Cluster Deployment Options - AWS Elemental Delta

This is version 2.3 of the AWS Elemental Delta documentation. This is the latest version. For prior versions, see the Previous Versions section of AWS Elemental Delta Documentation.

Cluster Deployment Options

You can set up your cluster with leader and secondary nodes or you can also add egress-only nodes.

Important

It's assumed that you're using a load balancer with your AWS Elemental Delta cluster for outgoing traffic.

The load balancer is not controlled by AWS Elemental Delta and its setup is completely outside of Delta functionality. The load balancer can be set up in any suitable mode, for example, round robin mode.

The load balancer can use the Healthz feature of AWS Elemental Delta as described in Step G: Review the Cluster Management Configuration, to implement advanced balancing algorithms.

Leader and Secondary

Two nodes are set up, one as the leader and one as the secondary. You configure a load balancer on the outgoing side. This deployment is supported only in Delta 1.7 and later.


        Leader-secondary node cluster diagram.

Ingest

Both the leader node and the secondary node ingest content, but only the leader node processes and stores content. If the leader node fails, the secondary node takes over content processing and storage.

Egress

Both the leader and the secondary handle requests for output. The cluster is set up with a load balancer on the request side. Incoming requests for output hit the load balancer and are redirected to either node: the leader or the secondary.

Fail Over

If it is detected that the leader has failed (the heartbeat from the leader is not detected by the secondary), then the secondary declares itself the leader and takes over ingest tasks. It also continues handling requests for output.

For more detailed information about what happens during fail over, see the article Delta Cluster Fail Over Procedure.

Leader, Secondary and Egress Nodes

Several nodes are set up, one leader, one secondary, and one or more egress nodes. You configure a load balancer on the outgoing side. This deployment is supported only in AWS Elemental Delta 1.7 and later.


        Leader-secondary-egress node cluster diagram.

Ingest

Both the leader node and the secondary node ingest content, but only the leader node processes and stores content. If the leader node fails, the secondary node takes over content processing and storage.

Egress

Every node handles requests for output.

The cluster is set up with a load balancer on the request side. Incoming requests for output hit the load balancer and are redirected to any of the egress nodes.

Fail over

If it is detected that the leader has failed (the heartbeat from the leader is not detected by the secondary), then the secondary declares itself the leader and takes over ingest tasks. It also continues handling requests for output. Egress nodes are never eligible to become leader.

If an egress node has failed, it simply becomes ineligible for handling requests for output. There is no fail over.