We’ve all been there. You go to power on a virtual machine, and instead of a familiar boot screen, you’re greeted by an error: “Failed to open disk: The file specified is not a virtual disk.”
You check the datastore, and everything looks fine—your large flat VMDK (usually named vmname-flat.vmdk ) is sitting right there, taking up 100GB. But its tiny sibling, the descriptor file ( vmname.vmdk ), is missing or corrupted.
Don't panic. You don't need backups of the entire VM to fix this. You just need to rebuild a 1KB text file. restore vmdk descriptor file
Have you recovered a VM using this method? Let me know in the comments below!
ls -la *.vmdk stat vmname-flat.vmdk You need the . Write this number down. We’ve all been there
Always take a checksum (MD5) of the -flat.vmdk before editing. One wrong space in the descriptor file is fine—it will throw an error. One wrong offset? That corrupts the partition table.
Create a new file named exactly like the original (e.g., WindowsServer.vmdk ) using vi or nano . Don't panic
# Disk DescriptorFile version=1 CID=fffffffe parentCID=ffffffff createType="monolithicFlat" RW [SIZE_IN_SECTORS] VMFS "vmname-flat.vmdk" The Disk Data Base #DDB