What are prerequisites? Prerequisites are what you, your machine, and your distribution require before you will be able to successfully install or use Lotus Domino R5. The required prerequisites come straight from Notes, Domino and Domino Designer RELEASE NOTES, Chapter 2. The suggested prerequisites come from experience. For your convenience, I've divided them into hardware and software requirements.
x86 compatible (for example, Intel, AMD, or Cyrix). I've successfully installed Domino Application Server 5.08 on an AMD Duron 800, Intel Celeron 400 and Enterprise Server 5.09a on an AMD Athlon 1000. Your experiences with other x86 processors would be appreciated.
I've found 128 MB of RAM is enough to run a single Domino Application Server and test out your applications. In my case, I was working with a AMD Duron 800 processor and 128 MB of RAM. However, more memory is recommended if you're putting your application into production or running multiple services. Swap file should be 3 times the physical RAM or greater.
For a typical non-partioned installation of the Lotus Domino R5 Application Server, you will need about 300 MB of free disk space.