RDS Hardware Sizing and Capacity Planning Guidance.
We always felt the need of Hardware capacity guidance and sizing information for Terminal Services or Remote Desktop services for Server 2008 R2, Whenever I am engaged in any architectural guidance discussion for RDS deployment i always get a question what needs to be taken into consideration while deciding the hardware configuration and to do capacity planning.
Here are some bullet points which I recommend to my partners and customers to consider:
- 2GB Memory (RAM) is the optimum limit for each core of a CPU. E.g. If you have 4 GB RAM then for optimum performance there should be Dual core CPU.
- 2 Dual Core CPU perform better then single Quad core processor.
- Recommended bandwidth for LAN of 30 users and WAN of 20 users. Bandwidth (b) = 100 megabits per second (Mbps) with Latency (l) Less than 5 milliseconds.
- On a Terminal Server 64 MB per user is the Ideal Memory (RAM) requirement for GP Only use + 2 GB for OS E.g. (100 users * 64) + 2000 = 8.4 GB i.e. 8GB RAM.
- More applications used (i.e. Office, CAD Apps and etc.) will require more memory per user to be added to this calculation over the 64 MB base memory per user.
- 15 TS session per CPU core is the optimum performance limit of a Terminal Server.
- Network should not have more than 5 hops, and latency should be under 100ms.
- 64 kbps is the Ideal Bandwidth per user session. (256 color, switched network, bitmap caching only)
- CPU performance degrades if %processor time per core is constantly above 65%.
- Terminal servers performance doubles when it is running on a X64 HW and OS.
In addition to that, Microsoft has just released a whitepaper on Capacity Planning in Windows Server 2008 R2.
The Remote Desktop Session Host (RD Session Host) role service lets multiple concurrent users run Windows®-based applications on a remote computer running Windows Server® 2008 R2. This white paper is intended as a guide for capacity planning of RD Session Host in Windows Server 2008 R2. It describes the most relevant factors that influence the capacity of a given deployment, methodologies to evaluate capacity for specific deployments, and a set of experimental results for different combinations of usage scenarios and hardware configurations.
You can also use this document for sizing Terminal Services on a Hyper V Platform
Also use the Remote Desktop Load Simulation Tools available at following link to do the load testing for number of users on RDS Server
I hope it helps, Let me know if you have any questions.