Planning the Global Devices and Cluster File Systems

This section provides guidelines for planning global devices and cluster file systems. For more information about global devices and cluster files systems, refer to Sun Cluster 3.0 Concepts.

Guidelines for Highly Available Global Devices and Cluster File Systems

Sun Cluster does not require any specific disk layout or file system size. Consider the following points when planning your global device and cluster file system layout.

• Mirroring - All global devices must be mirrored to be considered highly available.

• Disks - When mirroring, lay out disks so that they are mirrored across disk expansion units.

• Availability - A global device must have a physical connection to more than one node in the cluster to be considered highly available. This configuration can tolerate a single-node failure. A global device with only one physical connection is supported, but it is inaccessible from other nodes if the node with the connection is down.

Mount Information for Cluster File Systems

Consider the following points when planning mount points for cluster file systems.

• Mount point location - Create mount points in the /global directory, unless prohibited by other software products. Using a /global directory enables you to easily distinguish cluster file systems, which are globally available, from local file systems.

• Nesting mount points - Normally, you should not nest the mount points for cluster file systems. For example, do not set up one file system mounted on /global/a and another file system mounted on /global/a/b. Ignoring this rule can cause availability and node boot order problems, because the parent mount point might not be present. The only exception to this rule is if the devices for the two file systems have the same physical node connectivity (for example, different slices on the same disk).