IBM 7133 Series Service Manual

| Larger Configurations for Models 020 and 600| Four more disk drive modules can be added to the base configuration in one loop. For a| balanced subsystem, however, it is recommended that the two groups of disk drive| modules be connected in two separate loops, each of which is connected to a separate| pair of connectors on the SSA adapter.7133 unit458911612134 3 2 1Using systemA1 A2 B1 B25678| All Models 020 and 600 have three fan-and-power supply assemblies, which provide| redundant power and cooling to all the disk drive modules.| No improvement in performance is gained if the disk drive modules are moved to other| slots and connected in more than two loops by way of an additional SSA adapter.| The cables are described in “SSA Cables” on page 1-43. The internal connections of| Model 020 are shown in “Model 020 Internal Connections” on page 1-18; those of Model| 600 are shown in “Model 600 Internal Connections” on page 1-21.| For information about the rules for SSA loops, see the “Rules for SSA Loops” on| page 1-42.1-52 7133 Service Guide