DM upgrade toolkit - how much space is enough?

How much space is really needed by witmupgrade to install the Unix OS agent for example? The install guide says 164Mb, but that doesn't apply for the migration toolkit...

There is installed agent space requirements, and there is also additional space required for the installation itself, which the install guide does not mention. During Unix OS agent installation using the witmupgrade command, an uncompressed .tar file will be pushed down by the upgrade toolkit on the agent machine to be used by the installation. In total, you will need at least 630Mb for the upgrade.

This is documented in section 5.3.2 of the Getting Started redbook.