Configuration Scenarios

Three example Server Farm configuration scenarios help clarify the options and what variables can be manipulated to adapt your organizational needs.

No two Cherwell Server Farms are identical because of the load they are under, the CSM content and configuration, as well as their usage can differ dramatically from Customer to Customer. In the examples, we assume that your network, load balancer, and SQL infrastructure are inherently scalable to the size needed. The three example scenarios are:
  • Minimal server farm.
  • Server farm and independent services.
  • Maximum distribution of services.

Design Best Practices

When designing the configuration for the Cherwell Server Farm, remember these best practices:

  • 1 CPU core per 50 concurrent Users; minimum of two to start.
  • 10 MB of memory per session for Redis Servers; 2 CPU cores per server.
  • 50 MB of memory per session for Cherwell Application and Web Servers, plus Redis memory.
  • 500 MB of storage per license per year.
  • Redis must be deployed in a high-speed, low-latency, directly-connected environment. This is typically a 10 GbE network (dedicated is best).
  • When promoting from a single server to a Cherwell Server Farm model, remember that a Cherwell Server Farm incurs overhead that lowers the number of concurrent Users serviced by a single machine. Performance and high availability convention is three load-balanced servers = a single server.

Hardware Considerations

Some scaling can typically be done in a single-server scenario just by adding CPUs and memory to the one machine. Such a proposition usually costs more than increasing the number of commodity servers in a Cherwell Server Farm. The example scenarios assume each machine in the Cherwell Server Farm is a commodity box.

Cost considerations for Commodity Hardware

If CSM is installed on a single server using a big server approach (8 core, 32 GB and up) and not commodity hardware (4 core, 16 GB). Determine if the same hardware configuration should be kept for each server or if there is a cost saving opportunity by moving to commodity hardware when moving to a Cherwell Server Farm. If you decide to move to less expensive hardware, there is no exact equation for how many servers are needed, but keep the following in mind: Load-balanced servers are typically CPU heavy, so the CPU is the first and most important factor in the multiplier.