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Veeam Backup & Replication 9.5
User Guide for Microsoft Hyper-V

Fast Clone

To enhance synthetic operations on Microsoft Windows and shared folder backup repositories, Veeam Backup & Replication uses the Fast Clone technology. Fast Clone lets you create synthetic full backups and GFS backups without moving data blocks between files. Instead, Veeam Backup & Replication leverages the spaceless full backup technology and references data blocks that are already present on the volume. Fast Clone increases the speed of synthetic backup creation and transformation, reduces disk space requirements and load on the storage devices.

Fast Clone is based on Block Cloning. Block Cloning is Microsoft functionality available on ReFS 3.0. Block Cloning allows applications to quickly copy data blocks between different files or within the limits of one file. When an application needs to copy data, the file system does not physically copy data on the underlying storage. Instead, it performs a low-cost metadata operation — it ‘projects’ data blocks from one region on the ReFS volume to another one.

Block Cloning increases data copying performance as the file system does not need to read/write data from/to the underlying storage. It also helps reduce the amount of redundant data. For more information, see https://msdn.microsoft.com/en-us/library/windows/desktop/mt590820(v=vs.85).aspx.

Backup Repository Configuration

To configure a backup repository with Fast Clone support, you must assign the role of a backup repository to a Microsoft Windows 2016 Server or shared folder SMB 3.11. Veeam Backup & Replication automatically detects if the server or shared folder meets the specified requirements and if Fast Clone can be used for work with data stored on this backup repository.

Fast Clone requires that the starting and ending file offsets are aligned to cluster boundaries. For this reason, Veeam Backup & Replication automatically enables the Align backup file data blocks option for backup repositories that support Fast Clone. Data blocks are aligned at a 4KB or 64 KB block boundary, depending on the volume configuration.

Fast Clone 

Veeam Backup & Replication supports Fast Clone on all types of backup repositories: simple, scale-out and cloud. Fast Clone works on backup repositories that meet the following requirements:

Microsoft Windows Backup Repository

  • OS: Microsoft Windows 2016 Server
  • File system: ReFS 3.x

Shared Folder Backup Repository

Type of Job/Task

Requirements to backup infrastructure components

Backup job

Protocol: SMB 3.11

OS: Microsoft Windows 2016 on the following backup infrastructure components:

  • Manual gateway selection: Gateway server.
  • Automatic gateway selection:
    [For forward incremental chains] Mount server associated with the backup repository, or backup server.
    [For reverse incremental chains] Fast clone is supported if the source host runs Microsoft Hyper-V Server 2016. For earlier versions of hypervisor, fast clone is not supported.

Backup copy job

Protocol: SMB 3.11

OS: Microsoft Windows 2016 on the following backup infrastructure components:

  • Manual gateway selection: Gateway server.
  • Automatic gateway selection:
    [For direct data transport path] Mount server associated with the backup repository, or backup server.
    [For data transport path over WAN accelerators] Microsoft Windows 2016 on the target WAN accelerator.

Mind the following:

  • By default, Veeam Backup & Replication uses Fast Clone for all backup repositories that meet the specified requirements. You can disable this option with a registry key. For more information, contact Veeam Support Team.

Operations with Fast Clone

Veeam Backup & Replication leverages Fast Clone for the following synthetic operations:

In backup jobs:

  • Merge of backup files
  • Synthetic full backup
  • Reverse incremental backup transformation
  • Compact of full backup file

In backup copy job:

  • Merge of backup files
  • Creation of GFS backups (synthetic method)
  • Compact of full backup file

When Veeam Backup & Replication performs a synthetic operation with Fast Clone, it reports this information to the session details for this operation. 

Limitations for Fast Clone

  • Veeam Backup & Replication does not use Fast Clone for backup repositories configured with previous versions of the product. After upgrade, such backup repositories will work as backup repositories without Fast Clone support. To leverage Fast Clone, you must remove such backup repositories from the backup infrastructure and add them once again.
  • Fast Clone requires that source and destination files are stored on the same ReFS volume. If you add a backup repository with Fast Clone support as an extent to a scale-out backup repository, make sure that you enable the Data Locality placement policy for this scale-out backup repository. If backup files are stored on different extents, Fast Clone will not be used.
  • If you move backups to a backup repository with Fast Clone support, you must perform active full backup for all existing backup chains (manually or automatically by schedule). You can also schedule the backup file compact operation instead of active full backup.
  • Veeam Backup & Replication enables the Align backup file data blocks option for backup repositories with Fast Clone support after backup repositories are created. When you pass through the New Backup Repository wizard, the Align backup file data blocks check box will not be selected.

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