Informix Replication / Disaster Recovery
SDS (Shared Disk Secondary)
SDS shares the disk space with the primary. SDS servers are quick to add and allow you to scale out your workload.
HDR (High Availability Data Replication)
HDR consists of a pair of servers (Primary and HDR) to replicate transactions from the Primary to HDR server which can become the Primary in case of a failure of the Primary.
RSS (Remote Standalone Secondary)
Like HDR but is asynchronous. Also you can have "X" number of RSS servers in remote location and is less sensitive to latency.
ER (Enterprise Replication
ER allows you to replicate at the table/column level to many nodes. It creates a network of topology of root, leaf, and no-root, no-leaf nodes.
Sharding
With Sharding, you can horizontally partition a single table across multiple database servers in a shard cluster.