What Is ReFS (the Resilient File System) on Windows?


Microsoft’s new ReFS file system was originally introduced on Windows Server 2012. It’s included on Windows 10, where it can only be used as part of the drive-pooling Storage Spaces feature. ReFS will be improved in Windows Server 2016, and a leak from Microsoft indicates that it will be part of a new edition of Windows 10, named Windows 10 Pro for Advanced PCs.

But what is ReFS, and how does it compare to the currently-used NTFS?

What Is ReFS?

Short for “Resilient File System”, ReFS is a new file system built using code from the current NTFS file system. At the moment, ReFS is not just a replacement for NTFS. It has its own advantages and disadvantages. You can’t just use ReFS instead of NTFS on your system drive.

As ReFS is Microsoft’s newest file system, it’s designed to address a few major issues with NTFS. ReFS is designed to be more resilient against data corruption, perform better for certain workloads, and scale better for very large file systems. We’ll look at exactly what that means.

ReFS Protects Against Data Corruption

The “Resilient” part is highlighted in the name. ReFS uses checksums for metadata—and it can optionally use checksums for file data, too. Whenever it reads or writes a file, ReFS examines the checksum to ensure it’s correct. This means the file system itself has a built-in way to detect data corruption on the fly.

ReFS is integrated with the Storage Spaces feature. If you set up a mirrored Storage Space using ReFS, Windows can easily detect file system corruption and automatically repair problems by copying the alternate copy of the data on another drive. This feature is available on both Windows 10 and Windows 8.1.

If ReFS detects corrupted data and doesn’t have an alternate copy it can restore from, the file system can immediately remove the corrupted data from the drive. It doesn’t require you reboot your system or take the drive offline, as NTFS does.

ReFS doesn’t just check files for corruption when reading and writing them. An automated data integrity scanner regularly checks all files on the drive to identify and fix data corruption, too. It’s an auto-correcting file system. You don’t need to use chkdsk at all.

The new file system is also resistant to data corruption in other ways, too. For example, when you update a file’s metadata—the file name, for example—the NTFS file system will directly modify the file’s metadata. If your computer fails or the power goes out during this process, there may be data corruption. When you update a file’s metadata, the ReFS file system will create a new copy of the metadata. ReFS points the file at the new metadata only after the new metadata is written. There’s no risk of the file’s metadata being corrupted. This is known as “copy-on-write”. Copy-on-write is also available on other modern file systems, like ZFS and BtrFS on Linux as well as Apple’s new APFS file system.

ReFS Drops Some…

Sasha Harriet

Sasha Harriet

As content editor, I get to do what I love everyday. Tweet, share and promote the best content our tools find on a daily basis.

I have a crazy passion for #music, #celebrity #news & #fashion! I'm always out and about on Twitter.
Sasha Harriet

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