快速克隆

Fast Clone is the Veeam Backup & Replication technology that helps create quick file copies. Fast Clone increases the speed of synthetic backup creation and transformation, reduces disk space requirements and decreases the load on storage devices.

With this technology, Veeam Backup & Replication references existing data blocks on volumes instead of copying data blocks between files. Data blocks are copied only when files are modified.

Veeam Backup & Replication supports Fast Clone for the following types of backup repositories:

• Linux server
• Microsoft Windows server
• SMB share

Depending on the repository type, Fast Clone uses different technologies and has different requirements and limitations. For more information, see Fast Clone for Linux Repositories and Fast Clone for Microsoft Windows and SMB Repositories.

Veeam Backup & Replication uses Fast Clone for the following operations:

• In backup jobs: merge of backup files, creation of synthetic full backups (including GFS backups), transformation of reverse incremental backups and compact of full backup files.
• In backup copy jobs: merge of backup files, creation of GFS backups (synthetic method) and compact of full backup files.

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

Fast Clone for Linux Repositories

For Linux backup repositories, Fast Clone is based on the reflink technology.

Requirements for Linux Repositories

To use Fast Clone, Veeam Backup & Replication requires that Linux backup repositories meet the following conditions:

• Linux distribution has the reflink kernel module.

Supported distributions: CentOS 8.2 and 8.3, Debian 10.x, RHEL 8.2 or later, SLES 15 SP2, Ubuntu 18.04 LTS and 20.04 LTS. For other distributions, Fast Clone support is experimental.

• File system is XFS.
• Cyclic redundancy check (CRC) is enabled.
• The minimum supported data block size is 1 KB. The maximum supported block size is 4KB.

Configuring a Linux Repository

To configure a Linux backup repository for work with Fast Clone, use the following XFS volume format string:

where:

• size=4096 sets file system block size to 4096 bytes,
• reflink=1 enables reflinking for the XFS instance (disabled by default),
• crc=1 enables checksums, required for reflink=1 (enabled by default).

Limitations

After you have moved backup chains to a Linux backup repository with Fast Clone support, you must create active full backups for these chains to activate Fast Clone. You can also schedule the backup file compact operation instead of active full backup.

Fast Clone for Microsoft Windows and SMB Repositories

For Microsoft Windows and SMB backup repositories, Fast Clone is based on block cloning technology of Microsoft. For more information on block cloning, see Microsoft Docs.

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

Requirements for Microsoft Windows and SMB Repositories

Microsoft Windows Backup Repository

To use Fast Clone, Veeam Backup & Replication requires that Microsoft Windows backup repositories meet the following conditions:

• OS is Microsoft Windows Server 2016 (or later) or Microsoft Windows 10 Pro for Workstations (or later).
• File system is ReFS 3.1 (or later).

Shared Folder Backup Repository

To use Fast Clone, Veeam Backup & Replication requires that SMB backup repositories support FSCTL_DUPLICATE_EXTENTS_TO_FILE and FSCTL_SET_INTEGRITY_INFORMATION. SMB shares configured on Microsoft Windows machines must also support the SMB 3.1.1 protocol and the ReFS 3.1 (or later) file system.

Depending on the type of the performed job, Veeam Backup & Replication also imposes the following requirements on backup infrastructure components.

Limitations

The following limitations apply when Veeam Backup & Replication uses Fast Clone for Microsoft Windows or SMB backup repositories:

• Veeam Backup & Replication does not use Fast Clone for backup repositories configured with Veeam Backup & Replication 9.5 or an earlier version. After upgrade, such backup repositories will work as backup repositories without Fast Clone support. To leverage Fast Clone, edit settings of such backup repositories and complete the Edit Backup Repository wizard without changing settings.
• After you have enabled Fast Clone for existing repositories as described in the previous paragraph or have moved backup chains to backup repositories with Fast Clone support, you must create active full backups for backup chains stored in / moved to the repositories to activate Fast Clone. You can also schedule the backup file compact operation instead of performing active full backup.

• Due to Microsoft limitations, all backup files in the backup chain must be stored on the same volume. For more information, see Restrictions and Remarks at Microsoft Docs.

• 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.
• Veeam Backup & Replication automatically aligns data blocks at a 4KB or 64 KB block boundary depending on the volume configuration or SMB share used storage.

We recommend that you use ReFS volume formatted with 64 KB cluster size to provide better performance with large data volumes.

• When you copy data from a ReFS volume to another location, the file system downloads cloned data blocks. For this reason, copied data occupy more space in the target location than it used to occupy in the source location. This can happen, for example, if you evacuate an extent that supports block cloning from a scale-out backup repository and migrate VM backup data to another extent: copied data will require more space than it originally took.
• If you plan to assign the role of a backup repository to Microsoft Windows Server 2016 version 1709 (or later) or Microsoft Windows 10 Pro for Workstations (or later), mind the following limitations:

• Fast Clone and Windows data deduplication cannot be used simultaneously. Thus, if you target a backup job to a repository supporting Fast Clone and enable Windows data deduplication, the Fast Clone technology will not be used for this job.
• If you target a backup job to a CIFS ReFS repository and enable Windows data deduplication, the job will fail. Veeam Backup & Replication does not support such scenario.

Related Topics

Backup File Placement