[Linux-cluster] Minimum requirements for clvm only?

[Patrick Caulfield]

Nate Carlson wrote:
> Hey all,
> 
> I'm building a new system with shared FC storage primarily to allow Xen
> virtual machines to be migrated between host systems. I'd like to be
> able to use LVM or some similar system that allows me to name my own
> volumes, but don't need shared storage, rgmanager, etc. What are the
> minimum requirements to just get clvm working? I'm assuming I don't need
> fence devices and such for this, as those are primarily used to ensure
> that a system is writing to a filesystem when it's not supposed to?
> Also, are there any alternatives to clvm that may be better suited for
> this case?

If you don't need/have shared storage then I don't think you need clam at all. The whole point of clvm is to provide central and
cluster-coherent management of shared Logical volumes.

However you do say you have shared storage, but don't need it which is slightly confusing! So assuming you do have AND want shared
storage then clvm will probably be able to help. It does require the Red Hat cluster suite components such as ccs/cman/dlm(or gulm)
but you can do without fencing and the other bits you mention.

Actually, in theory you can get away without ccsd too if you really want to (the -X switch to cman_tool join will take command-line
arguments for the node) but it's probably easier to use it than not - particularly cluster suite in RHEL5 will require it.


As for recommending alternatives, it's hard to say for certain without knowing more about exactly what it is you are trying to do.
-- 

patrick