PubSub+ Cache Redundancy and Network Deployments
This section discusses some best practices for deploying PubSub+ Cache within a network with Solace PubSub+ event brokers, including:
- Implementing PubSub+ Cache redundancy on a single event broker
- Using a Distributed Cache with a fault‑tolerant, redundant pair of event brokers
- Using a Distributed Cache in conjunction with routers installed in primary and backup data-centers for data center redundancy
- Using Global Caching to extend the caching solution to a multi-region deployment
- Recommended Multiple-Node Routing topologies for these various network deployments of PubSub+ Cache
In general, fault tolerant PubSub+ Cache deployments are achieved in a Dynamic Message Routing (DMR) or Multi-Node Routing (MNR) event mesh by ensuring every cache cluster contains multiple cache instances. Each instance connects to a different PubSub+ event broker within the mesh. The approach ensures that no single failure (be it network disruption, PubSub+ broker service disruption, or failure of a cache instance) will affect the ability of the cache to continue both caching messages and servicing cache requests.
When setting up PubSub+ Cache within a network of event brokers, many deployment combinations and variations are possible. This section describes the most common deployment models. However, when planning a complex multi‑site deployment, Solace Professional Services should be engaged to assist with the network architecture design, and to make recommendations on the best model for specific use cases.
An example of this deployment model is illustrated below. Any one (but only one) of the PubSub+ brokers within the event mesh shown may be the designated cache manager, and a failure affecting that broker will not disrupt caching service for that cluster. The remaining brokers and cache instances will continue to function while connectivity to the cache manager is restored.
Publishers, subscribers, and optionally cache instances may use host-lists to identify their primary and secondary PubSub+ brokers in the mesh. This allows connections to be immediately re-established with the event mesh should the primary broker fail or become unreachable.
It's assumed that the reader of this section is already familiar with the basic concepts and configuration of PubSub+ Cache, Distributed Caches, Global Caching, router redundancy, Multiple-Node Routing, Replication, and Config‑Sync.