1. Introduction In this how-to, we will present you how to size your servers according to the number of users in your organization that will use OpenOTP. 2. With an external directory (AD, Novell…) 2.1 Recommendations for 500 Users 1 dedicated server or Virtual machine with Linux (2 for High Availability). Server configuration: 1.5GHz processor (4 cores). 4GB RAM memory. 15GB disk space for installation files, log files and DB.