Symptoms

When the Citrix Provisioning Server target device is deployed on a XenServer platform, you experience some of the following symptoms:

• Excessive retries while performing a physical to virtual target build

• Slow ICA performance when using XenDesktop

• Freezing or locking with XenDesktop while using Windows XP Service Pack 2

• vDisk retries during normal operation when a Windows XP Service Pack 2 virtual machine is already online and in waiting mode

• Slow hosted application launch when using Presentation Server 4.5 and publishing applications in XenDesktop.

"Retry" definition: The client’s driver performs a vDisk I/O by sending a request to the Provisioning Server. If a transaction fails due to a timeout (which is a no-reply timeout), the driver tries to receive the packet again. The retry number is accumulated by the client and reported to the client’s statistics tray.

Cause

Offload parameters, which are not compatible with the Provisioning Server network stack, could be enabled on the physical network adapter. Citrix recommends disabling features such as TCP Offload on the network adapter for the target device.

Workaround

To work around this problem, disable checksum offloading on target device's network adapter. To do so, complete the following procedure after starting up the master target device in Private Image mode:

1. Go to Start > Run, type regedit, and then click OK.

2. Locate the following registry subkey:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters

3. In the right pane, make sure that the DisableTaskOffload registry entry exists. If this entry does not exist, follow these steps to add the entry:

a. On the Edit menu, point to New and then click DWORD Value.

b. Type DisableTaskOffload and then press Enter.

4. Click DisableTaskOffload.

5. On the Edit menu, click Modify.

6. Type 1 in the Value field and then press Enter.

7. Close Registry Editor.

More Information

CTX115658 – The Image Build Process Takes a Long Time to Complete

Microsoft Knowledge Base article 904946