Accessing a System That Will Not Boot

The procedure in this section describes how to access a system that will not boot from the hard disk. Read "Troubleshooting an Installation from a System Backup" for instructions if a mksysb backup tape fails to boot.

This procedure enables you to get a system prompt so that you may attempt to recover data from the system or perform corrective action that will enable the system to boot from the hard disk.

Notes:

1. This procedure is intended only for experienced users who have knowledge of how to boot or recover data from a system that is unable to boot from the hard disk. Most users should not attempt this procedure but instead should follow local problem-reporting procedures.
2. This procedure is not intended for users who have just completed a New Installation, because the system will not contain data that needs to be recovered. If you are unable to boot from the hard disk after completing a New Installation, follow your local problem-reporting procedures.

The following steps summarize the procedure for accessing a system that will not boot.

1. Boot the system from Volume 1 of the BOS CD-ROM or stacked bootable system installation tape.
2. Select maintenance options.
3. Recover data or perform corrective action using the system prompt.

Prerequisites

• Your system cannot be booted from the hard disk.
• All hardware is installed.
• AIX Version 4.3 Base Operating System (BOS) is installed.
• Your system unit is set to Off.
• Obtain the system key for the key lock (if present) on your system unit.

To Access the System

Use this procedure if you are unable to boot from the hard disk. The beginning of this procedure is similar to the one you used to install the Base Operating System. You will, however, be using the maintenance screens instead of the installation screens to complete this procedure. The maintenance screen illustrations in this procedure are provided as examples only. The actual online screens may be somewhat different in appearance.

1. Turn the system key (if present) to the Service position.
2. Turn on all attached external devices, such as terminals, CD-ROM drives, tape drives, monitors, and external disk drives before turning on the system unit. Do not turn the system unit on until step 5. Turning on the external devices first is necessary so that the system unit can identify them during the startup (boot) process.
   • If you are booting from a network device, refer to AIX Version 4.3 Network Installation Management Guide and Reference.
   • If you are not booting from a network device, go to step 3.
3. Insert Volume 1 of the installation media into the tape or CD-ROM drive. Some CD-ROM drives have a removable disc caddy, while others have a sliding drawer. If the CD-ROM drive on your system has a sliding drawer, place the CD-ROM in the drawer and push the drawer in. If the CD-ROM drive on your system does not have a sliding drawer, insert the CD-ROM into the disc caddy and then insert the caddy into the CD-ROM drive.

   Notes:

   1. You may find that on specific hardware, the tape drive door will not open while the system unit is turned off. If you have trouble opening the tape drive door during installation, use the following procedure:
      1. Turn the system unit on.
      2. Insert the AIX Version 4.3 BOS tape (insert Volume 1 if you received more than one volume).
      3. Turn the system unit off and wait 30 seconds.
   2. On some models that have a door to the tape drive, there may be a waiting period of up to three minutes before the tape drive door opens after you have pressed the button to open the tape drive. Some models also require that the button for the tape drive door be held in the pressed position for a few seconds before the tape drive door will open.
   3. On some models, the eject button must be pressed for at least 2 seconds to eject a CD-ROM that is already in the disc caddy.

4. If you are not using an ASCII terminal, skip to step 5. If you are using an ASCII terminal, set the communications options as follows:
   • Line Speed (baud rate) = 9600
   • Word Length (bits per character) = 8
   • Parity = no (none)
   • Number of Stop Bits = 1
   • Interface = RS-232C (or RS-422A)
   • Line Control = IPRTS
   Set the keyboard and display options as follows:
   • Screen = Normal
   • Row and Column = 24x80
   • Scroll = jump
   • Auto LF (line feed) = off
   • Line Wrap = on
   • Forcing Insert = line (or both)
   • Tab = field
   • Operating Mode = echo
   • Turnaround Character = CR
   • Enter = return
   • Return = new line
   • New Line = CR
   • Send = page
   • Insert Character = space

     Note: If your terminal is an IBM 3151, 3161, or 3164, press the Ctrl+Setup keys to display the Setup Menu and follow the on-screen instructions to set these options. If you are using some other ASCII terminal, refer to the appropriate documents for information about how to set these options. Some terminals have different option names and settings than those listed here.

5. Turn the system unit power switch to the On position. The system begins booting from the installation media. If your system is booting from tape, it is normal for the tape to move back and forth. After several minutes, c31 is displayed in the LED.

   If you have more than one console, each terminal and direct-attach display device (or console) may display a screen that directs you to press a key to identify your system console. A different key is specified for each terminal displaying this screen. If this screen is displayed, then press the specified key on the device to be used as the system console. The system console is the keyboard and display device used for installation and system administration. Press a key on only one console.

6. Enter option 3 to select Start Maintenance Mode for System Recovery from the Welcome to the Base Operating System Installation and Maintenance screen when it is displayed.

   Note: If you customized the bosinst.data file in your installation media to specify a nonprompted installation, the installation and maintenance screens will not be displayed. The system will instead reboot from the installation media using the settings already defined in the bosinst.data file. To access the installation and maintenance screens, you need to override the nonprompted mode. An opportunity to do this occurs when three zeros are displayed on the screen. When you observe the three zeros, enter 000 (zeros) and then the Enter key at the terminal.

   You can select 88 to display help on this or any subsequent screen.

   After you have selected the Start Maintenance Mode for System Recovery option, the Maintenance screen is displayed.

7. Select option 1 , Access a Root Volume Group, from the Maintenance screen. The Warning screen is displayed.
8. Read through the information displayed on the Warning screen. When you are ready to continue, type 0 and press Enter. The Access a Root Volume Group screen is displayed.

9. Select the option for the root volume group whose logical volume information you want to display. The Access a Root Volume Group screen lists all of the volume groups (root and otherwise) on your system. After entering your selection, the Volume Group Information screen is displayed.

   Note: Reviewing the disk and location code information on the Volume Group Information screen enables you to determine whether the volume group you selected was the root volume group. You can return to the Access a Root Volume Group screen if the choice you made was not the root volume group. If you have not chosen a root volume group, you will not be able to continue beyond the Volume Group Information screen.

10. Select one of the options from the Volume Group Information screen and press Enter. Each option does the following:

    Choice 1	Access this volume group and start a shell. Selecting this choice imports and activates the volume group and mounts the file systems for this root volume group before providing you with a shell and a system prompt.
    Choice 2	Access this volume group and start a shell before mounting file systems. Selecting this choice imports and activates the volume group and provides you with a shell and system prompt before mounting the file systems for this root volume group.
    Choice 99	Entering 99 returns you to the Access a Root Volume Group screen.

    After either choice 1 or 2 is selected and processed, a shell and system prompt are displayed.
11. Take appropriate measures to recover data or take action (such as using the bosboot command) to enable the system to boot normally.