Low disk space on LUN after deleting vm checkpoints on Hyper-v and stuck in "merge in progress" state

Ghasem Shams 1 Reputation point


We had a large virtual machine on Hyper-V with 3 checkpoints. The checkpoints have been deleted, but due to insufficient space on the LUN, it remains in a "merge in progress" state. The virtual machine was shut down before deleting the checkpoints. The total size of the mrt, rct, and avhdx files for one disk is 6 terabytes, while the disk (vhdx) itself is 9 terabytes. The LUN has a capacity of 15 terabytes and is currently full. In the current situation, what is the best action to prevent data loss and turn on the virtual machine?

The first priority is to turn on the virtual machine with its current state and continue its operation until an appropriate time.

If this is not possible, what is the quickest and most assured way to resolve this situation? The virtual machine does not have a backup. We can empty another LUN and add its space to the LUN that is running out of space. Will this action continue the merge process, and furthermore, will it allow us to turn on the virtual machine?

Thansk in advance

A Windows technology providing a hypervisor-based virtualization solution enabling customers to consolidate workloads onto a single server.
2,571 questions
0 comments No comments
{count} votes

2 answers

Sort by: Most helpful
  1. Ian Xue (Shanghai Wicresoft Co., Ltd.) 31,166 Reputation points Microsoft Vendor

    Hi Ghasem,

    Hope you're doing well.

    As the LUN is currently full and the merge process requires additional space, the first step is to allocate more storage space to the LUN. Since there's insufficient space available, you can empty another LUN and add its space to the LUN that is running out of space.

    Once additional storage space is allocated, the merge process should resume automatically. It's essential to ensure that there's enough free space on the LUN to accommodate the merge process. Depending on the size of the files and the available storage speed, the merge process may take some time to complete.

    In summary, the priority is to allocate sufficient storage space, resume and monitor the merge process, verify data integrity, and bring the virtual machine back online. If necessary, implement temporary measures to address space constraints and ensure the successful resolution of the issue.

    Best Regards,

    Ian Xue

    If the Answer is helpful, please click "Accept Answer" and upvote it.

    0 comments No comments

  2. Ghasem Shams 1 Reputation point

    Thanks for getting back to me, Ian. We discovered that deleting the snapshot wasn't successful, as shown in the logs. Although there's no snapshot name in the checkpoints box and the names have been deleted, the snapshot files are still present. I've powered on the VM, and it's functioning, but what are our options after expanding the LUN size? Is manually merging snapshots safe?

    0 comments No comments