[Linux-cluster] clvmd without GFS?

[Patrick Caulfield]

On Tue, Oct 26, 2004 at 04:52:12PM -0500, Matt Mitchell wrote:
> Just seeking some opinions here...
>  
> So in the effort to get something set up quickly I think I am going to 
> try setting up a regular filesystem on top of LVM2.  Since these disks 
> are shared, we'll at least have a warm-failover capability if the server 
> machine goes down.  (If I have the energy I will set up cluster failover 
> to take care of that automatically too.)  Question I have is, how does 
> clvmd impact this?  Without it I know you have to force LVM2 to read the 
> VG information off of disk when moving partitions between nodes; does 
> clvmd make this step unnecessary?  Also, is it possible to reliably 
> mount read-only a snapshot of a LV still mounted read-write on the other 
> node?  (It seems like it should be.)

You can use clvmd without GFS quite happily and it will certainly make sure
that the LVM metadata is consistent across the cluster - that's it's job. 

You cannot mount a snapshot (even RO) on another node though. The snapshot needs
to be kept informed about changes to the origin LV so it can read the data from
the copy-on-write area. 

Clustered snapshots are being worked on.

patrick