[Linux-cluster] Resource Shared

[Lon Hohberger]

On Fri, 2006-03-10 at 20:12 +0100, Tano Enzo wrote:
> Hi,
> 
> I have a cluster with 2 nodes RHEL 4 U3, my cluster not use GFS, I have
> a ECM2 shared storage. I have some shared resource: ip address and file
> system. Can I use the shared resource in my service more then one times?
> For example I have a file system /mnt/san/web where more then one
> services access to it. I have created 2 service Test and Test2 which use
> the only file system as resource, but only Test use it, Test2 ignore it.

You can not reference an IP or a regular "fs" (ext3, ext2, reiserfs,
etc) multiple times, because mounting those types of file systems on two
systems is an invitation for a corrupt file system.  Similarly, bringing
up a single IP on two separate systems ... well, generally does not work
well ;)

Currently, you can reuse:

- clusterfs (i.e. GFS; could be extended for other cluster file systems
though)

- netfs (mounting a file system from an NFS server - locks + file system
consistency is handled server-side)

- nfsexport (Meta-resource which is a child of fs or clusterfs to help
with creation of an NFS failover service)

- nfsclient (Resource which describes a target of a failover NFS
service... hostname, wildcard, etc.)

- script (though this should be done with caution!)

Reusing non-shareable resources causes some of the references to be
ignored.  If you want to see what rgmanager thinks about the resource
tree, run:

   rg_test test /etc/cluster/cluster.conf 2>&1 | less

It will tell you of problems it finds in the resource tree (like
exceeding max reference counts for resources, etc.)

-- Lon