This chapter describes how to install the Base Operating System (BOS) using a system backup image, also called a mksysb image. You can use a system backup to restore a corrupted operating system. But installing a system from a backup can also reduce (or even eliminate) repetitive installation and configuration tasks. For example, you can use a backup to transfer optional software installed on the source system (the machine from which you created the backup copy), in addition to the basic operating system. Also, the backup image can transfer many user configuration settings to the target system (a different machine on which you are installing the system backup).
The procedure you use to install from a system backup depends on whether you are installing on the source or target system and which interface you want to use:
You can install a system from a backup image that is stored on tape or CD, or in a file. If you want to install a backup stored in a directory on your network installation server, refer to Using a mksysb Image to Install the Base Operating System (BOS) on a NIM Client (mksysb Install).
The procedures to install from backup operate either in prompted or nonprompted mode, depending on conditions set in the /bosinst.data file and on compatibility between the backup image and the installed machine. See Customized BOS Installations for information on how to modify the bosinst.data file to preset installation parameters when you create a system backup.
When installing the backup image, the system checks whether the target system has enough disk space to create all the logical volumes stored on the backup. If there is enough space, the entire backup is recovered. Otherwise, the installation halts and the system prompts you to choose additional destination hard disks.
File systems are created on the target system at the same size as they were on the source system, unless the backup image was created with SHRINK set to yes in the image.data file (or you set it to yes in the BOS Install menus). An exception is the /tmp directory, which can be increased to allocate enough space for the bosboot command. For information about setting variables, refer to the image.data file in AIX 5L Version 5.2 Files Reference.
After installing the backup image, the installation program reconfigures the Object Data Manager (ODM) on the target system. If the target system does not have exactly the same hardware configuration as the source system, the program might modify device attributes in the following target system files:
The settings in the bootlist of the target system are not restored. After a system backup restore, the bootlist is reset to the primary boot device.
With a mksysb image, you can clone one system image onto multiple target systems. However, the target systems might not contain the same hardware devices or adapters, or require the same kernel (uniprocessor or microprocessor) as the source system. Beginning in AIX 5.2, all devices and kernels are automatically installed during a BOS installation. So, when you create a system backup, the mksysb image contains all the device and kernel support. For example, you can create a system backup from System_A and install System_A's mksysb image onto System_B without having to use product media to boot System_B. For more information on installing all devices and kernels, see Install All Device and Kernel Support Before the Backup is Created.
Beginning in AIX 5.2, if you are performing a clone installation, device information will not be restored to the target system. During a clone installation, the BOS installation process checks to see if the mksysb image is from the system you are trying to install. If the target system and the mksysb image are different, then device is not recovered.
If the source system does not have the correct passwords and network information, you can make modifications on the target system now. Also, some products (such as graPHIGS) ship device-specific files. If your graphics adapter is different on the target system, verify that the device-specific filesets for graphics-related LPPs are installed.
You can use Web-based System Manager or SMIT to restore an operating system onto the same machine from which you created the backup. For either interface, the following conditions must be met before beginning the procedure:
| CD or DVD | BOS CDs, created in one of the following ways:
|
| Tape | BOS tapes, created in one of the following ways:
|
| Network | The path to your backup image file. For information about installing a backup across a network, refer to Using a mksysb Image to Install the Base Operating System (BOS) on a NIM Client (mksysb Install). |
Note: Before you begin, select the tape or CD/DVD-ROM drive as the primary boot device. For additional information, refer to the section in your hardware documentation that discusses system management services.
To use Web-based System Manager:
If you choose this option, your machine must either be a configured NIM client, or have access to a NIM environment. If your machine is not a NIM client, the Reinstall Base Operating System wizard leads you through the process. For more information on setting up a NIM environment, see Using Installation Images to Install the Base Operating System (BOS) on a NIM Client.
To use SMIT:
shutdown -F
Turning on the external devices first is necessary so that the system unit can identify them during the startup (boot) process.
You might find that on certain tape drive units, the tape drive door does not open while the system is turned off. If you have this problem, use the following procedure:
Note: If your terminal is an IBM 3151, 3161, or 3164, press the Ctrl+Setup keys to display the Setup Menu and follow the onscreen 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.
| Communication Options | |
|---|---|
| Option | Setting |
| 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 |
| Keyboard and Display Options | |
|---|---|
| Option | Setting |
| 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: You can boot from production media (tape or CD) if your backup media fails to boot. The initial Welcome screen includes an option to enter a maintenance mode in which you can continue the installation from your backup media. Refer to Troubleshooting an Installation from a System Backup for more information.
If you have more than one console, each terminal and directly attached display device (or console) might 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 only 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.
Note: If the bosinst.data file lists a valid display device for the CONSOLE variable, you do not manually choose a system console. Read Customized BOS Installations for more information about the bosinst.data file.
| PROMPT = no | Nonprompted Installation. This installation method is used if the backup image is configured to install automatically, without having to respond to the installation program. Go to step 8. |
| PROMPT = yes | Prompted Installation. This installation method is used if you need to use menu prompts to install the backup image. Also, use this installation method if a nonprompted installation halts and the Welcome to Base Operating System Installation and Maintenance screen displays. Go to step 9. |
Note: If the backup image holds source system-configuration information that is incompatible with the target system, the nonprompted installation stops and a prompted installation begins.
The Installing Base Operating System screen displays before the installation starts. The nonprompted installation pauses for approximately five seconds before beginning. After this time, the non-prompted installation continues to completion.
However, if you decide to interrupt the automatic installation and start a prompted session, type 000 (three zeros) at the terminal and follow the remaining steps in this procedure.
Note: You can view Help information at each screen of this installation process by typing 88.
Choose the Change/Show Installation Settings and Install option.
To accept the settings and begin the installation, skip to step 16.
To change the settings, continue with step 11.
Type the number and press Enter for each disk you choose. Type the number of a selected disk to deselect it. You can select more than one disk.
Note: You can also specify a supplemental disk by typing 66 and pressing the Enter key for the Disks not known to Base Operating System Installation option. This option opens a new menu that prompts for a device support media for the supplemental disk. BOS installation configures the system for the disk and then returns to the Change Disk(s) Where You Want to Install screen.
The screen that displays after you press the Enter key is dependent on the availability of map files for all of the selected disks. The criteria for this is as follows:
To preserve the placement of files during a future restoration of the backup, you can create map files before backing up a system. Map files, stored in the /tmp/vgdata/rootvg directory, match the physical partitions on a drive to its logical partitions. Create map files either with the SMIT Backup the System menu, using Web-based System Manager, or using the -m option when you run the mksysb command.
For more information about map files, see Using Map Files for Precise Allocation in AIX 5L Version 5.2 System Management Concepts: Operating System and Devices.
When you complete this choice, BOS installation returns to the System Backup Installation and Settings screen.
File systems on your backup image might be larger than required for the installed files. Press the 2 key to toggle the Shrink File Systems option between Yes and No in the System Backup Installation and Settings screen. The default setting is No.
Note: Shrinking the file system disables the use of maps.