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

DRAFT -- Revision 2.0
August 22, 1996Page 39
The Performance Load Factor is normalized to a modern JBOD, which can sustain a
3.7 MB/sec transfer rate. For example, a HADA disk array Storage Processor can
sustain an 8 MB/sec transfer rate, so it counts as two devices.
Table G summarizes the Performance Load Factors associated with each device type.
Table G: Performance Load Factor by Device Type
Device Type Performance
Load Factor
Standalone JBOD 1
Each storage module in a HASS
1
HADA disk array with one storage processor 2
HADA disk array with two storage processors, but each storage 2
processor is attached to a different F/W SCSI bus
(on each bus)
HADA disk array with two storage processors on a single bus 4
(NOT a supported configuration in an HA cluster)
AutoRAID disk array with two controllers, each on a different F/W 2
SCSI bus (on each bus)
Each active host adaptor on the same F/W SCSI bus
1.5
Here are several examples giving configurations that add up to the maximum of 11.5
Performance Loads based on the numbers in the above Table G:
A single system
1.5 for the one active host adapter AND
10.0 for 5 HADA disk arrays each with one Storage Processor each OR
8.0 for 2 HADA disk arrays each with two Storage Processors each OR
10.0 for 10 JBODs
A two-node HA cluster with only one node active on the F/W SCSI bus
1.5 for the one active host adapter AND
10.0 for 5 HADA disk arrays each with one Storage Processor each OR
8.0 for 2 HADA disk arrays each with two Storage Processors each OR