Windows hyper-v packet drop

Question

Hi, Recently we have upgraded our network from 1gig to 10gig. After network upgrade, We have started observing packet drops on hyper-v virtual machine. We are using hyper-v 2019. We have 1 hyper-v cluster with 2 nodes and 1 standalone hyper-v server. On standalone server, things are good but on hyper-v cluster there are intermittent packet drops. Need to know what to check in hyper-v cluster.

Answer 1

Hello Kapil,

Thank you for your question and for reaching out with your question today.

When experiencing packet drops on Hyper-V virtual machines after a network upgrade, there are several areas you can investigate within your Hyper-V cluster to help troubleshoot the issue:

1. Network Adapter Settings: Verify that the network adapter settings on your Hyper-V cluster nodes are configured correctly. Ensure that the network adapter properties, such as speed and duplex settings, are set appropriately for the 10Gig network. Also, confirm that any advanced features like Large Send Offload (LSO) or Receive Side Scaling (RSS) are properly configured.
2. Virtual Switch Configuration: Check the configuration of the virtual switches on your Hyper-V cluster. Verify that the virtual switches are bound to the correct physical network adapters and that the settings, such as VLAN tagging or Quality of Service (QoS), are configured appropriately for your network infrastructure.
3. Network Adapter Drivers and Firmware: Ensure that you have the latest network adapter drivers and firmware installed on your Hyper-V cluster nodes. Outdated or incompatible drivers can cause performance issues and packet drops. Check the manufacturer's website for the latest drivers and firmware updates specifically for your network adapters.
4. Network Path: Investigate the network path between the Hyper-V cluster nodes and the physical switches. Check for any issues with network cables, connectors, or other physical components that may be causing intermittent packet drops. Additionally, verify that the switch ports connected to the cluster nodes are properly configured and functioning correctly.
5. Network Traffic Monitoring: Utilize network traffic monitoring tools to analyze the network traffic patterns and identify any specific sources or destinations where the packet drops are occurring. This can help pinpoint potential bottlenecks or misconfigurations in the network.
6. Hyper-V Integration Services: Ensure that the Hyper-V Integration Services are up to date on the virtual machines running on the cluster. These services provide optimized communication between the virtual machines and the host, and outdated integration services can cause performance issues.
7. Hypervisor Performance Monitoring: Monitor the performance of the Hyper-V cluster nodes to identify any resource constraints or performance bottlenecks. Check CPU usage, memory utilization, and disk I/O to determine if the nodes are adequately provisioned to handle the increased network load.

If the issue persists after checking these areas, it may be beneficial to engage with your network administrator, Hyper-V vendor support, or a qualified IT professional to further investigate and troubleshoot the packet drops in your specific Hyper-V cluster environment.

I used AI provided by ChatGPT to formulate part of this response. I have verified that the information is accurate before sharing it with you.

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Best regards.

Answer 2

Hey,

Which NICs are you using? The issue might be related to VMQ enabled on Broadcom NICs or Intel 710.
https://learn.microsoft.com/en-us/answers/questions/108148/hyper-v-cluster-issues-event-id-252-10400

I've faced similar issues, ended up with disabling it on the NICs. In addition, if you're using NIC teaming, you can try disabling it and reproduce your issue.

Speaking about your setup, since you are using 2 nodes, you can use their local storage in Failover Cluster with StarWind VSAN. It will create replicate shared storage pool from local storage. https://www.starwindsoftware.com/starwind-virtual-san

Cheers,  
Alex Bykovskyi  
StarWind Software  
Note: Posts are provided “AS IS” without warranty of any kind, either expressed or implied, including but not limited to the implied warranties of merchantability and/or fitness for a particular purpose.

Answer 3

Firstly, ensure that your virtual machine is properly configured for dynamic memory. You can activate dynamic memory by accessing Hyper-V Manager, right-clicking on your virtual machine, selecting "Settings," and then navigating to the Hardware tab. Under Memory Management, choose "Dynamic" and specify the initial startup and maximum RAM allocations.

It's essential to note that dynamic memory is not supported on legacy operating systems. For dynamic memory to work, your virtual machine must run a Windows 8 or later operating system. Ensure that your VM is using a compatible OS. Another potential roadblock to dynamic memory is insufficient disk space on the host computer. Dynamic memory relies on disk space for memory snapshots, so make sure your host has adequate free space.

If you're still encountering difficulties, examine the Hyper-V event log for any error messages that may provide insights into the problem. Attempt to run the virtual machine on a different host computer. If it operates successfully on an alternate host, the issue may be tied to the original host.

Additionally, verify that your virtual machine has the latest integration services installed, refrain from using third-party memory management tools, and consider disabling any running antivirus or firewall software on the host computer. If dynamic memory remains problematic despite these efforts, you may need to consider creating a new virtual machine.