Deciding Between FTL Stores and File-Based Stores

When making the decision between FTL stores and file-based stores for a fault-tolerant EMS server deployment, there are three main criteria to consider.

Availability of Shared Storage

If a shared storage mechanism that meets the Support Criteria for shared state is available, file-based stores would be the preferred option. However, when such a storage mechanism is not available, or does not provide reasonable I/O speeds, FTL stores offer a strong, performant alternative that fulfills all the data persistence and replication requirements needed for EMS fault-tolerance. A good example of this is in cloud-based deployments, where shared storage may not be an option, or may be prohibitively slow even when available. FTL stores would be able to leverage the more performant storage options offered by the cloud service provider to support a fault-tolerant deployment. Additionally, a cloud-based deployment of FTL stores would also be capable of deploying across multiple availability zones to provide a level of redundancy and availability that may not be achievable using shared storage.

Failover Time

For deployments where a large amount of backlogged persistent message data is expected, FTL stores can provide faster recovery time than file-based stores in most fault-tolerant failover scenarios. With smaller pending message backlogs, the fault-tolerant failover recovery times for both store types will be comparable.

Disaster Recovery

Another criteria to consider is whether disaster recovery is important for the deployment. When using FTL stores, EMS is able to leverage its integration with FTL to provide disaster recovery as an in-built feature. The EMS server does not have this capability when using file-based stores.