14.2 Processor Dependent Code | HP Certified: HP-UX System Administration

The boot procedure for all HP-9000 systems is controlled by program code, PDC, that resides on the ROM installed inside the system. The PDC is different for different computers (that is why its name is processor dependent). PDC is executed after the system is reset or turned on. It performs self-tests and then tests hardware attached to the system. After thoroughly scanning the memory, it initializes the console and copies the console path to the memory. It copies the boot path and autoboot flag into memory. If the autoboot is disabled, it displays a menu of commands. If the autoboot is enabled, it displays a message showing that the system is going to start the autoboot process and gives you the option to interrupt this process by pressing a key within 10 seconds. If you press a key within 10 seconds, you get the PDC menu; otherwise , the system starts booting from the primary boot path.

PDC is an important part, where you perform system administration tasks to specify primary and alternate boot devices. You can display hardware paths and search boot devices attached to the system. You can also use PDC to boot the system from a device other than primary or secondary boot devices. On V-Class machines, PDC can also be used to boot into single- user mode.

PDC Menus

You get PDC menus by interrupting the boot process by pressing a key when a message like the following is displayed.

 Processor is starting the autoboot process. To discontinue, press any key within 10 seconds.

PDC menus may differ on servers and workstations slightly, but most of the commands are the same on all systems. A typical PDC menu looks likes the following.

 ---------------------- Main Menu -------------------------- Command                       Description -------                       ----------- BOot [PRIALT<path>]         Boot from specified path PAth [PRIALT<path>]         Display or modify a path SEArch [DisplayIPL] [<path>] Search for boot device COnfiguration menu            Displays or sets boot values INformation menu              Displays hardware information SERvice menu                  Displays service commands Help [<menu><command>]       Displays help for menu or cmd RESET                         Restart the system ---------- Main Menu: Enter command or menu >

You can use any of these commands; most of the arguments are optional. For example, using the boot command without any arguments will start the autoboot process. If you want to boot from the alternate boot device, you can use the boot alt command. In case you need to boot the system from a device that is neither a primary nor an alternate boot device (such as booting from CD-ROM when installing HP-UX), you can specify the device name as an argument to the boot command.

All of these commands can be abbreviated. The capital letters in the start of each command show the command abbreviation. For example, you can use " bo " instead of boot and " sea " instead of the search command. Help on commands is also available with the Help command.

Searching Boot Devices

You need to search for boot devices if you don't know the exact name of a device for boot purposes. This is often required when installing a new system. The search command shows all disk drives, CD-ROM devices, and tape drives attached to the system. Output of the search command is like the one given here.

 Main Menu: Enter command or menu > search Searching for potential boot device(s) This may take several minutes. To discontinue search, press any key (termination may not be immediate) Path Number  Device Path (dec)  Device Type -----------  -----------------  ----------- P0           10/0/6             Random Access Media P1           10/0/5             Random Access Media P2           10/0/4             Random Access Media P3           10/0/3             Random Access Media P4           10/0/2             Random Access Media P5           10/0/1             Random Access Media P6           10/4/4.2           Toshiba CD-ROM Device P7           10/4/4.1           Sequential Access Media

Random Access Media shows disks attached to the system, and Sequential Access Media is for tape drives. You can also see a line for a CD-ROM drive. Sometimes you will see Random Access Media in place of the CD-ROM drive. In that case, you have to make a guess which device shows the CD-ROM if you are not familiar with your HP system hardware configuration.

To boot from a particular device, you can use its path number or device path. For example, to boot from a CD-ROM, you can use any of the boot P6 or boot 10/4/4.2 commands.

Booting from an Alternate Disk

Many people use mirrored disks in servers for redundancy and reliability. In a mirror disk configuration, two disks have exactly the same data. Boot devices can also be mirrored so that in case one disk fails to boot the system, it may use the alternate one for the boot process.

To configure an alternate boot device, you can use the configure command. To manually boot from the alternate disk device, use the boot alt command.

Stable Storage

Stable storage is nonvolatile memory where your system stores information about the following.

primary boot path
alternate boot path
console
autoboot
autosearch

This information is used by PDC. You can change this information using the configure command. Autoboot and autosearch are either on or off.

Booting in Single-User Mode

On V-Class machines, you can use PDC to boot the system in single-user mode for maintenance purposes. The PDC command used for this purpose is:

 Main Menu: Enter command or menu >  boot pri -is

On other machines, you can stop the boot process and use ISL to boot into single-user mode as shown here.

 Main Menu: Enter command or menu >  boot pri  Interact with ISL (Y or N)?>  Y

When you get the ISL prompt, use the following command to boot into single-user mode.

 ISL>  hpux -is

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