TH 04 ‐ Difference between Region, AD, and FD - gautam-amitesh/OCI GitHub Wiki

Region

The country or the city a cloud provider choose to create a data center is called region.

AD

AD stands for Availability Domain which is just a data center where servers are stored. It is recommended to have atleast 1 AD and maximum of 3 AD, it is a fail safe mechanism. When creating data center in a country or city cloud provider choose locations where to store servers which is upto 3 locations and minimum of 1 location.

Criteria for AD

  1. far distinct locations
  2. different power supply for every location
  3. secure place(natural and man-made threat)
  4. best networking

Exception

Some times cloud provider want to build single AD due to selection criteria, area availability, and userbase.

FD

FD stands for Fault Domain which is just server rooms, every AD have 3 FD to create a fail safe mechanism such that if one server have problem other servers can still perform.