IBM 866011U - Netfinity 5500 - 8660, Hardware Maintenance Manual

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SCSI IDs:
Each SCSI device that is connected to an
individual channel of the RAID controller needs a unique
identification (ID) so that the controller can identify the
devices and ensure that different devices do not attempt to
transfer data at the same time. (The two channels of the
integrated RAID controller operate independently.) If you
need to set IDs for SCSI devices, refer to the instructions
that come with those devices.
The server automatically sets SCSI IDs for hot-swap hard
disk drives, according to the jumper settings on the SCSI
backplanes. The server uses the hard disk drive SCSI IDs
to send status information to the indicator lights above
each hot-swap bay.
The SCSI backplane in the server supports up to six
hot-swap bays. Table 8 shows the default SCSI IDs that
the backplane assigns for hot-swap hard disk drives.
You can change the default ID addresses of the drives by
changing the jumper settings on the SCSI backplane. See
“SCSI backplane option jumpers” on page 250. A
simplified layout of the SCSI backplane is shown in “SCSI
backplane component locations” on page 249.
The processing sequence for SCSI devices is set through
the ServeRAID Configuration Utility program. The
sequence proceeds from the lowest SCSI ID to the highest
(0 to 6, then 8 to 15 determined by the jumper settings).
Termination (internal SCSI devices):
SCSI buses
must be terminated at each end. The ends of the SCSI
buses in the server are already terminated.
All the hot-swap drives in the server have automatic
termination and the RAID controller provides termination at
the other end of the SCSI bus.
If you install SCSI devices in the removable-media bays
(bays A and B), you must disable the termination on the
devices; the RAID controller is already terminated and the
SCSI cable for devices in the removable-media drive bays
has a terminator at the other end. For example, when you
install a SCSI device in a removable-media drive bay (bay
A or B), set its termination to Disable, because the SCSI
cable is already terminated at the end.
Refer to the information that come with the SCSI device for
instructions about setting device jumpers or switches that
control termination.
Table 8. Automatically Assigned SCSI IDs
Bay 1 2 3 4 5 6
ID 0 1 2 3 4 5
Note: The default SCSI ID for the SCSI backplane is 15. The default
SCSI ID for each channel of the RAID controller is 7.
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