Adding Applications to the Shutdown Process

2.5 Troubleshooting Boot Problems

There are many contributing factors towards a system failure. A system can fail due to mishandling, if someone intentionally accesses and ends up corrupting it, when conditions, such as a power failure, corrupt the Boot Logical Volume (BLV), or a disk encounters many bad blocks under which the system becomes un-usable. Any of these conditions may prevent the system from restarting.

The sections that follow contain a discussion of the situations where the system will not boot and how to correct the problems.

2.5.1 Accessing a System that Will Not Boot

If you are unable to boot your system, the first step is to access the system and see what is the probable cause of the failure. 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.

The following steps summarize the procedure for accessing a system that will not boot. For detailed information, see the AIX Version 4.3 Installation Guide, SC23-4112.

In order to access the system:

  1. 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. Turn on the system unit to allow the installation media to be loaded.
  2. Insert Volume 1 of the installation media into the tape or CD-ROM drive and power the system unit off.
  3. Turn the system key (if present) to the service position or alternatively press F5 (or 5) on PCI-based systems to boot from the tape or CD-ROM drive (during step 4).
  4. Turn the system unit power switch to the on position. When booting from alternate media, a screen will appear (before the following figure) asking you to press a function key (such as F1) to select the proper display as the system console. Each display attached to the system will receive a function key number in order to identify it as the system console. The system begins booting from the installation media. After several minutes, C31 is displayed in the LED (if your system has an LED; otherwise, a screen similar to the one in Figure 2 is shown).

    Figure 2: BOS Installation and Maintenance Screen

  5. Select option 3, Start Maintenance Mode for System Recovery, and press Enter. A screen similar to Figure 3 is shown.

    Figure 3: Maintenance Menu

  6. Enter 1, Access a Root Volume Group. A screen similar to Figure 4 is shown.

    Figure 4: Warning Message Window

  7. Enter a 0 and press Enter. A screen similar to Figure 5 is shown.

    Figure 5: Accessing a Volume Group

  8. Select the volume group whose logical volume information you want to display. This is important since rootvg will contain hd5 (the boot logical volume). Enter the number of the volume group and press Enter. A screen similar to Figure 6 is shown.

    Figure 6: Volume Group Information

  9. 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 is started and a system prompt is displayed.

  10. Take the appropriate measures to recover data or take additional action (such as using the bosboot command) to enable the system to boot normally.

2.5.2 Common Boot Time LED Error Codes and Recovery Actions

The most common boot problems and how to get your system up and running again are given in Table 8.

Table 8: Common Startup LEDs and Recovery Actions

2.6 Quiz