Server sizing in Microsoft Terminal Services and Citrix XenApp 5.0 environments differs greatly from traditional server environments. Since multiple users simultaneously access these servers, the hardware needs to be dedicated and more robust than that of your traditional member server. In addition, because the Operating System needs to be specifically configured to handle a multi-user environment, these types of servers deal with hardware differently than standard member servers. Other factors include independence from other overhead processes and services that could render the access method useless in the event of their failure, and the security risks associated with hosting user sessions on servers acting as mission critical domain controllers or database servers. The server based computing model as a business access strategy is a proprietary information systems technology requiring a dedicated effort. The goal of any multi-user server based computing deployment is to deliver easy, secure, and high performance access to the end-user. Field testing has produced the following results:
The benchmarking test was conducted with the following configurations to demonstrate the need for dedicated server computing and the break-point for multi-server load balancing and failover.
Dell PowerEdge 2900 III
Dual Intel Quad Core Xeon 2.33GHz
(2 x 74GB SATA) RAID 1 Array
4GB Dual-Ranked DDR RAM
Windows Server 2003 Standard R2
Citrix XenApp 5.0 Enterprise
Microsoft Office Small Business 2007
DELL Optiplex 755 Tower Desktop
Intel Core 2 Duo 2.66GHz
2GB DDR2 RAM
Windows VISTA Business
A server’s degradation point was reached when its score fell below 80. The results showed a maximum of 177 simulated users concurrently running Microsoft Office applications before this threshold was reached. In this test environment, increasing the number of concurrent users beyond this would have resulted in decreased server and end-user performance. Most production environments deploy applications with much higher system resource requirements that reduce the maximum number of users supported by a single server before performance degradation. Server scaling is environment specific based on application overhead and end-user interaction classified as task oriented or power usage. This test was based on task oriented only. Dedicated computing is required regardless of circumstance.
1. Resource Usage: Citrix, a database driven application, makes usage of the server's hardware and operating system resources in a proprietary way that can be incompatible with Visual Database processing and performance.
2. Security & Continuity: Enabling end-user access to a database server for the purpose of hosting virtual work environments puts the production VISUAL Database at risk for a mission critical failure due to unrelated server usage.
3. Hardware Compatibility: VISUAL Database servers operate most efficiently on a Disk Subsystem configuration of RAID 1, 5. Multi-user servers operate most efficiently on a Disk Subsystem configuration of RAID 1 for simultaneous read/write operations. In addition, memory allocation switches differ between Citrix application servers and VISUAL Database servers when configuring virtual vs. conventional memory usage.