added scaling talk

docs/source/01-04-planning-architecture.md

@@ -19,3 +19,38 @@ Application servers: c4.xlarge (16 VM nginx + Talk VM machine pairs)
 Mongo nodes: 3x c3.medium (large db cluster, 1 master, 2 read replicas)
 
 If you need help with Talk performance or want custom scaling help or recommendations, let us know by logging a ticket and one of our engineers will get in touch with you: https://support.coralproject.net
+
+## How to Scale Talk Components
+### Scaling the Talk Application
+
+In addition to scaling by adding additional app servers, Talk as a server component can flex to various roles. Depending on the desired configuration the roles can be split up to ensure high availability, and best matching to underlying host resources. 
+
+There are three components to the Talk application that can be served independently or in combination on a single thread: API Server, WebSockets, and Jobs
+
+![ServerArchitectureDiagram](/talk/images/ServerArch.png)
+
+In the diagram we see the difference between a Typical configuration (which just adds additional Talk application instances) vs the Split configuration where different Talk components could be spread across different machine resources to optimize infrastructure utilization. 
+See [Serving the Application](/talk/configuration-cli-tools/#serving-the-application)
+
+### Scaling Redis
+
+Redis serves as a general cache and pub/sub broker. We treat all the data stored in Redis as ephemeral, so using as a cache serves us well for Talk to synchronize expensive query caches. It also serves as our pub/sub broker for use with live updates as propagated through the GraphQL subscription system. For this reason it is not recommended to implement multiple instances of Redis. 
+
+### Scaling MongoDB
+
+MongoDB is treated as our general store for persisted data. Talk supports the most common strategies for scaling MongoDB instances including replicas and/or sharding. Depending on your specific data use cases, refer to MongoDBs documentation for more information about scaling https://www.mongodb.com/mongodb-scale.
+
+### Load Balancer 
+While this subject lives outside the Talk ecosystem, it is critical for application delivery. For websockets to work correctly, a load balancer must be selected that can support long lived connections that are required for websockets to work.
+
+## Running Talk in Production
+
+When you are ready to launch your production instance of Talk update your NODE_ENV environment variable from `development` to `production` mode.
+
+Then launch talk with `yarn start` or with the command `NODE_ENV=production ./bin/cli-serve -j -w`
+
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