One of the first questions when virtualizing XenApp is how many VMs to put on a server. Well, that was discussed in the Virtualize XenApp blog. Once you figure out how you plan to carve up the physical server, one of the next common questions is deciding which features of the hypervisor to enable/disable. For example, if I use XenServer, should I use the “Optimize for XenApp” setting? What about vSphere’s Transparent Page Sharing feature?
Here is a pretty common question… I want to virtualize my XenApp servers, how should I carve the physical server up? Should I use a bunch of small VMs or a few massive VMs?
First, you have to look at a few decision points:
OS Scalability: This is more of an issue in Windows 2003. Operations: More VMs means more to manage, unless you use a single image management solution like Provisioning Services.
SpeedScreen Folder
The SpeedScreen folder contains a rule that enables you to remove or alter compression. When client connections are limited in bandwidth, downloading images without compression can be slow.
Image Acceleration Using Lossy Compression
This rule defines ways in which images can be compressed to improve the responsiveness of graphics-intensive applications:
Normal lossy compression Progressive display compression Heavyweight compression If your server farm includes servers running different releases of XenApp, you may not be able to apply all of these image acceleration techniques to all of the servers in the farm.
XenServer’s VM Protection and Recovery (VMPR) feature provides a simple backup and restore utility for your critical service VMs. Regular scheduled snapshots are taken automatically and can be used to restore individual VMs.
VMPR works by having pool-wide VM protection policies that define snapshot schedules for selected VMs in the pool. When a policy is enabled, snapshots are taken of the specified VMs at the scheduled time each hour, day or week.
Use the New VM Protection Policy wizard to create a VM Protection policy that identifies the VMs in the pool that you want to snapshot, the type of snapshot to be created (disk-only or disk and memory), and the snapshot and archive schedules. You can also configure email notification for snapshot and archive event alerts in the wizard.
To open the New VM Protection Policy wizard: on the Pool menu, click VM Protection Policies to open the VM Protection Policies dialog box, and then click Newto start the wizard.
To enable, disable, edit and delete VM Protection policies for a pool, you use the VM Protection Policies dialog box: on the Pool menu, click VM Protection Policies.
Enabling a VM Protection policy When you enable a VM Protection policy, you turn it “on”: automated snapshots of the specified VMs will then be generated at the scheduled time and archived, if this is also configured. Scheduled snapshots will continue being taken until the policy is disabled.
To recover a VM from a scheduled snapshot To recover a VM from a scheduled snapshot, you simply revert the VM to the specified snapshot.
Select the VM and click on the Snapshots tab. To show scheduled snapshots (by default, they are not shown on this tab): click View and then Scheduled Snapshots. Select the scheduled snapshot you want to revert the VM to and then click Revert To. To take a new snapshot of the current state of VM before reverting it back to the scheduled snapshot, select the check box.
This task requires a system preparation utility, such as Microsoft Sysprep, third-party imaging software, and a text editor.
This task assumes you want to clone a server for the purpose of hosting published applications and that a relational database (Oracle, SQL Server, or DB2) is hosting the data store. C is the drive on which XenApp is installed.
If you are using Citrix Provisioning services, using the PVS PS Integration Utility can accelerate the integration process by automating some steps.
Each XenApp server stores a subset(a portion or part from the whole part, but not full part) of the data store in the Local Host Cache (LHC). The LHC performs two primary functions:
• Permits a server to function in the absence of a connection to the data store.
• Improves performance by caching information used by ICA Clients for enumeration and application resolution.
The LHC is an Access database, Imalhc.
The ICA section contains policy settings related to ICA listener connections, mapping to the Clipboard and custom channels, connecting to server desktops, and controlling the launch behavior of non-published programs.
ICA listener connection timeout Applicable products: XenApp; XenDesktop
This setting specifies the maximum wait time for a connection using the ICA protocol to be completed. By default, the maximum wait time is 120000 milliseconds, or two minutes.
ICA listener port number Applicable products: XenApp; XenDesktop
