I have an issue that I'm not sure how to resolve so feedback is welcome.
I need to mount a local NFS file system on my node before I start a
VirtualDomain resource which depends on it, however, the NFS server is
itself a resource on the cluster.
This causes the cart before the horse. If I insert a node into a
running cluster, this is pretty simple, mount nfs before starting
pacemaker, and if a VirtualDomain resource is immediately started, we
already have what we need. But that doesn't work on a cold cluster
because if I try to mount NFS on the node before the cluster starts the
NFS server, the mount fails. If I always mount NFS after I start
pacemaker, then pacemaker will usually try to start VirtualDomain
resources before I can get further in the boot and mount NFS which
causes the VirtualDomain resource to fail to start.
I think I need one of the following fixes:
1. Delayed start on VirtualDomain resources so that we give time to get
the file system mounted which feels hackish as it's the old sleep fix
for race conditions.
2. Make the nfs mount itself a resource and make VirtualDomain
resources depend on it. In order for this to work each node would need
it's own nfs mount resource, and VirtualDomain resources that can run on
any node would need to depend on the nfs mount resource of whatever node
they decide to run on but not the nfs mount resource of any other node.
I'm not sure how to make this work because the dependency changes with
what node the VirtualDomain resource is started on.
3. Make the VirtualDomain resource call a script on start/migrate that
simply looks for the nfs mount, and if missing, try to mount. This seems
less hackish, but will ensure that we always try to get the nfs mount
going the first time the resource is moved/started there.
Any ideas or thoughts would be very helpful and appreciated.
Matt
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