VM snapshot files

Each virtual machine snapshot in vSphere consists of a number of files, such as:

  • delta disk file – holds the state of the virtual disk at the time the snapshot was taken. The VM’s original .vmdk file is placed in read-only mode to preserve its state.
  • memory state file – holds the memory state at the time the snapshot was taken. The size of this file is the size of the VM’s maximum memory. The memory state file has an .vmsn extension.
  • disk descriptor file – a small text file that contains information about the snapshot.
  • snapshot delta file – contains the changes to the virtual disk’s data at the time the snapshot was taken. This delta disk is used for all disk writes, since the VM’s original .vmdk file is placed in read-only mode. This file has an delta.vmdk suffix.
  • snapshot list file – created at the time the VM is created, this file keeps track of the VM’s snapshots.
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