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[Linux-cluster] How to fence a virtual machine in a virtual cluster?


I am running RHEL Virtual Machines as cluster services on RedHat 5.2 Dom0 nodes. The virtual machines use clustered logical volumes for storage, /etc/xen is located on a gfs filesystem. Cluster management using luci from a dedicated admin server. (The entire system works quite well. Some load balancing mechanism on the Dom0 nodes would be fine, but that is another issue...)

Now I need a second cluster, in fact I need a gfs filesystem shared among some of the virtual machines. In general this should not be an issue, but how can I fence a virtual machine inside of a virtual cluster? Technically 'virsh destroy' on the Dom0 host will do the job.

a) I cannot define a script for fencing (at least using luci).
b) There is a fencing method for virtual machines in the RHEL 5.2 cluster, but it is only meant to fence virtual nodes that are part of a mixed cluster of physical and virtual nodes. c) Inside a virtual cluster the "Virtual Machine Fencing" is of no use, because the virtual machine itself is a service in *another* cluster. One would need an option to define the Dom0 host or cluster.

I somehow object to mix physical with virtual machines inside of a cluster (and I do not want to take virtual machines part in the quorum of the physical machines. Hypothetically the virtual machines may fence the physical nodes, thereby shutting down the entire cluster...) . The Dom0-cluster is intended to run VMs only and no other services. The VMs are to provide services, and if they need cluster services, I prefer to define aditional clusters.

Am I missing something? In fact the ability to define a script for fencing would be sufficient from my point of view.

Or is the only real solution to join the VMs in the Dom0 cluster and assign a dedicated failover group to them?

any hint is highly appreciated.

best regards, Gunther

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fn:Gunther Schlegel
org:Riege Software International GmbH;IT Infrastructure
adr:;;Mollsfeld 10;Meerbusch;;40670;Germany
email;internet:schlegel riege com
title:Manager IT Infrastructure

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