In a region, each availability zone is isolated from the other availability zones to prevent reproducing failure or outage across zone boundaries.

Using multiple availability zones provides high availability through redundancy.

Table 1. Characteristics of Availability Zones

Availability Zone Characteristic

Description

Outage prevention

You avoid outages and improve SLAs. An outage that is caused by external factors, such as power supply, cooling, and physical integrity, affects only one zone. These factors do not cause outage in other zones except in the case of major disasters.

Reliability

Each availability zone runs on its own physically distinct, independent infrastructure, and is engineered to be highly reliable. Each zone should have independent power, cooling, network, and security. Do not share common points of failures in a physical data center, like generators and cooling equipment, across availability zones. Additionally, these zones should be physically separate so that even uncommon disasters affect only one zone.

Availability zones are either two distinct data centers in a metro distance, or two safety or fire sectors (data halls) in the same large-scale data center.

Distance between zones

Multiple availability zones belong to a single region. The physical distance between availability zones is short enough to offer low, single-digit latency (less than 5 ms) and large bandwidth (10 Gbps) between the zones.

You can operate workloads across multiple availability zones in the same region as if they were part of a single virtual data center. This architecture supports high availability that is suitable for mission critical applications.

If the distance between two locations of equipment becomes too large, these locations can no longer function as two availability zones in the same region and must be treated as separate regions.