IBM Certification Study Guide AIX V4.3 System Support

3.2 Initialization Customization and Problem Determination

Generally, if you encounter a problem in the booting process, you receive a three-digit LED error code. In this section, several software problems are discussed along with their possible solutions.

3.2.1 Using the bootlist Command

You can change the way your system looks up devices to find its boot code. The bootlist command displays and alters the list of boot devices available to the system. The general syntax of the command is as follows:

bootlist [ { -m Mode } [ -r ] [  -o  ] [ [ -i ] | [ [ -f File ] [ Device [ Attr=Value ... ] ... ] ] ]

The most common flags used with bootlist command are given in Table 1.

Table 1: bootlist Command Flags

The bootlist command allows the user to display and alter the list of possible boot devices from which the system may be booted. When the system is booted, it will scan the devices in the list and attempt to boot from the first device it finds containing a boot image. This command supports the updating of the following:

Normal boot list: The normal list designates possible boot devices for when the system is booted in normal mode.
Service boot list: The service list designates possible boot devices for when the system is booted in service mode.
Previous boot device: This entry designates the last device from which the system booted. Some hardware platforms may attempt to boot from the previous boot device before looking for a boot device in one of the other lists.

Support of these boot lists varies from platform to platform, and some platforms do not have boot lists. When searching for a boot device, the system selects the first device in the list and determines if it is bootable, if no boot file system is detected on the first device, the system moves on to the next device in the list. As a result, the ordering of devices in the device list is extremely important.

In order to display a boot list (Version 4.2 or later) use the command:

# bootlist -m normal -o
fd0
cd0
hdisk0

If you want to make changes to your normal boot list use the command:

bootlist -m normal fd0 hdisk0 cd0

This will change the normal bootlist to indicate that when the system is booted, it will first attempt to boot from the floppy disk, if it cannot find a boot image in fd0, it will then look for hdisk0 to find the boot code, then it will search the CD-ROM. Otherwise, it will give an LED code and wait for user intervention.

3.2.2 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.

In order to access the system:

Turn the system key (if present) to the Service position or alternatively press F5 on PCI based system to boot from the tape/CD-ROM drive (during step 4).
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 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 on 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 9 is shown).

Figure 9: BOS Installation and Maintenance Screen
Select option 3 Start Maintenance Mode for System Recovery and press Enter=DO. A screen similar to the one in Figure 10 is shown.

Figure 10: Maintenance Menu
Enter 1, Access a Root Volume Group. A screen similar to the one in Figure 11 is shown.

Figure 11: Warning Message Window
Enter a 0 and press Enter=DO, a screen similar to Figure 12 is shown.

Figure 12: Accessing a Volume Group
Select the volume group whose logical volume information you want to display. This is important since rootvg will have hd5 that is the boot logical volume. Enter the number of the volume group and press Enter=DO. A screen similar to Figure 13 is shown.

Figure 13: Volume Group Information
Select one of the options from the Volume Group Information screen and press Enter. Each option does the following:

Choice 1
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
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.
Take appropriate measures to recover data or take action (such as using the bosboot command) to enable the system to boot normally.

3.2.3 Common Boot Time LEDs and Their Solution

The most common boot problems and how to get around to getting your system up and running again are given in Table 2.

Table 2: Common Startup LEDs and Solutions

3.2.3.1 lslv -m hd5 Example Output

The following is an example of the lslv -m hd5 command used when locating the boot device in single user mode.

# lslv -m hd5
hd5:N/A
LP    PP1  PV1               PP2  PV2               PP3  PV3
0001  0001 hdisk0
#

3.3 References