[Pacemaker] Announcing Pacemaker Remote - extending high availability outside the cluster stack

David Vossel dvossel at redhat.com
Wed May 15 18:17:51 UTC 2013


Hi,

I'm excited to announce the initial development phase of the Pacemaker Remote daemon is complete and ready for testing in Pacemaker v1.1.10rc2

Below is the first draft of a deployment guide that outlines the initial supported Pacemaker Remote use-cases and provides walk-through examples.  Note however that Fedora 18 does not have the pacemaker-remote subpackage rpm available even though I do reference it in the documentation (this will be changed in a future draft) You'll have to use the 1.1.10rc2 tag in github for now.

Documentation: http://clusterlabs.org/doc/en-US/Pacemaker/1.1-pcs/html-single/Pacemaker_Remote/index.html

For those of you unfamiliar with Pacemake Remote, the pacemaker_remote service is a new daemon introduced in Pacemaker v1.1.10 that allows nodes not running the cluster stack (pacemaker+corosync) to integrate into the cluster and have the cluster manage their resources just as if they were a real cluster node. This means that Pacemaker clusters are now capable of managing both launching virtual environments (KVM/LXC) as well as launching the resources that live within those virtual environments without requiring the virtual environments to run pacemaker or corosync.

Usage of the pacemaker_remote daemon is currently limited to virtual guests such as KVM and Linux Containers, but several future enhancements to include additional use-cases are in the works.  These planned future enhancements include the following.

- Libvirt Sandbox Support
Once the libvirt-sandbox project is integrated with pacemaker_remote, we will gain the ability to preform per-resource linux container isolation with very little performance impact.  This functionality will allow resources living on a single node to be isolated from one another.  At that point CPU and memory limits could be set per-resource in the cluster dynamically just using the cluster config.

- Bare-metal Support
The pacemaker_remote daemon already has the ability to run on bare-metal hardware nodes, but the policy engine logic for integrating bare-metal nodes is not complete.  There are some complications involved with understanding a bare-metal node's state that virtual nodes don't have.  Once this logic is complete, pacemaker will be able to integrate bare-metal nodes in the same way virtual remote-nodes currently are. Some special considerations for fencing will need to be addressed.

- Virtual Remote-node Migration Support
Pacemaker's policy engine is limited in its ability to perform live migrations of KVM resources when resource dependencies are involved.  This limitation affects how resources living within a KVM remote-node are handled when a live migration takes place.  Currently when a live migration is performed on a KVM remote-node, all the resources within that remote-node have to be stopped before the migration takes place and started once again after migration has finished.  This policy engine limitation is fully explained in this bug report, http://bugs.clusterlabs.org/show_bug.cgi?id=5055#c3 

--
David Vossel <dvossel at redhat.com>
irc: dvossel on irc.freenode.net




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