Plexes are logical groupings of subdisks that create an area of disk space independent of physical disk size or other restrictions. Replication (mirroring) of disk data is set up by creating multiple data plexes for a single volume. Each data plex in a mirrored volume contains an identical copy of the volume data. Because each data plex must reside on different disks from the other plexes, the replication provided by mirroring prevents data loss in the event of a single-point disk-subsystem failure. Multiple data plexes also provide increased data integrity and reliability.