Novell LINUX ENTERPRISE 11 - HIGH AVAILABILITY, Manual, Page: 127 / 298

13
Cluster LVM
When managing shared storage on a cluster, every node must be informed about changes
that are done to the storage subsystem. The Linux Volume Manager 2 (LVM2), which
is widely used to manage local storage, has been extended to support transparent man-
agement of volume groups across the whole cluster. Clustered volume groups can be
managed using the same commands as local storage.
To implement cLVM, a shared storage setup — such as provided by a Fibre Channel,
FCoE, SCSI or iSCSI SAN or DRBD — must be available.
Internally, cLVM uses the Distributed Lock Manager (DLM) component of the cluster
stack to coordinate access to the LVM2 metadata. As DLM in turn integrates with the
other components of the stack such as fencing, the integrity of the shared storage is
protected at all times.
cLVM does not coordinate access to the shared data itself; to do so, you must configure
OCFS2 or other cluster-aware applications on top of the cLVM-managed storage.
13.1 Configuration of cLVM
To setup a cluster-aware volume group, several tasks must be completed successfully:
1 Change the locking type of LVM2 to be cluster-aware.
Edit the file
/etc/lvm/lvm.conf
and locate the line:
locking_type = 1
Cluster LVM 117