[Linux-cluster] HA-LVM and /etc/lvm/lvm.conf

[Redding, Erik]

I'm having a dialog with RH support about configuring HA-LVM within RHCS and I'm trying to see if there are some limitations and thought I'd ping the mailing list on the same subject.  

Is an HA-LVM configuration that only uses LVM tags useful beyond a single volume group?  

I'm attempting to provide a database service along side a pair of HA-NFS services that utilize DRBD and LVM (but drbd isn't the issue). 

on two nodes, rhel-01 and rhel-02, I currently I have three volume groups:  vgTest0, vgTest1, vgTestCluster

vgTest0 and vgTest1 are volume groups that exist on each node, and they provide a single back-end LVM volume to a DRBD resource, so DRBD can leverage the snapshotting technique  during syncs.  Both nodes in the cluster have the same configuration, and DRBD is working fine.  This has been in production for about a month. 

I recently got the SAN resource that is presented to both hosts that I want to roll in LVM so I can utilize snapshots on the volume data.  I don't want to bother with CLVM because I have a use case for snapshotting, so HA-LVM as described: https://access.redhat.com/kb/docs/DOC-3068, I'm doing the second method.  The goal is a failover cluster.  

I've been struggling with how to configure my /etc/lvm/lvm.conf because of the volume_list parameter:


# If volume_list is defined, each LV is only activated if there is a         
# match against the list.                                                    
#   "vgname" and "vgname/lvname" are matched exactly.                        
#   "@tag" matches any tag set in the LV or VG.                              
#   "@*" matches if any tag defined on the host is also set in the LV or VG  
#                                                                            
# volume_list = [ "vg1", "vg2/lvol1", "@tag1", "@*" ]                        

would I go with something like:
volume_list = [ "vgTest0", "vgTestCluster/lvTest0", "@rhel-01", "@*" ]    

I don't get why I need to state a persistent volume group - and if I do, which one?  I've got two persistent groups on each node.  I don't use LVM on the root disk.

Could I somehow expand this out to two HA-LVM volume groups? I don't see a way but thought I'd ask. 



Erik Redding
Systems Programmer, RHCE
Core Systems
Texas State University-San Marcos