Server Load
In addition the total number of sessions, the amount of work being done by the server need to be factored into the capacity planning.
One factor is the demand generated by the clients. The rate at which the data will flow affects the workload. Intermittent screen access such as a loan fulfillment application would generate less workload than a teller application in constant use. The amount of data flowing will also affect the workload. Typically 3270 screen based application will generate small amounts of data, where as a file transfer or print job will send full packets of data.
Another factor is the other services being provided by the server. If the server is exposing the sessions through the TN3270 service, there will be a moderate increase in workload. Additional resources should be considered (e.g. additional CPU) or reduction of total sessions. If the server is providing print session emulation through the SNA Print service, this can greatly increase the workload. Print sessions configured to use PDT files create a small increase in workload. Print sessions configured for GDI will create a large increase in workload. Typically customers will isolate print sessions to a dedicated server.
In addition to the Host Integration Server services, there can be other services and functions performed by the server, such as hosting a database or providing Windows printing services. It is difficult to predict exactly how much processing power is required to run multiple server applications. In many cases, your own requirements to meet a certain level of response time or transaction rate will indicate the specific hardware requirements for your environment.
The following table provides a general guideline for hardware requirements.
| Per Server | Guidelines |
|---|---|
| 1000-5000 Users 15,000 Sessions | - Multiprocessor system with at least 8GB RAM - Gigabit Ethernet connections - Multiple LAN adapters to reduce bottlenecks |
| 200-1000 Users 5,000 Sessions | - Dual processor system with at least 4GB RAM - Gigabit Ethernet connection |
| 1-200 Users 1,000 Sessions | - Single processor system with at least 2GB RAM - Gigabit Ethernet connection |