Managing HP Serviceguard for Linux, Tenth Edition, September 2012

Logical Volume and File System Planning
Use logical volumes in volume groups as the storage infrastructure for package operations
on a cluster. When the package moves from one node to another, it must still be able
to access the same data on the same disk as it did when it was running on the previous
node. This is accomplished by activating the volume group and mounting the file system
that resides on it.
In Serviceguard, high availability applications, services, and data are located in volume
groups that are on a shared bus. When a node fails, the volume groups containing the
applications, services, and data of the failed node are deactivated on the failed node
and activated on the adoptive node (the node the packages move to). In order for this
to happen, you must configure the volume groups so that they can be transferred from
the failed node to the adoptive node.
NOTE: To prevent an operator from accidentally activating volume groups on other
nodes in the cluster, versions A.11.16.07 and later of Serviceguard for Linux include a
type of VG activation protection. This is based on the “hosttags” feature of LVM2.
This feature is not mandatory, but HP strongly recommends you implement it as you
upgrade existing clusters and create new ones. See “Enabling Volume Group Activation
Protection” (page 173) for instructions.
As part of planning, you need to decide the following:
• What volume groups are needed?
• How much disk space is required, and how should this be allocated in logical
volumes?
• What file systems need to be mounted for each package?
• Which nodes need to import which logical volume configurations.
• If a package moves to an adoptive node, what effect will its presence have on
performance?
• What hardware/software resources need to be monitored as part of the package?
You can then configure these as generic resources in the package and write
appropriate monitoring scripts for monitoring the resources.
NOTE: Generic resources influences the package based on the status. The actual
monitoring of the resource should be done in a script and this must be configured
as a service. The script sets the status of the resource based on the availability of
the resource. See “Monitoring Script for Generic Resources” (page 340).
Create a list by package of volume groups, logical volumes, and file systems. Indicate
which nodes need to have access to common file systems at different times.
HP recommends that you use customized logical volume names that are different from
the default logical volume names (lvol1, lvol2, etc.). Choosing logical volume names
Package Configuration Planning 121