IBM 7133 Series Service Manual

| If power is turned off to adapter A, the loop is broken. The 7133 bypass card detects the| loss of voltage, goes into bypass mode, and reconnects the loop. Adapter A is bypassed.Adapter 1 Adapter 2Disk16Disk15Disk14Disk13Disk12Disk11Disk10Disk916 4 5 9 81 13 12Disk1Disk2Disk3Disk4Disk5Disk6Disk7Disk8A B A B| Forced Inline Mode| When a bypass card is jumpered to operate in Forced Inline mode, it behaves as a signal| card of Models 010 and 500; that is, none of its electronic switching circuits are in use.| When a bypass card is in Forced Inline mode, its Mode light is green, and its two Interface| Ready lights are off.| Forced Inline mode is used to disable the switching ability of selected bypass cards in| particular types of subsystem configuration. The types of configuration that might require| Forced Inline mode are those in which:| Two Model 020 or Model 600 7133s are connected to each other. In this type of| configuration, Forced Inline mode removes the risk that a fault condition might break| the connection between the two 7133s. The second example in “Higher-Availability| Configurations for Models 020 and 600” on page 1-56 shows a typical configuration of| this type.| The disk drive modules in one 7133 Model 020 or Model 600 are not all connected to| the same SSA loop. In this type of configuration, Forced Inline mode removes the risk| that a fault condition might cause the disk drive modules of different loops to be| connected to each other.Chapter 1. Reference Information 1-39