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Is Microsoft ReFS a replacement for data backup?

While Microsoft ReFS can improve data integrity, it is not an alternative to data backup. Expert Brien Posey explains some of the key features of the file system.

The Microsoft Resilient File System (Microsoft ReFS) is a Windows file system that was first introduced with Windows Server 2012. It was designed to be a next-generation replacement for the NTFS that has been a part of Windows Server for approximately 20 years. Although ReFS includes some mechanisms to help preserve the integrity of your data, it was never intended to be a backup replacement.

ReFS is designed to automatically detect instances of corruption and repair the corruption whenever possible. To accomplish these tasks, the Microsoft ReFS formatted volume must reside on top of a virtual disk hosted on Windows Storage Spaces.

Microsoft ReFS uses several different techniques to safeguard file system data. All the ReFS metadata has a 64-bit checksum that is stored independently of file data. In addition, the file system can have its own checksum that exists in a separate integrity stream. ReFS can automatically check data integrity by examining this checksum data. Previous file systems, such as NTFS, required administrators to manually run CHKDSK or similar utilities to test disk health. With ReFS, CHKDSK becomes unnecessary.

The file system's "allocate on write" feature also helps to preserve data integrity. If a user updates an existing file, most file systems would write the new data on the top of the old data. The problem with this approach is that if the write operation were to fail, the previous version of the file would be damaged. Microsoft ReFS uses available storage blocks for update writes rather than immediately overwriting existing data. This preserves existing data in the event of a failure.

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