This little blog post will first explain how to check the previous AIX Technology Level (TL) which was installed before an upgrade and then we will venture into how to rollback the AIX TL, or Service Pack, to a previous version.

After an upgrade has been performed you can only check the Technology Level (TL) that was installed previously if the TL fileset, or service pack, still exist on the system and this will be reported by the oslevel command with the –qs option, like so:

oslevel –qs

This little blog post will first explain how to check the previous AIX Technology Level (TL) which was installed before an upgrade and then we will venture into how to rollback the AIX TL, or Service Pack, to a previous version.

After an upgrade has been performed you can only check the Technology Level (TL) that was installed previously if the TL fileset, or service pack, still exist on the system and this will be reported by the oslevel command with the –qs option, like so:

oslevel –qs

Also you could check the SMITTY or SUMA log file to see what the TL was before the upgrade was started. If you’re wishing to see the fixes which are currently on the system for the TL you are at you can use the following command:

instfix –i | grep TL

And you can use the lppchk command to check system consistency like so:

lppchk -v

Now to the fun part… Rolling back the TL. A word of warning first, I would not recommend rolling back a service pack or TL since it is not well supported due to the fact that some software on the system could rely on specific fixes or a specific TL to be installed for it to operate properly. You will find some commands below, specifically instfix and lppchk which you can use to check the dependencies of software on your system.

When upgrading a Technology Level (TL) it is recommended to use mksysb to create an image of the root volume group then install the TL in applied mode so that if a rollback needs to be done, the state of your system previously is not lost or miss-configured. When installing a TL, fixpack or service pack you should do so in applied mode then the installation will not be committed until the system is rebooted so at any point you can go back into the smitty menu and “Reject Applied Software Updates”.

But let’s move on to the actual rollback procedure. Let’s start by simply downloading the specific fileset from the following URL:

http://www14.software.ibm.com/webapp/set2/abl/bundle?release=53

Then issue the installation commands in the following fashion:

inutoc

Replace with the location of where you downloaded the fileset to. Then to install all updates in the fileset issue the following command, remember to make sure your installing in APPLIED mode so that you can remove anything before reboot and not have any issues:

smit update_all

You can also use SUMA to automate this procedure, please reference the following informational URL:

http://www-128.ibm.com/developerworks/aix/library/au-updateaix.html

You may now wish to check if all your software is functioning as expected and that the older fileset is causing no inconsistency.

Enjoy,
Josh Diakun
http://www.joshd.ca