There are three identically loaded SCSI hard disk drives for the two real-time computers at the summit. They were last synchronized on March 28, 2005. Two of the three drives are used by the antenna computer and the AOS backend computer. The remaining one is kept as spare. Personality of each drive, like host name, IP address, and custom device drivers being loaded, can be switched by simply running a reconfiguration script. Please follow the instructions below.
The spare disk drive can usually be found in the vicinity of the antenna computer or the AOS backend computer in the AOS room. The drive may already be connected to one of the computers for maintenance purpose. If that is the case, both the computers may have to be shut down.
Login from the console either as root or cso and reboot the system by /usr/local/sbin/reboot -aN. When the message "AutoBoot about to Begin... Press <ESC> to Bypass, <SPC> to Continue" appears, press ESC to break out to the debugger prompt. Turn off the computer. Leave the console line connection active because it will be needed later.
Turn off the disk drive. Then replace it with a spare drive. Make sure its SCSI ID is set to zero and its unused SCSI connector is properly terminated. Turn the spare disk on.
Turn the computer back on and boot the system. If the spare disk has not been used before, the system boots up with a host name of lani and an IP address of 128.171.86.91. No custom device drivers are loaded in this case. If it has been used already, the system may boot up either with the right configuration or with the wrong configuration. If the antenna computer boots up as hau, or the AOS backend computer boots up as bck, the next step is not necessary.
Login from the console as either root or cso. Execute /usr/local/sbin/reconfigure hau for the antenna computer, or execute /usr/local/sbin/reconfigure bck for the AOS backend computer. Reboot the system by /usr/local/sbin/reboot -aN.