Citrix Systems 4.1 manual XenServer Platinum Architecture

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image per server role. The architectural advantages introduced by leveraging the Provisioning Server component of XenServer Platinum can be seen in Figure 3.

			XenServer Resource Pool
			Core Business	Core Business	Core Business	Core Business
			Apps	Apps	Apps	Apps	Data Store
			LMG	LMG	LMG	LMG
			Core Business	Core Business	Core Business	Core Business
Centers			Apps	Apps	Apps	Apps
	Web Interface	Data Collector	LMG	LMG	LMG	LMG
							Application
							Hub
	Web Interface	Data Collector	Business Unit		Line-of-
Data
			LoB		Business
			LMG		LMG
for			Business Unit		Line-of-		License Server
			LoB		Business
Provisioning Server
			LMG		LMG
				Line-of-Business
				LMG

Figure 3: XenServer Platinum Architecture

With the defined XenApp architecture, there are five distinct roles:

1.	Web Interface	3.	Core Business Apps	5. Line-of-Business
2.	Data Collector	4.	Business Unit Line-of-
			Business

Each role would have its own base server image. The image would be created and maintained as a single entity. For common/shared images, this one image would then be delivered (streamed) to any number of physical or virtual servers, which can be easily changed through the management console. The common or shared images are read only. Changes made to the system are lost upon reboot. This guarantees that unforeseen changes will not impact a server.

The power of this solution is based on the ease of management and maintenance of the images. If there are 100 core application servers, this solution only requires changes to be made to the common image. All 100 core application servers will receive the changes without administrative intervention. This solution also makes it easier to add new capacity to deal with surges in usage. If capacity needs to be made to the Line-of-Business group of servers, then the base image for that role would be applied to other server objects within the console, regardless of the server object being a physical or virtual server. When that server starts, it will become a Line-of-Business server.

As there is one image for hundreds of servers, all servers within the role share the same characteristics (operating system, application, configuration settings, computer name and SID). Every server belonging to the role is identical except for a MAC address. This one image must be capable of taking on different identities in order to function properly in a XenApp environment. This is achieved through the Preparation, Startup and XenApp Integration phases:

Preparation Phase: Before an image is delivered to multiple servers, the image must be prepared appropriately.

∙To be integrated into Active Directory, the defined server, within the Provisioning Management console, must be added to Active Directory. Provisioning Server uses standard Windows API calls to add the server into the correct domain and organizational unit.

∙Provisioning Server is also set to manage computer account password with Active Directory so the provisioned servers will be able to authenticate with Active Directory.

∙Before a XenApp server is delivered, an integration utility must be executed to prepare the server for XenApp provisioning. XenApp services are stopped, local host cache instances are cleared and computer names are