Installing OpenMRSPrerequisites setup
The hardware required depends on the size of your implementation. For small implementations, OpenMRS can be run on just about any desktop or laptop.
...
AMPATH is supporting an OpenMRS instance with over 250,000 patients with two 2.26 GHz quad processors, 16 GB of memory, and 500 GB of disk space with RAID and appropriate backup facilities.
Profiles of Real-World Implemented System Specifications
You can view profiles of real-world implemented systems here.