Possible HA configurations

Compare RAID and JBOD features as used with single- and two-system HA configurations.

Table 1. SAS RAID and JBOD HA configurations
Multi-initiator configuration	HA two system (for example PowerHA™ for AIX®)	HA single system (for example MPIO)
RAID (disks formatted 528 bytes per sector)	Maximum of two controllers Both controllers must have same write cache capability and write cache sizes Both controllers must support "HA two-system RAID" Controllers are in different systems or partitions	Maximum of two controllers Both controllers must have same write cache capability and write cache sizes Both controllers must support "HA single-system RAID" Controllers are in the same system or partition
JBOD (disks formatted 512 bytes per sector)	Maximum of two controllers Both controllers must support HA two-system JBOD Controllers are in different systems or partitions Requires unique setup and cabling	Not supported

The following figures illustrate an example of each configuration.