/2.1/Pacemaker_Explained/ > >> singlehtml/index.html#group-resources > >> > >> _______________________________________________ > >> Manage your subscription: > >> https://lists.clusterlabs.org/mailman/listinfo/users > >> > >> ClusterLabs home: https://www.clusterlabs.org/ > > _______________________________________________ > > Manage your subscription: > > https://lists.clusterlabs.org/mailman/listinfo/users > > > > ClusterLabs home: https://www.clusterlabs.org/ > > > > _______________________________________________ > Manage your subscription: > https://lists.clusterlabs.org/mailman/listinfo/users > > ClusterLabs home: https://www.clusterlabs.org/ _______________________________________________ Manage your subscription: https://lists.clusterlabs.org/mailman/listinfo/users ClusterLabs home: https://www.clusterlabs.org/
