Virtual machine backup techniques

Windows Hyper-V backup

You can use IBM Spectrum Protect for Virtual Environments: Data Protection for Microsoft Hyper-V to back up virtual machines that are hosted by a Windows Server operating systems with the Hyper-V role installed.

How it works

For Windows Server 2012, Windows Server 2012 R2, and Windows Server 2016 or later operating systems, Data Protection for Microsoft Hyper-V creates an incremental-forever full or incremental-forever incremental backup of Hyper-V virtual machines in VHDX disk format. The virtual machine is backed up to the IBM Spectrum Protect server. Microsoft Volume Shadow Copy Service (VSS) is used to take a consistent snapshot of the virtual machine. On Windows Server 2016 or later systems, Resilient® Change Tracking (RCT) is used to create snapshots and provide change block tracking capability for Hyper-V VM disks.

Advantages

Hyper-V backup processing has the following advantages:

• This method can back up data without stopping the virtual machine or stopping any running applications within the virtual machine.
• This method can restore either individual virtual machines or a group of virtual machines that run on a Hyper-V server for disaster recovery purposes.
• This method adds backup and restore functions for guest operating systems without the need for you to install an IBM Spectrum Protect client on the guest virtual machine.
• This method can be used for both disaster recovery and long-term data backup support.
• You can run individual file restore operations by using the IBM Spectrum Protect file restore interface in Data Protection for Microsoft Hyper-V Version 8.1.4 or later.

Disadvantages

Hyper-V backup processing has the following disadvantages:

• Backups are not granular.
• You cannot run individual file restore operations from a full virtual machine backup (in Data Protection for Microsoft Hyper-V V8.1.2 or earlier).

For complete information about creating incremental-forever backups of Hyper-V virtual machines, or for information about using the IBM Spectrum Protect file restore interface to restore files from a Hyper-V virtual machine backup, see the IBM® Knowledge Center topics at http://www.ibm.com/support/knowledgecenter/SSERB6.

Virtual machine incremental-forever-full backup

How it works

The following processes occur during incremental-forever-full virtual machine backup processing:

• A full virtual machine backup is required only one time.
• Data from incremental backups is combined with data from the full backup to create a synthetic full backup image. This type of full backup is called a synthetic backup because it is created from the data that is stored on the server and not from reading the used blocks on the production disks.
• Each incremental-forever-full virtual machine backup operation reads and copies all of the used blocks, whether the blocks are changed or not since the previous backup.

Advantages

Incremental-forever-full virtual machine backup processing has the following advantages:

• During a restore operation, you can specify options for a point in time and date to recover data. The data is restored from the original full backup and all of the changed blocks that are associated with the data.

Disadvantages

Incremental-forever-full virtual machine backup processing has the following disadvantages:

• If one or more of the progressive incremental backups is corrupted on the server, you might not be able to fully recover a virtual machine. To ensure that you can fully recover a virtual machine, periodically run a full virtual machine backup.
• This method is available only with data movers that run on Linux and Windows clients.

Virtual machine incremental-forever-incremental backup

How it works

The following processes occur during incremental-forever-incremental backup processing of a virtual machine:

• A full virtual machine backup is required only one time.
• A full virtual machine backup operation copies all of the used disk blocks that are owned by a virtual machine to the IBM Spectrum Protect server.
• After the initial full backup, all subsequent backup operations of the virtual machine are incremental-forever-incremental backups.
• This method copies only the blocks that changed since the previous backup, regardless of the type of the previous backup.
• The server uses a grouping technology that associates the changed blocks from the most recent backup with data that is already stored on the server from previous backups.
• A new full backup is then effectively created each time changed blocks are copied to the server by an incremental-forever-incremental backup.

Advantages

Incremental-forever-incremental backup processing has the following advantages:

• Periodic full virtual machine backups are no longer necessary.
• This method reduces the amount of data that goes across the network.
• This method reduces data growth because all incremental backups contain only the blocks that changed since the previous backup.
• No comparison with the backup target is required since only changed blocks are identified.
• Impact to the client system is minimized.
• The length of the backup window is reduced.
• Data restore operations are simplified.
• This method optimizes data restore operations.

Disadvantages

Incremental-forever-incremental backup processing has the following disadvantages:

• If one or more of the progressive incremental backups is corrupted on the server, you might not be able to fully recover a virtual machine. To ensure that you can fully recover a virtual machine, periodically run a full virtual machine backup.
• This method is available only with data movers that run on Linux and Windows clients.

Parallel backups of virtual machines

You can improve performance of virtual machine backups by running parallel backups of multiple virtual machines by using a single instance of the data mover.

How it works

The following processes occur during parallel backup processing of virtual machines:

• A single IBM Spectrum Protect data mover node can be used to concurrently back up multiple virtual machines.
• When the backups are initiated, the client establishes parallel sessions to copy the data to the IBM Spectrum Protect server.

Advantages

Parallel virtual machine backup processing has the following advantages:

• The backup window is reduced.
• You can optimize the backups so that they do not adversely affect the servers that are hosting the virtual machines.

Disadvantages

You must optimize the parallel backups. The number of virtual machines that you can back up in parallel depends on the following factors:

• The processing power of the server that the IBM Spectrum Protect data mover node runs on.
• The performance of I/O between the client and the IBM Spectrum Protect server.