The checkpoint tree as it is called provides a hierarchical view of the checkpoints in existence on a Hyper-V virtual machine. Hyper-V Manager provides an easy and intuitive GUI interface to merge checkpoints. Generally, most Hyper-V administrators will resort to using Hyper-V Manager as the tool of choice if they have only a single Hyper-V checkpoint that needs to be merged on a single virtual machine. Merge Hyper-V Checkpoints with Hyper-V Manager Since it is well established that Hyper-V checkpoint merge operations are a necessary best practice to keeping a Hyper-V environment running efficiently and performing as expected, let’s take a look at the various methods for merging Hyper-V checkpoints. Lingering checkpoints lead to issues across multiple fronts.
These are some of the more important reasons that Hyper-V checkpoints need to be managed in such a way that unnecessary checkpoints are merged appropriately and in a timely manner. When unnecessary checkpoints are in existence on a Hyper-V virtual machine, there is more likelihood of corruption of the virtual disks.Īdditionally, unnecessary checkpoints in existence on a Hyper-V virtual machine can lead to data protection solutions not being able to effectively make use of Resilient Change Tracking mechanisms to ensure only the changes are copied across since the last backup operation was performed. Keeping checkpoints merged and the virtual machines clear of longstanding checkpoints ensures performance is optimal and space is not unnecessarily being consumed. Checkpoints will continue to grow on disk the longer they are left on a Hyper-V virtual machine. Even though all writes on the virtual machine are captured in the current checkpoint AVHDX file, data that is read from the virtual machine may have to traverse numerous checkpoints and the base disk which leads to disk latency and poor performance after time. Having multiple checkpoints on a Hyper-V virtual machine leads to inefficiency in the way disk I/O is performed on a Hyper-V virtual machine. In fact, keeping checkpoints around long-term can lead to undesirable effects such as performance degradation. Even though we know this was not the case, this is the magic of virtualization and Hyper-V checkpoints.Ĭheckpoints are not meant to be a permanent fixture of a Hyper-V virtual machine. The end result is the base disk contains all the data and changes made to the virtual machine as if the checkpoint was never created and all changes were simply captured in the base disk. The merge operation basically integrates all the changes made to the virtual machine captured in the differencing disk (AVHDX file) back into the base virtual disk.
If it is decided to keep the changes made to a virtual machine after a checkpoint was created and the software update or other changes were deemed successful, it is time to merge the checkpoint. This provides the protection against failed software updates or other changes made to the virtual machine as if these are not successful, the checkpoint can simply be reverted and the virtual machine is back to the state it was in before the changes were made. This ensures that any new data changes are made to the delta or “differencing” disk. Proper management of Hyper-V virtual machines involves making sure checkpoints are merged back into the base disk.Ĭheckpoints work by creating “delta” disks that house all the new writes to a virtual machine disk. While checkpoints provide tremendously powerful functionality for remediating failed software updates or other issues related to changes made to a Hyper-V VM, they need to be managed properly. Why Hyper-V Checkpoints Need to be Merged
We have covered How to create Hyper-V Checkpoints and Managing Hyper-V Checkpoints in our previous posts. After Hyper-V checkpoints are used however, getting rid of the checkpoints once they have served their purpose is certainly the best practice procedure in managing Hyper-V checkpoints. In the latest releases of Hyper-V, Microsoft has enhanced and added to the checkpoint functionality with even more robust features including production checkpoints and utilizing the benefits of the ReFS file system. Hyper-V checkpoints play a key role in the overall lifecycle management of Hyper-V virtual machines as they allow for effectively managing and performing software updates, upgrades, and installations with an effective rollback mechanism when things go badly.