Choosing the Right Disk Technology in a High Availability Environment DRAFT Version 2.0, August 1996

F/W
SCSI
F/W
SCSI
F/W
SCSI
F/W
SCSI
DRAFT -- Revision 2.0
August 22, 1996Page 19
Figure 4: Typical High Availability Configuration with F/W SCSI Disk Arrays (SCSI
DA)
maximum of 6 F/W SCSI DAs are possible due to a 3-bit DIP switch for the SCSI
address setting. The number is 6 rather than 8 since the two SPUs should have the
highest priority SCSI addresses of 7 and 6. Like the FLDA, SCSI DAs can be used with
HA software as discussed in the section on JBODs.
High Availability Disk Arrays
High Availability Disk Arrays, henceforth called HADA for brevity, are available from HP
in the following models:
A3231A (Model 10 with 2.1 GB disk mechanisms)
A3232A (Model 20 with 2.1 GB disk mechanisms)
A3388A (Model 10 with 4.2 GB disk mechanisms)
A3389A (Model 20 with 4.2 GB disk mechanisms)
HADAs have several features not available in FLDAs and SCSI DAs:
support for multiple concurrent RAID levels
support of RAID level 0/1
up to 20, 3-1/2", 4 GB, 7200 RPM disk mechanisms
easy addition of disk mechanisms online