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## Failover and Switchover Operations

Optimal use of available physical datacenters is achieved by deploying your store across multiple zones. This provides fault isolation as each zone has a copy of your complete store, including a copy of all the shards. With this configuration, when a zone fails, write availability is automatically reestablished as long as quorum is maintained.

Note:

To achieve other levels of fault isolation, best practices for data center design should be applied. For example, site location, building selection, floor layout, mechanical design, electrical system design, modularity, etc.

However, if quorum is lost, manual procedures such as failovers can be used instead to recover from zone failures. For more information on quorum, see Concepts Guide.

A failover is typically performed when the primary zone fails or has become unreachable and one of the secondary zones is transitioned to take over the primary role. Failover can also be performed to reduce the quorum to the available primary zones. Failover may or may not result in data loss.

Switchovers can be used after performing a failover (to restore the original configuration) or for planned maintenance.

A switchover is typically a role reversal between a primary zone and one of the secondary zones of the store. A switchover can also be performed to convert one or more zones to another type for maintenance purposes. Switchover requires quorum and guarantees no data loss. It is typically done for planned maintenance of the primary system.

In this chapter, we explain how failover and switchover operations are performed.

Note:

Arbiters are not currently supported during failover and switchover operations.