From Wiki

Hardware

• Minimum 40MB of disk space

OS

• CentOS 5.3+
• RedHat Enterprise 5.3+

We plan to add Debian and Ubuntu support soon.

Required software

• yum
• One or more of 1H software products
• Perl 5.8.0 or higher
• PostgreSQL 8.4.*
• gcc (needed to build Perl modules and will be automatically installed if not present on the server)