Resolve Communication Issues in SCVMM - Part 1

Disable Task Offloading and Update WMI

Communications issues with SCVMM can take on the form of access denied, timeouts, and often as intermittent connectivity issues. The steps in this post are the same ones I use to resolve a good number of customer issues.

Feedback on this article is welcome. If you have technical questions please post them appropriately in the forums:

http://social.technet.microsoft.com/Forums/en-US/category/virtualmachinemanager/

Two types of issues are addressed here

1) Many new settings available to NIC drivers that do not always function as well as would be expected.

2) SCVMM relies heavily on WMI. The updates listed in this article resolve issues with WMI that will allow SCVMM to function properly.

This MDSN article lists all values available.

Using Registry Values to Enable and Disable Task Offloading
http://msdn.microsoft.com/en-us/library/aa938424.aspx

WMI

Install three WMI updates on all Windows 2008 server running Hyper-V (and therefore are SCVMM Hosts)

958124 A wmiprvse.exe process may leak memory when a WMI notification query is used heavily on a Windows Server 2008-based or Windows Vista-based computer

http://support.microsoft.com/default.aspx?scid=kb;EN-US;958124

954563 Memory corruption may occur with the Windows Management Instrumentation (WMI) service on a computer that is running Windows Server 2008 or Windows Vista Service Pack 1

http://support.microsoft.com/default.aspx?scid=kb;EN-US;954563

955805 Certain applications become very slow on a Windows Server 2008-based or Windows Vista SP1-based computer when a certificate with SIA extension is installed

http://support.microsoft.com/default.aspx?scid=kb;EN-US;955805

Network Settings

NOTE

- If working with a core server you may want to connect via remote registry and make these changes.
- All values should be set to '0' EXCEPT for the last one which is related to IPSEC, and thus Kerberos. Leave this one alone ---> 'HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Ipsec\EnabledOffload'

1 - Locate all physical NICs in the registry under:
'HKLM\System\CurrentControlSet\Control\Class\{4D36E972-E325-11CE-BFC1-08002BE10318}'

2 - There will be folders with four digits, starting with '0000'. Locate the ones that show the physical NIC names on the right. Look for the 'DriverDesc' value on the right; this should have the name of a NIC such as 'HP NC360T PCIe Gigabit Server Adapter.' For each of these, make the changes below.

3 - Disable All Vendor specific Offloading
Set values for any entries below that include the word 'Offload' to '0' (Disabled)
*FlowControl

     No description available

*IPChecksumOffloadIPv4
Describes whether the device enabled or disabled the calculation of IPv4
checksums.
*TCPChecksumOffloadIPv4
Describes whether the device enabled or disabled the calculation of TCP Checksum
over IPv4 packets.
*TCPChecksumOffloadIPv6
Describes whether the device enabled or disabled the calculation of TCP checksum
over IPv6 packets.
*UDPChecksumOffloadIPv4
Describes whether the device enabled or disabled the calculation of UDP Checksum
over IPv4 packets.
*UDPChecksumOffloadIPv6
Describes whether the device enabled or disabled the calculation of UDP Checksum
over IPv6 packets.
*LsoV1IPv4
Describes whether the device enabled or disabled the segmentation of large TCP
packets over IPv4 for large send offload version 1 (LSOv1).
*LsoV2IPv4
Describes whether the device enabled or disabled the segmentation of large TCP
packets over IPv4 for large send offload version 2 (LSOv2).
*LsoV2IPv6
Describes whether the device enabled or disabled the segmentation of large TCP
packets over IPv6 for large send offload version 2 (LSOv2).
*IPsecOffloadV1IPv4
Describes whether the device enabled or disabled the calculation of IPsec headers
over IPv4.
*IPsecOffloadV2
Describes whether the device enabled or disabled IPsec offload version 2
(IPsecOV2). IPsecOV2 provides support for additional crypto-algorithms, IPv6, and
co-existence with large send offload version 2 (LSOv2).
*IPsecOffloadV2IPv4
Describes whether the device enabled or disabled IPsecOV2 for IPv4 only.
*RSS
Receive side scaling
*TCPUDPChecksumOffloadIPv4
Describes whether the device enabled or disabled the calculation of TCP or UDP
checksum over IPv4.
*TCPUDPChecksumOffloadIPv6
Describes whether the device enabled or disabled the calculation of TCP or UDP
checksum over IPv6.

4 - Disable Offloading in Windows.
Use the following registry values to enable or disable task offloading for the TCP/IP protocol:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\TCPIP\Parameters\DisableTaskOffload

Setting this DWORD value to ‘1’ disables all of the task offloads from the TCP/IP transport. Setting this value to zero enables all of the task offloads.

Related Links
Network Issues with Windows Server 2008 RDP and VS/Hyper-V on Dell Servers
http://www.petri.co.il/network-issues-with-windows-server-2008-rdp-on-dell-servers.htm