A VM has had a snapshot for months and is now slow or corrupt.
Snapshots in Hyper-V (.avhdx) and VMware (-delta.vmdk) are delta disks, not backups. The longer they live, the longer the chain and the higher the risk of corruption when the host fails.
Try this first
- 1Before anything else, take a Veeam or equivalent backup of the VM in its current state. Merging a snapshot can fail.
- 2Inventory the chain: in VMware via Snapshot Manager or the folder with -delta files, in Hyper-V via Get-VMSnapshot and the .avhdx files.
- 3Plan a maintenance window, gracefully stop applications if the VM runs a database, then start the consolidation or snapshot delete.
- 4Watch the merge: in VMware it can take hours with large deltas, in Hyper-V it merges automatically on delete. Do not reboot halfway.
- 5After consolidation: re-check the VM (chkdsk on Windows, fsck on Linux), test the application, and keep the backup until you are certain everything is good.
When to bring us in
If the merge fails due to disk corruption or a full datastore, restore from the pre-merge backup to a new VM and pick up from there. Do not keep retrying on a shaky chain.
See also
- One DC or two DCs for an SMB office?Two is almost always the right answer; one DC is a single point of failure for logon, DNS and GPOs.
- Should I split FSMO roles across two DCs?For a small domain all on one DC is fine; with two DCs splitting is tidier but not required.
- How do I know my AD replication is healthy?Replication errors creep in silently; they only surface when logins or GPOs misbehave.
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