As hardware ages, locating specific legacy software versions like 11.20 can become challenging. This document outlines the features of this version and the proper channels for acquisition.
Some IT professionals have uploaded verified, clean copies to archive.org. Search "DS Storage Manager 11.20 Archive.org". (MD5/SHA1) against known values from IBM documentation. ibm ds storage manager 11.20 download
Install the "Client" for remote management or the "Station" for local management. As hardware ages, locating specific legacy software versions