This display indicates that targets 0， 1， and 6 are in use， and any of the unused targets may be used for the external tape drive.
Remember: Although it is not displayed here， target 7 is always reserved for the SCSI host adapter. Also， as mentioned before， target 5 is reserved for an internal tape drive. If an internal drive is not currently installed you may use target 5 for the external drive. However， if you install an internal tape drive at some point in the future， you will have to assign it to target 5， and you will be forced to reconfigure the external drive with a different target ID. For this reason， in the current scenario the recommended ID would be 4.
If you plan to connect the tape drive to the external connector that is attached to a separate SBus or PCI controller， run the following command to determine the targets in use on all SCSI controllers:
A display will be presented， allowing you to determine the target IDs in use on all controllers. Once you have determined which ID you wish to use， follow the manufacturer's documentation to set the tape drive to this ID.
Attaching the Drive
When adding SCSI devices you must observe proper bus termination for proper operation. The SCSI bus must be terminated at each end. Adding devices to an external connector extends the bus and， therefore， the point of termination is also extended to the last connected device.
A typical configuration of Sun Enterprise servers has the primary SCSI bus extend to an external 68-pin connector， which is located on the rear panel. The external connector can support several different external devices with both narrow， Fast/Wide， and (often) UltraSCSI interfaces. The bus is also auto-terminating; as such， you do not need to worry about enabling or disabling termination when attaching an external device. You need only be concerned with termination of the device itself.
When attaching the external drive， make sure the server has been shut down and powered off. Also， when connecting， ensure that the tape device is not powered up. If the tape device is to be the only external device， simply attach the cable to the connector. Since it is the last device on the bus， make sure it is properly terminated. Then confirm that the device has power， turn the device on， and then turn on the server.
If other devices are already attached to the external connector， the situation gets more complicated. It is advisable that you consult the Sun Enterprise Server Owner's Guide for more detailed installation information. In any case， if you are unfamiliar with SCSI devices， bus length， bus termination， and so on， it is recommended that you read the section that discusses the external SCSI port to gain a better understanding of the requirements for attaching external devices.
Turn on the power to the tape drive and then the server. If you have set the auto-boot? parameter to false， as described above， the system will come up to the ok prompt.
Enter the boot command to perform a reconfiguration reboot， as in the following example:
ok boot -r
If the auto-boot? parameter was not set to false and the server continues to boot into the Solaris OS， log in as root and then create a file named reconfigure in the root directory.
# touch /reconfigure
Reboot the server. The system will check for the existence of the reconfigure file and perform a reconfiguration boot if it exists.
Watch for any boot messages that would indicate a problem with the st.conf file. If problems are found， make note of any line numbers displayed. If errors occur， edit the st.conf file again and perform the reconfiguration reboot again.
The reconfiguration reboot will create the necessary device entries in the /devices and /dev directories.
Testing the Drive
Once the tape device entries have been created successfully， test the tape drive with the mt command. Make sure a tape has been inserted in the drive and run the following command:
# mt -f /dev/rmt/0 status
If other tape devices have been configured in the past， you may have to replace the 0 with a 1， 2， and so on， until you find the number associated with your new drive.
Again continuing with the example of the WangDAT drive， a successful response to the mt command will look something like this:
WangDAT 4mm DAT tape drive:
sense key(0x0)= No Additional Sense residual= 0 retries= 0
file no= 0 block no= 0
Notice that the text displayed on the first line， before "tape drive，" should match the second quoted field of the device configuration line in the st.conf file. Also， note that the specific sense key returned is usually not an issue.
mt may return a message similar to the following:
/dev/rmt/0: No such device or address
This means you should try substituting the 0 with 1， 2， and so on， as mentioned previously. Any other message may indicate a problem with the configuration in the st.conf file. Edit the st.conf file and reboot until the mt command returns the proper status.
When the mt command returns the proper status， the tape drive is correctly configured and ready for use.
For more information， consult the man pages on the mt command.
注:“当添加一个外部 SCSI 磁带机时，必须修改 Solaris OS 配置文件 /kernel/drv/st.conf ”