As explained in Virtualizing the GN4 environment, GN4 is compatible with various virtualized environments, included VMWare and vCenter. However, there's an issue in Microsoft Windows that can cause a general system slow down and/or applications freeze. Generally the Windows event log shows this error: (Error: A general system error occurred: Invalid response code: 503 Service Unavailable).

A Microsoft hot-fix exists for the aforementioned problem.

This problem affects only vCenter Servers running on Windows Vista or Windows Server 2008. Under a heavy load, some of the operations invoked on the vCenter Server fail and the error description indicates the HTTP error 503 Service Temporarily Unavailable. The exact error message might differ depending on the client, because it is generated by the client.

The vpxd log files contain entries that indicate that a socket connection attempt failed because it timed out. If you run netstat -an on the vCenter Server host machine immediately after the error, you will see many connections where one end is port 8085 on the loopback and the other end is another port on the loopback. Some of these connections will be in the TIME_WAIT state.

vCenter Server uses TCP connections on the loopback (localhost) for Remote Procedure Calls (RPC) to dispatch client requests and to communicate with vCenter Server companion services. As a result, under heavy loads, vCenter Server creates many local TCP connections, then closes them and opens new ones. Some of the closed connections remain open at the server side in the TIME_WAIT state for some time (four minutes with default Windows settings). Because the number of client-side ports is limited, if vCenter Server uses the connections fast enough, at some point the client side tries to reuse a port while the server side still has a connection for this client port in the TIME_WAIT state.

Normally, this situation should prompt the server to close the old connection and accept the new one. But on Windows Vista or Windows Server 2008, a documented flaw in the TCP stack might instead cause the server side to ignore the connection request. If this happens, the client retries several times and then times out. In this case, the vCenter Server dispatcher fails to contact the service and returns a 503 Service Unavailable error to the client, and the client request fails.

From VMware Knowledge base portal, it lead to Microsoft Support http://support.microsoft.com/kb/2577795 (Kernel sockets leak on a multiprocessor computer that is running Windows Server 2008 R2 or Windows 7).

See also

•http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2033822

•http://support.microsoft.com/kb/2577795