Installing the Base Operating System

There are multiple ways to install the AIX® base operating system.

The Base Operating System (BOS) installation program first restores the run time bos image, then installs the appropriate filesets, depending on your selections. The installation program automatically installs required message filesets, according to the language you choose.

If you require a minimal install, change the selections for the Graphics Software and the System Management Client Software to no in the More Options menu of the BOS menus. These options are the GRAPHICS_BUNDLE and SYSTEM_MGMT_CLIENT_BUNDLE fields in a Network Install bosinst_data resource. The Enable System Backups to install any system field is set to yes. This field is the ALL_DEVICES_KERNELS field in your bosinst_data resource. Performing a minimal install is only applicable for New and Complete Overwrite or Preservation installation methods.

If you are reinstalling on an older system, the DVD media can only be used to boot or reinstall on 64-bit systems. To determine if your system is a 32-bit system or a 64-bit system, run the prtconf command with the -c flag.

AIX Base media and AIX NIM lpp_source created from Base media, include updates for bos.rte* software. These packages are at the same V.R.M.F (version.release.modification.fix) levels as the base operating system that is restored during an operating system installation. They are also present on the media for the cases where the Base media is used to upgrade a system already at the same version and release level; to a new modification or fix level. It is recommended that you use either update media (or downloaded technology levels or service packs) to do upgrades. To support upgrading a WPAR (Workload Partition) that is moving from one system to another, the root parts of these updates are restored onto the system during an operating system installation. The data is restored into /usr/lpp/bos/<bos.rte_software_name>/V.R.M.F/inst_root directories. A new command, /usr/sbin/cp_bos_updates, is called, and is also available for users to run from the command line. If a system is installed from an lpp_source without the bos.rte* updates, running cp_bos_updates manually is required to support upgrading WPARs. This command allows support for WPAR Mobility, and the restwpar to restore a WPAR to a new system.

If you are performing a BOS installation or a mksysb installation on a disk with multiple ports such as Multipath I/O (MPIO), the port must remain active for the duration of the install.

Note: Before applying a Technology Level (TL), you must always create a backup and plan on restoring that backup if you need to rollback to your previous level. You can also use the alt_disk_install or multibos options as a way to get back to your previous level. Since TL updates cannot be rejected you must always commit the updates.

For more information about the installation options, refer to bos_install_more_options.html.

The following installation methods are available on AIX:

New and Complete Overwrite
This method installs AIX 7.3 on a new machine or completely overwrites any BOS version that exists on your system.

For instructions on installing AIX 7.3 on a new machine or to completely overwrite the BOS on an existing machine, refer to Installing new and complete BOS overwrite or preservation.

Preservation
This method replaces an earlier version of the BOS but retains the root volume group, the user-created logical volumes, and the /home file system. The system file systems /usr, /var, /tmp, /opt, and / (root) are overwritten. Product (application) files and configuration data stored in these file systems will be lost. Information stored in other non-system file systems will be preserved.

For instructions on preserving the user-defined structure of an existing BOS, refer to Installing new and complete BOS overwrite or preservation.

Migration
This method upgrades from earlier versions of the AIX BOS to AIX 7.3 (see the release notes for restrictions). The migration installation method is used to upgrade from an existing version or release of AIX to a later version or release of AIX. A migration installation preserves most file systems, including the root volume group, logical volumes, and system configuration files. It overwrites the /tmp file system.

For instructions on migrating an existing version or release of AIX to a later version or release of AIX, refer to Migrating AIX.

The following table shows the differences in the installation steps among the installation methods.
Table 1. AIX BOS Installation Methods
Installation Steps New and Complete Overwrite Preservation Migration
Create rootvg Yes No No
Create file system /, /usr, /var Yes Yes No
Create file system /var/adm/ras/livedump. If this file system does not exist, it is created during any method of installation. Yes Yes, if not present* Yes, if not present*
Create file system /home Yes No No
Save Configuration No No Yes
Restore BOS Yes Yes Yes
Install Additional Filesets Yes Yes Yes
Restore Configuration No No Yes
* The livedump file system is only created during preservation or migration installations if it does not exist. You can modify the file system by using a customized bosinst.data file with a livedump stanza.
Note: If you perform a migration or preservation type of installation on an existing rootvg that is running a multibos instance of AIX (bos_* logical volume names), the multibos instance is accepted as a rootvg, and after the installation is complete, logical volume names are changed to the original names. It applies to both preservation and migration type of installations.