Introduction to ECS site outage and recovery

ECS is designed to provide protection when a site outage occurs due to a disaster or other problem that causes a site to go offline or become disconnected from the other sites in a geo-federated deployment.

Site outages can be classified as a temporary site outage (TSO) or a permanent site outage (PSO). A TSO is a failure of the WAN connection between two sites, or a temporary failure of an entire site (for example, a power failure). A site can be brought back online after a TSO. ECS can detect and automatically handle these types of temporary site failures.

A PSO is when an entire site becomes permanently unrecoverable, such as when a disaster occurs. In this case, the System Administrator must permanently fail over the site from the federation to initiate failover processing, as described in #GUID-042D2322-0A4B-474F-826F-E58BC3D6FBA8.

TSO and PSO behavior is described in the following topics:

• TSO behavior
• TSO considerations
• NFS file system access during a TSO
• PSO behavior

ECS recovery and data balancing behavior is described in these topics:

• Recovery on disk and node failures
• Data rebalancing after adding new nodes