Snapshot vApp/VMs

A snapshot (recovery point) can be made for a vApp or VM. Typically this would be done prior to making changes.

 

For more information, see the VMware help page: Best Practices for Using Snapshots in the vSphere Environment


Topics


Guidelines for Using Snapshots

Follow these guidelines when using snapshots:

 

Guideline Reason
Do not use snapshots as backups.

The snapshot file is only a change log of the original virtual disk. It creates a place holder disk (virtual_machine-00000x-delta.vmdk) to store data changes since the time the snapshot was created. If the base disks are deleted, the snapshot files are not sufficient to restore a VM.

Do not use a single snapshot for more than 24-72 hours.

The snapshot file continues to grow in size when it is retained for a longer period. This can cause the snapshot storage location to run out of space and impact system performance.

Delete snapshots when they are no longer required.

Snapshots consume disk space. You should delete them once they have been used, to allow the disk to be available for other VMs.

 


Snapshot a vApp/VM

 

Warning: Only one snapshot can be present at a time. If a snapshot already exists, it will be deleted before the new snapshot is created.

Follow these steps:

 

1. From the Virtual Machines tab, locate the VM you want to snapshot. Select Actions > Create Snapshot

 

 

2. Select from the snapshot options and click OK. See Memory and Quiesce States below for more information about the options. 

 

 


Memory and Quiesce States

The following definitions apply to the memory and quiesce states:

 

State Description Note
Memory

If the <memory> flag is 1 or true, a dump of the internal state of the VM is included in the snapshot.

 

Memory snapshots take longer to create, but allow reversion to the VM's running state when the snapshot was taken. 

 

If this option is not selected, and quiescing is not selected (see below), the snapshot will create files which are crash-consistent and can be used to reboot the VM.

When taking a memory snapshot, the entire state of the VM will be stunned.

 

For more information, see the VMware Knowledge Base Article: Taking a snapshot with virtual machine memory renders the virtual machine to an inactive state while the memory is written to disk (1013163)

 

Quiesce

If the <quiesce> flag is 1 or true, and the VM is powered on when the snapshot is taken, VMware Tools is used to quiesce the file system in the VM.

 

Quiescing a file system is the process of bringing the on-disk data of a physical or virtual computer into a state suitable for backups. This process might include such operations as flushing dirty buffers from the operating system in-memory cache to disk, or other high-level application-specific tasks.

Quiescing indicates pausing or altering the state of running processes on a computer, particularly those that might modify information stored on disk during a backup, to guarantee a consistent and usable backup.

 

Quiescing is not necessary for memory snapshots and is used primarily for backups.

 

 


Restore a VM/vApp From a Snapshot

 

Warning: Restoring from a snapshot will discard ALL changes made since the snapshot was created.

To restore a VM/vApp from a snapshot, follow these steps:

 

1. Locate the VM you want to restore. The VMs with a snapshot will display a small blue dot above the Storage icon as shown below.

 

 

2. To revert to a snapshot (recovery point), select Actions > Revert to Snapshot. This operation may take some time to complete.

 


Delete a vApp/VM Snapshot

To delete a snapshot when it is no longer required, follow these steps:

 

1. Locate the vApp or VM with the snapshot to be deleted. The vApps or VMs with a snapshot will display a small blue dot above the Storage icon as shown below.

 

 

2. Select Actions > Remove Snapshot. This will keep the VM in its current state and remove the recovery point. This operation may take some time to complete.


 

 

 

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