Use vSphere Data Protection backup policies to specify virtual machine backup options, the schedule window, and retention policies.

Virtual Machine Backup Options

vSphere Data Protection provides the following options for a virtual machine backup:


Provides full image backups of virtual machines, regardless of the guest operating system.

  • The virtual machine base disk is attached directly to vSphere Data Protection to back up data. vSphere Data Protection uses Changed Block Tracking to detect and back up blocks that are altered.

  • The backup and restore performance is faster because the data flow is through the VMkernel layer instead of over a network connection.

  • A quiesced snapshot can be used to redirect the I/O of a virtual machine disk .vmdk file.

  • HotAdd does not work in multi-writer disk mode.

Network Block Device (NBD)

Transfers virtual machine data across the network to allow vSphere Data Protection to back up the data.

  • The performance of the virtual machine network traffic might be lower.

  • NBD takes a quiesced snapshot. As a result, it might interrupt the I/O operations of the virtual machine to swap the .vmdk file or consolidate the data after the backup is complete.

  • The time to complete the virtual machine backup might be longer than the backup window.

  • NBD does not work in multi-writer disk mode.

vSphere Data Protection Agent Inside Guest OS

Provides backup of certain applications that are running in the guest operating system through an installed backup agent.

  • Enables application-consistent backup and recovery with Microsoft SQL Server, Microsoft SharePoint, and Microsoft Exchange support.

  • Provides more granularity and flexibility to restore on the file level.

Table 1. Virtual Machine Backup Options Design Decisions

Decision ID

Design Decision

Design Justification

Design Implication


Use HotAdd to back up virtual machines.

HotAdd optimizes and speeds up virtual machine backups, and does not impact the vSphere management network.

All ESXi hosts must have the same visibility to the virtual machine datastores. 


Use the vSphere Data Protection agent for backups of SQL databases on Microsoft SQL Server virtual machines.

You can restore application data instead of entire virtual machines.

You must install the vSphere Data Protection agent and maintain it. 

Schedule Window

Although vSphere Data Protection uses the Changed Block Tracking technology to optimize the backup data, to avoid any business impact, do not use a backup window when the production storage is in high demand.


Do not perform any backup or other administrative activities during the vSphere Data Protection maintenance window. Perform restore operations only. By default, the vSphere Data Protection maintenance window begins at 8 PM local server time and continues uninterrupted until 8 AM or until the backup jobs are complete. Configure maintenance windows according to IT organizational policy requirements.

Table 2. Backup Schedule Design Decisions

Decision ID

Design Decision

Design Justification

Design Implication


Schedule daily backups.

Allows for the recovery of virtual machines data that is at most a day old

Data that changed since the last backup, 24 hours ago, is lost.


Schedule backups outside the times of peak demand of production storage.

Ensures that backups occur when the system is least loaded. Verify that backups are completed in the shortest time possible with the smallest risk of errors.

Backups must be scheduled to start between 8:00 PM and 8:00 AM or until the backup jobs are complete, whichever comes first.

Retention Policies

Retention policies are properties of a backup job. If you group virtual machines by business priority, you can set the retention requirements according to the business priority.

Table 3. Retention Policies Design Decision

Decision ID

Design Decision

Design Justification

Design Implication


Retain backups for at least 3 days.

Keeping 3 days of backups enables administrators to restore the management applications to a state within the last 72 hours.

Depending on the rate of change in virtual machines, backup retention policy can increase the storage target size.


Retain backups for cross-region replicated backup jobs for at least 1 day.

Keeping 1 day of a backup for replicated jobs enables administrators, in the event of a disaster recovery situation in which failover was unsuccessful, to restore their region-independent applications to a state within the last 24 hours.

Data that has changed since the last backup, 24 hours ago, is lost. This data loss also increases the storage requirements for vSphere Data Protection in a multi-region configuration.