Advertisement
SCSI connectors (J7 and J14). For maximum
data throughput, use only Ultra320 SCSI devices.
The MegaRAID 320-2X supports up to 15 Wide
SCSI or Ultra320 devices per channel (14 devices
per channel on storage systems with SAF-TE
enclosures). The maximum SCSI bus cable
length is 12 m.
In addition, you can connect Ultra, Ultra2,
Ultra160, and Ultra320 SCSI devices (although
backward-compatible, SCSI uses the speed of
the slowest device on the bus). The MegaRAID
320 Storage Adapters User's Guide lists the
maximum number of devices and maximum cable
length for each kind of SCSI device.
Disable the SCSI termination on all devices that
are not connected at the end of the SCSI bus.
Use only high-quality ribbon SCSI cables for
internal devices and high-quality round SCSI
cables for external devices.
Step 7
Set Target IDs (TIDs) for the SCSI Devices.
Each connected SCSI device must have a unique
TID, ranging from 0 to 15 for 16-bit devices. Note
that under the DOS Advanced SCSI
Programming Interface, SCSI devices are limited
to SCSI IDs 0–6. The MegaRAID 320-2X is
automatically assigned TID 7, which has the
highest priority. Verify that no two SCSI devices
are set to the same TID. Change the TIDs as
needed. Refer to the SCSI device documentation
if you are not sure how to do this.
Step 8
Set the SCSI Termination.
The SCSI bus, which consists of connected SCSI
cables and SCSI devices, is an electrical
transmission line that must be terminated
properly to minimize signal reflections and
prevent data loss. Disk enclosures normally
handle termination for the SCSI devices in the
enclosure. Refer to your enclosure
documentation for details.
SCSI termination must be set at each end of the
SCSI bus, as shown in
only internal SCSI devices are connected to the
MegaRAID 320-2X. The MegaRAID 320-2X
automatically terminates its end of the SCSI bus
only if internal or external devices are connected
to the SCSI bus. It automatically disables
termination if both internal and external devices
are connected to the bus, because the
MegaRAID 320-2X is then in the middle of the bus.
Figure
3. In this example,
Figure 3 SCSI Termination Example
Termination on Controller
Enabled
For a disk array, set SCSI bus termination so that
removing or adding a SCSI device does not
disturb termination. To do this, connect the
MegaRAID 320-2X to one end of the SCSI cable
and connect a SCSI terminator module to the
other end. Attach the SCSI devices to the
connectors between the two ends and disable
termination on them.
Figure 4
seven SCSI drives. Termination is enabled at the
end of the cable closest to the final SCSI drive,
which is assigned SCSI ID 6.
Figure 4 Termination Enabled on an External
Drive Enclosure
External
SCSI Drives
ID 0
ID 1
ID 2
ID 3
ID 4
ID 5
Termination
ID 6
Enabled
Step 9
Power-up the Computer.
Replace the computer cover and connect the
power cords to all the SCSI devices and to the
computer. Turn on the power to all devices. Be
sure the SCSI devices are powered up before the
computer or at the same time as the computer.
Otherwise, the computer may not recognize the
SCSI devices.
Observe the messages that appear during the
boot process, until you see the message:
Press <Ctrl><M> to run MegaRAID 320 Configuration
Utility, or Press <CTRL><H> for WebBIOS
3 of 4
SCSI Devices
(Termination Disabled on Both)
shows an external drive enclosure with
SCSI
Terminator
Advertisement
