In the weekend I had to migrate a Domino environment from 9.0.1.x to the latest release. What I could see during the migration:

Backup the NOTES.INI before you run the “UPDDOMSVR” command (!)
Maybe it was in this environment but after running the UPDDOMSVR the NOTES.INI only contained 3 lines and all the other informations have been gone. Therefore we had to restore the NOTES.INI from the backup we took before

Set appropriate environment variable
ADDENVVAR ENVVAR(DOMINO_INSTALL_TYPE) VALUE(0) – Messaging
ADDENVVAR ENVVAR(DOMINO_INSTALL_TYPE) VALUE(1) – Utility
ADDENVVAR ENVVAR(DOMINO_INSTALL_TYPE) VALUE(2) – Enterprise

Difference on IBM iSeries from Linux/Windows
On the iSeries you do not need to install 11.0.1 and afterwards FP2 because the installer is a “Full Install Kit” ! Therefore you either extract the Domino_1101FP2_IBMi.exe and run the OS400Install.exe which does all the work for you ( upload of the requested files and the installation ) or you go through the manual installation ( very well documented here ).

Upgrading the databases to ODS53
Also on IBM iSeries you can run the compact in offline mode. I already wrote it down in this blog post.