Controller function attributes

Compare important attributes of controller functions.

Table 1. SAS controller functions
Controller functions HA two-system RAID configuration HA two-system JBOD configuration HA single-system RAID configuration
JBOD block size disks supported No1 Yes No1
JBOD block size disks supported Yes No Yes
Mirrored write cache between controllers (for controllers which have write cache) Yes Yes
Mirrored RAID parity footprints between controllers Yes Yes
Dual paths to disks Yes No Yes
Target mode initiator device support Yes No No
Only IBM® qualified disk drives supported Yes Yes Yes
Only IBM qualified disk expansion drawer supported Yes Yes Yes
Tape or optical devices supported No No No
Boot support No No Yes
Operating mode2 Primary adapter or secondary adapter3 Stand-alone adapter3 Primary adapter or secondary adapter3
Preferred dual initiator operating mode2 No preference or primary3 No preference3 No preference or primary3
Dual initiator configuration2 Default3 JBOD HA single path3 Default3
Manage HA access characteristics4 Yes No Yes
  1. JBOD block size (512 or 4096 bytes per sector) disks are not to be used functionally, but will be available to be formatted to RAID block size (528 or 4224 bytes per sector).
  2. Can be viewed by using the Change/Show SAS Controller screen.
  3. This option can be set by using the Change/Show SAS Controller screen.
  4. For information on managing the HA access characteristics for a disk array, see HA access optimization.
Parent topic: Multi-initiator and high availability


Last updated: Wed, May 24, 2017