What’s the product configurations?

Configurations for availability, durability, and resilience.

Depending on the number of sites in the ECS system, different data protection schemes can increase availability and balance the data protection requirements against performance. ECS uses the replication group to configure data protection schemes.

Local Protection

Data is protected locally by using triple mirroring and erasure coding which provides resilience against disk and node failures, but not against site failure.

Full Copy Protection

When a replication group is enabled with the Replicate to All Sites property, the replication group makes a full readable copy of all objects to all sites within the replication group. Having full readable copies of objects on all VDCs in the replication group provides data durability and improves local performance at all sites at the cost of storage efficiency.

Geo-Active

Geo-Active is the default ECS configuration. When a replication group is configured as Geo-Active, data is replicated to federated sites and can be accessed from all sites with strong consistency. If you have two sites, full copies of data chunks are copied to the other site. If you have three or more sites, the replicated chunks are combined (XOR'ed) to provide increased storage efficiency. When data is accessed from a site that is not the owner of the data, until that data is cached at the non-owner site, the access time increases. Similarly, if the owner site that contains the primary copy of the data fails, and if you have a global load balancer that directs requests to a non-owner site, the non-owner site must recreate the data from XOR'ed chunks, and the access time increases.

Geo-Passive

The Geo-Passive configuration always includes exactly three sites and is available where you have at least three sites. In this configuration, two sites are active. The third site is passive and is a replication target. You can designate a specific site as the backup site and achieve the storage efficiency (2.0 times storage overhead) of three sites. The storage efficiency is the same as the Geo-Active three-site configuration. In the Geo-Passive configuration, all replication data chunks are sent to the passive site and XOR operations occur only at the passive site. In a Geo-Active configuration, the XOR operations occur at all sites. If all sites are on-premise, any of the three sites can be the replication target. An important use case for the Geo-Passive configuration is when the passive site is hosted by a third party and the hosted site is selected as the replication target. This configuration can be modified by using the ECS Management REST API to select an on-premise site as the replication target.