DHIS2 is a database intensive application and requires that your server has an appropriate amount of RAM, number of CPU cores and a fast disk. These recommendations should be considered as rules-of-thumb and not exact measures. DHIS2 scales linearly on the amount of RAM and number of CPU cores so the more you can afford, the better the application will perform.
RAM: At least 1 GB memory per 1 million captured data records per month or per 1000 concurrent users. At least 4 GB for a small instance, 12 GB for a medium instance.
CPU cores: 4 CPU cores for a small instance, 8 CPU cores for a medium or large instance.
Disk: Ideally use an SSD. Otherwise use a 7200 rpm disk. Minimum read speed is 150 Mb/s, 200 Mb/s is good, 350 Mb/s or better is ideal. In terms of disk space, at least 60 GB is reccomended, but will depend entirely on the amount of data which is contained in the data value tables. Analytics tables require a significant amount of disk space. Plan ahead and ensure that your server can be upgraded with more disk space as it becomes needed.