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About Checkpoints

Updated: August 14, 2009

Applies To: Virtual Machine Manager 2008, Virtual Machine Manager 2008 R2, Virtual Machine Manager 2008 R2 SP1

A checkpoint saves the state of each virtual hard disk that is attached to a virtual machine and all of the hard disk's contents, including application data files. For virtual machines on Hyper-V and VMware ESX Server hosts, a checkpoint also saves the hardware configuration information. By creating checkpoints for a virtual machine, you can restore the virtual machine to a previous state.

A typical use of checkpoints is to create a temporary backup before you update the operating system or an application, or make a configuration change on the virtual machine. A checkpoint allows you to restore the virtual machine to its previous state if the operation fails or adversely affects the virtual machine. For virtual machines on Hyper-V and ESX Server hosts, checkpoints are also useful in a test environment where you want to use multiple hardware configurations on a virtual machine.

Creating Checkpoints

You can create checkpoints only for a virtual machine that is deployed on a virtual machine host. You cannot create checkpoints for a virtual machine that is stored in the library.

For a virtual machine that is running on a Hyper-V or VMware host, you can create a checkpoint without stopping the virtual machine. However, for a virtual machine that is running on a Virtual Server host, it is recommended that you shut down the virtual machine before creating a checkpoint.

CautionCaution
If Virtual Guest Services is not installed on a virtual machine that is running on a Virtual Server host, the virtual machine is simply stopped, not shut down. To avoid losing data, ensure that the virtual machine is not in use and that no processes are running on it. For new virtual machines that are created in Virtual Server hosts, VMM automatically installs Virtual Guest Services.

For checkpoints created when the virtual machine is running
  • The checkpoint contains the state of the hard disks and the data in memory.

  • On the Checkpoints tab, the icon for the checkpoint has a small green triangle.

For checkpoints created when the virtual machine is stopped
  • The checkpoint contains the state of the hard disks only.

  • On the Checkpoints tab, the icon for the checkpoint has a small red square.

You can create multiple checkpoints for a virtual machine. However, checkpoints use hard disk space and, when allowed to proliferate, they can affect the performance of a virtual machine when it is running and during such virtual machine operations as migrating a virtual machine or storing it to the library. For this reason, it is a best practice to remove unneeded checkpoints. For more information, see How to Remove a Checkpoint.

The following table shows the maximum number of checkpoints and branches that you can create for each type of virtualization software supported by VMM.

 

Virtualization software Maximum checkpoints

Hyper-V

50

Virtual Server

64

VMware ESX Server

Limited by disk space

For more information about creating a checkpoint, see How to Create a Checkpoint.

Managing Checkpoints

After you create checkpoints, you can perform additional actions to manage them.

Use the Restore action to restore a virtual machine to its state when a checkpoint was created. For more information, see How to Restore a Virtual Machine to a Checkpoint.

When you no longer need to restore a virtual machine to a checkpoint, you can remove the checkpoint. For more information, see How to Remove a Checkpoint.

For Hyper-V and Virtual Server hosts, checkpoints are portable. When you migrate, store, or deploy a virtual machine, any existing checkpoints move with the virtual machine.

VMM administrators can grant self-service users permission to create and manage checkpoints for their virtual machines. For more information, see How to Create a Self-Service User Role. For information about creating and managing checkpoints through the VMM Self-Service Portal, see Self-Service Portal Help on the portal Web site.

Checkpoints Are Not Intended for Backup

Checkpoints are intended to provide a temporary backup when you need to restore a virtual machine to a previous state after a change, such as a system or application update. However, you should not use checkpoints for the permanent backup of the operating system, applications, or files.

Checkpoints are stored with the virtual machine on the host. Therefore, if the host fails while the virtual machine is deployed, the checkpoints are lost. To provide data protection for your virtual machines, you should instead use the Volume Shadow Copy Service (VSS) writer for Virtual Server or a backup application, such as System Center Data Protection Manager (DPM), to back up your virtual machines to external storage.

If your virtual machines store user data files, it is important to back up the data files on a virtual machine before you restore the virtual machine to a checkpoint. When you restore the virtual machine, user data files on its virtual hard disks are returned to their previous state.

See Also

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