Time Drift in VM

Recently, we worked on an issue with time drift in a VM, and my colleague Johann Binder had an interesting finding I‘d like to share with you:  The issue was with a VM that had SQL Server 2008 installed. In the eventlog of the machine we found Informational Events 1, Microsoft-Windows-Kernel-General, “The system time has…

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Problems with Live Migration

Hi, today my collegue Bernd Högen has interesting finding that he would like to share: Recently, I faced the following Issue: On a W2k8 R2 SP1 Hyper-V Host Cluster with 2 CSV´s only the Coordinator Node was able to access the CSV. The other Node(s) did not see the CSV Volume below c:\clusterstorage The CSV Volumes…

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Time Synchronization and Domain Controller VM’s

Hi, often, I’m getting asked how to configure Time Synchronization for Hyper-V VM’s that run the Domain Controller (DC) Role. Our original recommendation was to disable the time synchronization and leave it up to the DC’s own functionality to synchronize time with other DC’s. On the other hand, we also have our PM Bens correct…

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Recent fixes that address slow network throughput on Hyper-V

Hi,   Recently, I’ve been working on several issues where customers reported poor network throughput. This happened on recent and performant hardware, that showed in benchmarking the 10GBit Ethernet connection, or slow Live Migration. The throughput was only about 10 Percent of what is expected. As it turned out, the overall performance suffered, but network throughput…

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How does a NIC inside a VM get a MAC address assigned?

Hi,  If you add a NIC to a VM, it needs a MAC address that should be unique (at least in the network segment) to avoid duplicate MAC conflicts. In the properties for the VM you choose between a Dynamic or Static assignment. In case you select a Static MAC, it is your responsibility that…

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What does "Enable heartbeat monitoring for the virtual machine" do ?

 Hi,  I’ve been asked this a couple of times, and thought it might be interesting to blog..  If you have a R2 Hyper-V Host cluster, the Virtual Machine Resource has a property on the Settings page named “Heartbeat Setting” with an associated check box “Enable heartbeat monitoring for the virtual machine”.    By default, this…

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