To mirror all multihost disks in a Sun Cluster configuration enables the configuration to tolerate single-disk failures. Sun Cluster software requires that you mirror all multihost disks across disk expansion units. You do not need to use software mirroring if the storage device provides hardware RAID as well as redundant paths to disks.
Separate disk expansion units – Each submirror of a given mirror or plex should reside in a different multihost disk-expansion unit.
Disk space – Mirroring doubles the amount of necessary disk space.
Number of metadevices or volumes – Under Solstice DiskSuite/Solaris Volume Manager software, mirrors consist of other Solstice DiskSuite metadevices or Solaris Volume Manager volumes such as concatenations or stripes. Large configurations might contain a large number of metadevices or volumes.
For more information about multihost disks, see “Multihost Disk Storage” in Sun Cluster Overview for Solaris OS and Sun Cluster Concepts Guide for Solaris OS.