Applications to the Shutdown Process
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.
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
In order to access the system:
- 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.
- Insert Volume 1 of the installation media into the tape or CD-ROM drive and
power the system unit off.
- 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).
- 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
- Select option 3, Start Maintenance Mode for System Recovery, and
press Enter. A screen similar to Figure 3 is shown.
Figure 3: Maintenance Menu
- Enter 1, Access a Root Volume Group. A
screen similar to Figure 4 is shown.
Figure 4: Warning Message Window
- Enter a 0 and press Enter. A screen similar to
Figure 5 is shown.
Figure 5: Accessing a Volume Group
- 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
- Select one of the options from the Volume Group Information screen and
press Enter. Each option does the following:
- 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
- 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
- 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.
- Take the appropriate measures to recover data or take additional action
(such as using the bosboot command) to enable the system to boot
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