HP Serviceguard manual About the Volume Monitor, Using the Volume Monitor

3.The mount point packages should not run unless the disk group packages are running.

If the disk groups and mount points are in separate packages, specify the dependencies on the disk group packages in the configuration file.

CAUTION: Once you create the modular CVM disk group and CFS mount point packages, you must administer the cluster with cmcheckconf, cmapplyconf, cmrunpkg, cmmodpkg, and cmrunpkg commands. If you create the legacy CFS packages, you must administer the cluster with CFS commands, including cfsdgadm, cfsmntadm, cfsmount, and cfsumount.

You must not use the HP-UX mount or umount command to provide or remove access to a shared file system in a CFS environment; using these HP-UX commands under these circumstances is not supported. Use cfsmount and cfsumount instead. If you use the HP-UX mount and umount commands, serious problems could occur, such as writing to the local file system instead of the cluster file system. Non-CFS commands could cause conflicts with subsequent CFS command operations on the file system or the Serviceguard packages, and will not create an appropriate multi-node package, which means cluster packages will not be aware of file system changes.

NOTE: The Disk Group (DG) and Mount Point (MP) multi-node packages do not monitor the health of the disk group and mount point. They check that the application packages that depend on them have access to the disk groups and mount points. If the dependent application package loses access and cannot read and write to the disk, it will fail, but that will not cause the DG or MP multi-node package to fail.

4.You create the CFS package, SG-CFS-pkg, with the cfscluster command. It is a system multi-node package that regulates the volumes used by CVM 4.1 and later. System multi-node packages cannot be dependent on any other package.

About the Volume Monitor

Simply monitoring each physical disk in a Serviceguard cluster does not provide adequate monitoring for volumes managed by Veritas Volume Manager from Symantec (VxVM) or logical volumes managed by HP-UX Logical Volume Manager (LVM), because a physical volume failure is not always a critical failure that triggers failover (for example, the failure of a single physical disk within a mirrored volume is not considered critical). For this reason, it can be very difficult to determine which physical disks must be monitored to ensure that a storage volume is functioning properly. The HP Serviceguard Volume Monitor provides a means for simple and effective monitoring of storage volumes.

IMPORTANT: Check the latest version of the release notes (at the address given in the preface to this manual) for information about Serviceguard support for the volume monitor.

Using the Volume Monitor

NOTE: For LVM, using this monitor is an alternative to using Event Monitoring Service (EMS) resource dependencies or System Fault Management/custom defined monitors in Serviceguard using generic resources. EMS does not currently provide a monitor for VxVM.

•See “Using EMS to Monitor Volume Groups” (page 101).

•See “Using Generic Resources to Monitor Volume Groups” (page 100).

Configure the Volume Monitor as a service in a package that requires access to a VxVM or LVM storage volume.

The package can be a failover package or multi-node package. For example, you can configure the monitor as a service in a failover package to monitor a storage volume (or multiple storage volumes) required by the package application. Alternatively, the monitor could be used in a

128 Planning and Documenting an HA Cluster