Microsoft is testing Insider builds that use the modern ReFS file format instead of the more common NTFS for a clean installation of Windows 11. When you install a supported version of Windows using an ISO or from a USB drive, you can choose ReFS or the default NTFS format when you reach the “setup” screen, where you enter the region and language and your license key. While not explicitly mentioned in Microsoft’s release notes for Insider build 27823 (Canary), PhantomofEarth on X noticed this Flexible Storage option.
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3 What is the ReFS File System?
A file system that’s resilient from data corruption and responsive
ReFS stands for “Resilient File System.” It has been used for secondary drives, starting with Windows 8. However, it hasn’t been available as part of a bootable Windows drive. However, it looks like that might be changing with a rebirth through a Flexible Storage option.
The new file system promises to fix problems with the “NT File System” (NTFS), including data corruption protection, improved workload performance, and scalability on large volumes. Checksums for metadata and file data achieve better resilience.
When a ReFS-formatted drive reads or writes files, it examines the checksum to ensure accuracy. The idea is to detect corruption in your drive for corruption in real time. It is also integrated with Windows 11’s Storage Spaces feature. With ReFS, Windows can detect data corruption and repair issues by copying alternative data copies of files on a separate drive. In addition to checking for data corruption, an automated data integrity scanner fixes the corruption. So, it is an auto-correcting file system that protects your data more proactively than NTFS. A drive formatted with ReFS could render disk-checking utilities like the built-in chkdsk tool obsolete.
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2 Could ReFS replace NTFS?
It’s a good possibility, but there are drawbacks
NTFS is a widely available file system and has been the standard for Windows systems. It is proven to have many benefits, such as larger volume sizes — up to 256TB — stability, BitLocker encryption, and removable drive support. ReFS, conversely, isn’t widely available, boot media isn’t supported (you can't boot into Windows from it), file system compression isn't available, and storage isn’t entirely stable. It’s also worth noting that a ReFS volume can be accessed by other OSs formatted with NTFS. It's also important to note that legacy OS compatibility issues could exist. For instance, Windows 7 or 8 can't use it without several registry tweaks, and Windows 10 and 11 also have difficulties with it on older systems. Also, we can expect certain apps to have incompatibilities with the file system.
1 NTFS is key for now
But ReFS is waiting in the wings
For now, the NTFS file format is the gold standard when installing Windows. When you purchase a new PC, it is formatted as NTFS by default and often has BitLocker enabled by default. Even though ReFS can handle data more efficiently than large-capacity drives, you will still want to keep NTFS in place for now. In fact, the modern ReFS file format for local drives is being tested and is only available in select early Windows Insider builds. It is only accessible when you run a clean installation of Windows 11 from an ISO or USB drive during the initial setup experience.
Even with the availability of the option, you can’t yet boot from it. For now, you need to install Windows on an NTFS partition, like usual, and boot it up. Then, you can manually set up ReFS on a separate partition.
NTFS has been the primary file format for Windows PCs for over thirty years, replacing the FAT file system. Since Windows 2000, NTFS has been the standard. It is durable, reliable, and can adapt to constantly changing Windows versions and features. However, it could be time for a change. Like NTFS replacing FAT, the ReFS file format could be the new standard for modern Windows systems and replace NTFS.
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Could ReFS replace NTFS in the future (maybe)
The company appears to be testing ReFS, but Windows cannot be booted directly from a drive formatted with it. However, it seems to be part of the broader Flexible Storage approach, which could mean differently formatted drive pools. For instance, 4TB laptops could become the norm with an NTFS partition to boot from Windows and a ReFS partition that can be used for massive amounts of data.
It’s also important to note that just because a feature is included in a beta version of Windows, it doesn’t guarantee it will be in the final release. However, there is a pretty good bet that ReFS will be. Whether it will be the default and fully replace NTFS on Windows remains to be seen. The company is testing it out now to work out the bugs. ReFS will probably be in future Windows builds until it officially becomes available. Perhaps as soon as the upcoming 25H2 feature update? If not, you can assume it will be next year or part of Windows 12.