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Tuesday, October 23, 2018

What are VM snapshots intended to be used for?

What are VM snapshots intended to be used for?

  • To shut down the server
  • As a backup tool for your VMs
  • To create albums
  • To easily revert the VM to an earlier state 

What are VM snapshots intended to be used for?


Snapshots provide a fast and easy way to revert the virtual machine to a previous state. For this reason, virtual machine snapshots are intended mainly for use in development and test environments. Having an easy way to revert a virtual machine can be very useful if you need to recreate a specific state or condition so that you can troubleshoot a problem.
There are certain circumstances in which it may make sense to use snapshots in a production environment. For example, you can use snapshots to provide a way to revert a potentially risky operation in a production environment, such as applying an update to the software running in the virtual machine.
Many backup products use snapshots in a production environment. They create a snapshot and then processing continues from the snapshot, meanwhile they have an unchanging original to back up. Once the backup is completed the snapshot is merged back into the live environment. This allows a machine to be backed up with very little affect for the users and for them remains up 24/7.
NB: Hyper-V snapshots do not replace backups. Backup usually involves some form of duplication (so two copies of the protected data exist) but in snapshots... there is no duplication whatsoever. All data is in VHD(X) file and changes in AVHD(X) file and if the VHD(X) file is damaged/lost, the data is pretty much gone. Also with most backups you can restore a single file to an earlier state, but with Snapshots, it's all or nothing (meaning if an user wants a file from last week, you'd have to bring the whole system back a week). There are other concerns as well (there might be performance  issues with multiple snapshots, snapshots usually lose value as they age and there are issues with disk space)



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