Just a quick blog and reminder for something I worked a couple of months ago, or even longer and it took a considerable amount of time to figure out. Then last week a colleague just ping me with a question about a case they have been dealing for quite sometime.

让客户满意是我们工作的目标，不断超越客户的期望值来自于我们对这个行业的热爱。我们立志把好的技术通过有效、简单的方式提供给客户，将通过不懈努力成为客户在信息化领域值得信任、有价值的长期合作伙伴，公司提供的服务项目有：国际域名空间、网络空间、营销软件、网站建设、肥西网站维护、网站推广。

Upon trying to join a second DAG member, in a virtualized Hyper-V environment, the following error message is presented:

“WriteError! Exception = Microsoft.Exchange.Cluster.Replay.DagTaskOperationFailedException: A server-side database availability group administrative operation failed. Error The operation failed. CreateCluster errors may result from incorrectly configured static addresses. Error: An error occurred while attempting a cluster operation. Error: Cluster API ‘”AddClusterNode() (MaxPercentage=100) failed with 0x5b4. Error: This operation returned because the timeout period expired”‘ failed.. —> Microsoft.Exchange.Cluster.Replay.AmClusterApiException: An Active Manager operation failed. Error: An error occurred while attempting a cluster operation. Error: Cluster API ‘”AddClusterNode() (MaxPercentage=100) failed with 0x5b4. Error: This operation returned because the timeout period expired”‘ failed. —> System.ComponentModel.Win32Exception: This operation returned because the timeout period expired”

If you look at the cluster logs you would notice the heartbeat failing on port UDP 3343.

Obviously you need to go by the normal troubleshooting steps of network connectivity and firewall rules. If everything seems right, and as my friend pointed out all knobs were turned and he was ready to give up. That’s when I asked…

Have you disabled TCP/UDP Checksum offload on both host and guest network cards ?

After disabling these options on both guest and parent partition cluster could be formed without any issues.

So in this case, after you make sure the obvious have been checked out and you still cannot join your cluster nodes in a virtual environment, take a look at the NIC properties for TCP/UDP Checksum Offload for IPv4 and IPv6.