VEEAM 9.5 ReFS Integration

Share This Post

Veeam v9.5 was recently released and with it came a large number of improvements and added features. Namely, the seamless integration of Microsoft Server 2016’s new ReFSv3.1 filesystem. Veeam’s integration with this version of ReFS adds the fast cloning ability and spaceless full technology, meaning merges and synthetic operations require less resources and time and synthetic full backups take up significantly less storage.

Veeam 9.5 ReFS Benefits

Veeam 9.5 integration with Windows server 2016 ReFS comes with 2 significant benefits to synthetic and merge operations: Fast Cloning and Spaceless Full Technology.

Both of these rely on Veeam v9.5’s integration with ReFS allowing Veeam to utilize ReFS block cloning. This allows Veeam backups to copy data blocks within files or even from one file to another very quickly. When data is copied, the file system will not create new copies of existing data blocks and instead creates pointers to the locations of existing data.

–Fast Cloning with ReFS ensures that because new full backups do not need to copy existing data and instead use pointers to existing backup data it significantly reduces the time required to perform synthetic operations which can normally be very resource intensive.

–Space-less Full Backups are possible due to the fact that new synthetic backups are primarily made up of pointers to existing full backup data, significantly reducing the space required to store the backups.

One of the downsides of space-less fulls when compared to a deduplicating storage device is that there is no global ded uplication. Space-less fulls with ReFS will only reduce storage usage between copies of the same full backup file. Even still however, the space savings are tremendous:


In the picture above we moved a customer with close to 1TB native backup size from an NTFS backup repository to an ReFS repository. After a month of weekly and monthly GFS backup copies the utilized storage is less than half of the native file size. The customer already had full backups, and as those older GFS restore points get removed due to retention and replaced with ReFS spaceless fulls the utilized storage will continue to decrease.

–Encryption is also possible with ReFS space-less fulls. One of the downsides of deduplication is that backup files cant be encrypted otherwise you lose the benefits of deduplication. Because the space-less fulls and encryption are both transparent to Veeam, it’s able to both encrypt the data while still providing the space saving benefits of space-less full backups on ReFS.

Adding ReFS Volumes as Veeam Repositories

In order to see the benefits of ReFS with Veeam older repositories will need to be attached to a Windows Server 2016 server and formatted as ReFS. If you had previously added a Windows Server 2016 ReFS volume as a repository, it will need to be readded after upgrading to Veeam v9.5 in order for Veeam to recognize it as an appropriate ReFS volume and allow the new features to be utilized.

Important: Veeam’s fast cloning and spaceless full technology only supports ReFS volumes created on Windows Server 2016, volumes formatted as ReFS in Windows Server 2012 will not see the benefits because Server 2012 uses an older version of ReFS.

Any restore points created prior to the v9.5 upgrade will not see the new benefits. In order to utilize fast cloning and spaceless fulls, all full and incremental backups involved in synthetic operations will need to have been created using Veeam v9.5 with a Windows Server 2016 ReFS repository. This means the benefits of fast cloning and spaceless fulls will not apply when you first copy older backup data into the new ReFS repository.

Therefore, in order for existing backup or backup copy chains to begin seeing these benefits, either an active or synthetic full(including backup copy Synthetic GFS) will need to be performed. Then the next time a synthetic operation is performed the [fast clone] tag will be displayed next to the synthetic operation in the job activity logs, as well as a corresponding increase in the speed of the operation.

Update: Make sure to use 64K Block Size when formatting the Veeam repository volumes to avoid issues with 4K Block Size and ReFS. Read this post for more information.

Interested in learning how Managecast can help your business with its cloud backup and disaster recovery solutions? Fill out this form for more information!

More To Explore