Software upgrade or replacement

Use this information to understand special considerations of the server and its software when you upgrade or replace a release.

• Supported releases for i5/OS (OS/400) upgrades
  Upgrades to current releases require that you be at a certain level of software. This information shows the supported combinations for source and current target releases.
• Installation and IBM-supplied objects
  When you replace your software with the new release, by default the server keeps changes that you made to some IBM-supplied objects.
• Compressed objects and storage space
  All of the licensed programs and some objects of the operating system ship in a compressed form. This requires less storage space on your server. The server decompresses objects according to certain criteria, which could affect the performance of the server.
• Files that the server deletes during installation
  If you have created logical files over IBM-supplied physical files in QSYS, the logical files will be deleted during the installation process.