High Availability

GitLab (fewer requirements)
GitLab (has true HA)
Minimum hardware requirements: 4 vCPU and 4 GB RAM support up to 500 users. No specific recommendation for disk size.
GitLab high availability is achieved by having full redundancy of all components and automatic failover (i.e. if a component fails, its counterpart automatically takes over). The parts include: ā€¢ Omnibus installation with database redundancy and automatic failover (PostgreSQL and Redis) failover (Premium).
Supporting up to 3000 users, requires 8 vCPUs, 48 GB RAM, 300 GB attached storage, 200 GB root storage.
There is no truly HA configuration of GitHub.