Best practices for virtual machine snapshots in the VMware environment (KB1025279)

The following has been taken from VMware Knowledge Base - KB 1025279

  • Snapshots are not backups. A snapshot file is only a change log of the original virtual disk. Therefore, do not rely on it as a direct backup process. The virtual machine is running on the most current snapshot, not the original vmdk disk files.
  • Snapshots are not complete copies of the original vmdk disk files. Taking a snapshot does not create a complete copy of the original vmdk disk file, rather it only copies the delta disks. The change log in the snapshot file combines with the original disk files to make up the current state of the virtual machine. If the base disks are deleted, the snapshot files are useless.
  • Delta files can grow to the same size as the original base disk file, which is why the provisioned storage size of a virtual machine increases by an amount up to the original size of the virtual machine multiplied by the number of snapshots on the virtual machine.
  • The maximum supported amount of snapshots in a chain is 32. However, VMware recommends that you use only 2-3 snapshots in a chain.
  • Use no single snapshot for more than 24-72 hours. Snapshots should not be maintained over long periods of time for application or Virtual Machine version control purposes.

    • This prevents snapshots from growing so large as to cause issues when deleting/committing them to the original virtual machine disks. Take the snapshot, make the changes to the virtual machine, and delete/commit the snapshot as soon as you have verified the proper working state of the virtual machine.
    • Be especially diligent with snapshot use on high-transaction virtual machines such as email and database servers. These snapshots can very quickly grow in size, filling datastore space. Commit snapshots on these virtual machines as soon as you have verified the proper working state of the process you are testing.


  • If using a third party product that takes advantage of snapshots (such as virtual machine backup software), regularly monitor systems configured for backups to ensure that no snapshots remain active for extensive periods of time.




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