Erasure coding is a set of algorithms that allows the reconstruction of missing data from a set of original data. In theory, erasure coding uses less capacity with similar durability characteristics as replicas. From an application perspective, erasure coding support is transparent. Object Storage (swift) implements erasure coding as a Storage Policy. See Storage Policies for more details.
There is no external API related to erasure coding. Create a container using a Storage Policy; the interaction with the cluster is the same as any other durability policy. Because support implements as a Storage Policy, you can isolate all storage devices that associate with your cluster’s erasure coding capability. It is entirely possible to share devices between storage policies, but for erasure coding it may make more sense to use not only separate devices but possibly even entire nodes dedicated for erasure coding.