IBM 7133 Series Service Manual

| SSA Loops and Links| The disk drive modules of the 7133 are connected through two or more SSA links to an| SSA adapter that is located in the using system. The disk drive modules, SSA links, and| SSA adapter are configured in loops. Each loop provides a data path that starts at one| connector of the SSA adapter and passes through a link (external SSA cable) to the disk| drive modules. The loop continues through the disk drive modules, then returns through| another link to a second connector on the SSA adapter.| SSA Connectors of Models 010 and 500| At the back of the 7133 are eight SSA connectors for the external SSA cables. Each pair| of connectors is on a signal card that provides direct connection to a backplane assembly| in the 7133.| SSA Connectors of Models 020 and 600| At the back of the 7133 are eight SSA connectors for the external SSA cables. In Models| 020 and 600, the signal cards as used in Models 010 and 500 have been replaced by| bypass cards, each of which has a pair of SSA connectors. Each bypass card provides| connections to the backplane assemblies of the 7133. If a bypass card loses both of its| external SSA connections, it automatically reconfigures the SSA loop so that the loop| remains complete.| For full details about the operation and configuration of bypass cards, see also “SSA| Bypass Cards (Models 020 and 600)” on page 1-38.| SSA Fibre-Optic Extender Feature| The SSA Fibre-Optic Extender feature permits the 7133 to be connected to SSA adapters| or other devices (for example, other 7133s) through pairs of fiber optic cables. Each end| of a pair of fiber optic cables is connected to a Fibre-Optic Extender. The Fibre-Optic| Extender can be plugged into the SSA connector of a device or adapter. See also “SSA| Fibre-Optic Extenders and Fiber Optic Cables” on page 1-14.Remote Power On Control FeatureThe Remote Power On Control feature permits the using system to control the electricalpower to the 7133. The feature consists of a control unit, a cable that connects thecontrol unit to the 7133, and cables that connect the control unit to the using system. Seealso “Remote-Power-On Control Unit and Cables” on page 1-13.| −48 Volt Power Supply (Model 020 Only)| The −48 Volt Power Supply feature provides fan-and-power supply assemblies and| three-way power cables that allow the 7133 to be connected to −48 volt power sources.| The 7133 must be connected to two separate power sources to ensure that operations are| not interrupted if one power source fails. Two three-way power cables are provided. This| feature is available only on Model 020.1-2 7133 Service Guide