Bull Escala EPC1200, Connecting Manual, Page: 165 / 224

10-55
Disk Subsystems Cabling Requirements
When it is common to two nodes the disk cabinet can be used as system disk extension or
shared disk subsystem.
In the former case the disks are not shared. Each node possesses its own SCSI bus.
In the latter the configuration allows to support a node failure. There are two SCSI adapters
per node, where each adapter is connected to a distinct SP. The first adapter of a node
allows to access the disks on plates (e.g. A and/or B) allocated to the node, whereas the
second adapter allows to access to the disks on plates (e.g. D and/or E) of the other node. If
a node fails, the other node can recover the activities and access the disks of the failed
node through the second adapter.
However, the mirroring of data implemented through standard mirroring function of AIX
system cannot be done across the two SCSI chains. It means that the failure of a main
adapter is not supported, for the reason that no engineering tests have been so far
performed on that case.
Cabling Diagrams
JDACF01 1 node + 1 controller, 1 SCSI bus, 1 plate
Figure 112.
JDACF01: 1 node + 1 controller, 1 SCSI bus, 1 plate.
JDACF02 1 node + 1 controller, 1 SCSI bus, 2 plates