What is a checkpoint?

A checkpoint is a saved state of a Virtual Machine at a point in time that can be returned to. Other virtual solutions (notably VMWare) refer to this as a "snapshot." Multiple checkpoints can be created on a single VM, enabling one to jump between machine states quickly and easily for testing purposes.

Creating a checkpoint creates a journal file on the datastore, that logs all of the disk write operations. The original hard disk is unmodified. 

Some third party backup software hooks into Hyper-V and creates checkpoints to use during a backup. It is important that any software that does this cleans up after itself and removes old checkpoints.

More information and details on creating and using checkpoints can be found in Microsofts documentation.

Is a checkpoint the same as a backup?

No. A checkpoint is merely a saved point in time that can be returned to. It is in no way a backup and does not provide any data security.

Important: It is critical to use the correct terminology when discussing snapshots and backups. Misunderstandings can lead to data loss!

Advantages of a Checkpoint

• Quickly create a point in time that can be easily returned to
• Keep several different configurations ready to go for testing purposes

Drawbacks of Using Checkpoints

• Running a VM with an active checkpoint has a performance cost due to writing to the the journal file mentioned above. More checkpoints = more performance cost.
• Creating too many checkpoints can be confusing to administer.
• Leaving a checkpoint active will eventually fill up the disk that the VM resides on. The Journal file grows with each disk write operation, including deletes.

When should I use checkpoints?

Normally you should run your system with no checkpoints enabled. This will provide the best performance. 

You should create a checkpoint before any major configuration changes, including Kodak Workflow Software upgrades. This will enable you to very quickly return to a working state should something fail during the upgrade. 

Note: Please power down the VMs before creating a checkpoint. This is much faster an guarantees application and database consistency.

You should delete the checkpoint after a suitable amount of time has passed and you are satisfied that the upgrade worked properly (usually a maximum of 1 week). 

You do not have to power off the VMs when deleting a checkpoint. Performance will be a bit slow while the journal file is being reintegrates with the virtual hard disks, but will return to normal once the deletion is finished.