IBM Support

Best Practice: Migrating to AIX 7.2

How To


This blog contained links to official IBM information plus Hints and Tips. Updated in March 2021.
This article is updated as more information and ideas become available.
Email your suggestions to the author - the email address at the end of the article.
This article does not include:
- "Line by line" and "screen by screen" details of the commands to update AIX.
- How to download the AIX 7.2 installation media from IBM ECC and prove you are entitled to do that (purchased AIX Support).
- The many different ways to boot off the various installation media or gain console access.


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Older AIX versions running on your Power Server.
Information on the reasons to upgrade from AIX 7.1 to AIX 7.2, can be found here:


AIX has the following type of improvements:
  • Updates for minor improvements
    • Yearly Technology Level (TL) improvements rounding up fixes and adds some new features 
    • During the year, Service Pack (SP) fixes bunches together for bugs, security, and performance tweaks
    • Updates are applied with AIX running and normally end with a mandatory reboot to activate the new AIX kernel.
  • Upgrades for major improvements - also called migrations
    • For larger release changes once every few years for major changes and new functions.
    • Example: AIX 5.3 to 6.1, AIX 6.1 to 7.1, AIX 7.1 to 72 and AIX 7.2 to 7.3 but note it is possible to migrate from AIX 6.1 straight to AIX 7.3. Check the Installation Release Notes.
    • Upgrades are applied AIX shut-down. Followed by booting from installation media to overwrite the rootvg disk or rebuilding to a new rootvg disk. Finally, a reboot to activate the new operating system.
      There is a pre-migration check script to run and any changed AIX configuration files are saved for the system admin person to double check after the upgrade.

The current release at the time this article is written AIX 7.2 TL5 SP1 or in full AIX release "7.2" Technology Level 5 Service Pack 1.
If you run the AIX command: 
$ oslevel -s
This shorthand means in full:
  1. "7200" = AIX 7.2,
  2. "05" = TL5,
  3. "01" = SP1 and
  4. "2038" means the year 2020 and week number 38 (middle of September).
Adding Technology Level and Service Pack updates can be performed with the operating system running. Some updates require an AIX reboot to activate the new kernel and new libraries. Typically the command is "smitty update_all".  Check the readme file instructions with each update.  These updates are downloaded from the IBM FixCentral website.
Upgrades from AIX 6.1 to AIX 7.2 require booting from new installation media found only on the IBM Electronic Software Support website (ESS) website.  To download the installation media requires proof of entitlement (PowerVM purchase) with a customer number and the server machine type model (MTM).
Note: AIX 7.2 upgrades (not updates) are also call migrations. They are called migrations as they require more effort than the smaller updates to install. For example,
  1. WARNING an outage is mandatory - the operating system is stopped - so application are stopped and user are not online.
  2. Read the AIX Migration documentation available on the download website. 
  3. Read the AIX 7.2 Release Notes for the Technology Level you are migrating too. 
  4. Downloading the AIX 7.2 installation media from IBM ECC.
  5. Run the pre_migration - this shell script can be extracted from the installation media.
  6. Take appropriate action from what you find out. For example
    • You might need to upgrade system firmware or HMC.
    • Check and adapters assigned to the AIX LPAR are supported in AIX 7.2.
    • Increase the size in CPU and memory of your Logical Partition (VM).
    • Increase the free space in AIX file systems.
    • Resize the boot volume or bootlist.
    • Upgrade the original AIX to a level supporting AIX 7.2 upgrades.
  7. Booting off the installation media for the new AIX 7.2 release.
  8. Follow the Migrating to AIX 7.2 documentation including:
    1. Installing with "migrate mode", copies over some core config files and settings from the previously running AIX release.
    2. This mode overwrites most of the AIX disk space in the rootvg volume group - like an installation. 
    3. Then, the "migrate" parts, brings over AIX settings, users, and packages from the original rootvg.
    4. Next, the enables the original networks and brings online all the original non-rootvg volume groups and disks
    5. Next, it mounts the file system in the original places and permissions.
    6. Finally, it reboots the newly configured operating system from disk.
  9. Upgrade to the latest AIX 7.2 Service Pack that might include fixes not on the AIX 7.2 Installation media and reboot again.
  10. Check the modification that the upgrade made, in the /var/adm/ras/config.diff file of the new operating system.
  11. System administrators then need to check the function of any RDBMS or application and the basics like backup, monitoring, security, and reporting.

Side note:
When AIX major release numbers there is an underlying cause due to functional changes to the operating system.
For example, covering three decades:
  • AIX 4.1 to AIX 4.2: added more CPUs, changed from single CPU to multiple Symmetric Multi-Processing (SMP) CPUs.
  • AIX 4.3 to AIX 5: added Logical Partitions (LPAR) also called virtual machines (VM) to run more than one Operating System on a single server.
  • AIX 5 to AIX 6: added the virtual I/O operations (network, disk, and optical) using the Power Hypervisor that uses a pair of Virtual I/O Servers (VIOS)
  • AIX 6 to AIX 7: Internal changes, performance-tuning framework, and superior "out-of-the-box" tuning settings.
  • AIX 7.1 to AIX 7.2: Functions like Live Kernel Update and Flash Cache and more.

Three key places for information
1) From the IBM Docs link for AIX 7.2 Release Notes:
image 8628
2) From the IBM Docs link for Migrating to AIX 7.2:  
image 8576
3) AIX Version 7.2 Installation and Migration Guide - a 450+ pages Manual covering both Installing and Migrating (starting on page 405).
image 8584

General information on AIX and manual pages:
 image 7978
The IBM top web page for AIX is: AIX TOP WEB PAGE with dozens of link to all the main topics.

Booting AIX from installation or migration Images (.iso or mksysb)
A quick reminder of the methods available for installing AIX from media:
  1. Internal to the Power server DVD drives - this method is largely historic and the industry move away from CD and DVD.
    Note: the AIX installation media size is roughly 4 GBs to 5 GBs, so CDROM is no longer works.
    New servers do not offer Internal DVD drives. See item 2.
  2. External to the Power server USB-based DVD drive. This DVD could be in a media bay or stand-only that uses the front of server USB socket.
  3. AIX based Network Installation Manager (NIM) to boot over the network - NIM could be using a mksysb or installation image.
  4. HMC-based Network Installation Manager on Linux (NIMOL), again over the network.
  5. PowerVM based virtual optical media that use the Virtual I/O Server (VIOS) from a .iso image.
  6. PowerVC might be an option for a .iso image on a disk to boot. (needs to be confirmed).
  7. Tape - rare these days.

Additional Information

Other content from Nigel Griffiths IBM (retired)

Document Location


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Document Information

Modified date:
09 June 2023