For information about the purpose and function of global devices, see Devices in Sun Cluster Overview for Solaris OS and Global Devices in Sun Cluster Concepts Guide for Solaris OS.
Sun Cluster software does not require any specific disk layout or file system size. Consider the following points when you plan your layout for global devices.
Mirroring – You must mirror all global devices for the global device to be considered highly available. You do not need to use software mirroring if the storage device provides hardware RAID as well as redundant paths to disks.
Disks – When you mirror, lay out file systems so that the file systems are mirrored across disk arrays.
Availability – You must physically connect a global device to more than one node in the cluster for the global device to be considered highly available. A global device with multiple physical connections can tolerate a single-node failure. A global device with only one physical connection is supported, but the global device becomes inaccessible from other nodes if the node with the connection is down.
Swap devices - Do not create a swap file on a global device.
Non-global zones - Global devices are not directly accessible from a non-global zone. Only cluster-file-system data is accessible from a non-global zone.