Steve Sinofsky in a January 16 blog post authored by Surendra Verma, a development manager on Storage and File System team, shared details about "Protogon," the new file system that the company is developing as part of Windows 8.
Officially named ReFS -- for Resilient File System -- is built on the foundations of NTFS, so it maintains crucial compatibility while at the same time it has been architected and engineered for a new generation of storage technologies and scenarios. It'll become a storage system for Windows clients, and then ultimately "as a boot volume," said Verma.
"In Windows 8, ReFS will be introduced only as part of Windows Server 8, which is the same approach we have used for each and every file system introduction. Of course at the application level, ReFS stored data will be accessible from clients just as NTFS data would be," blogged Verma.
The new file system will be made available via a staged "evolution," according to the blog post.
ReFS is designed to complement the Storage Spaces feature in Windows 8 and Windows Server 8. It'll help with the verification and auto-correction of data and optimize for scale, according to the post.
"Underneath this reused portion (the code responsible for implementing the Windows file system semantics), the NTFS version of the code-base uses a newly architected engine that implements on-disk structures such as the Master File Table (MFT) to represent files and directories. ReFS combines this reused code with a brand-new engine, where a significant portion of the innovation behind ReFS lies," explained Verma.
Some of the key features of ReFS include:
- Metadata integrity with checksums
- Integrity streams providing optional user data integrity
- Allocate on write transactional model for robust disk updates (also known as copy on write)
- Large volume, file and directory sizes
- Storage pooling and virtualization makes file system creation and management easy
- Data striping for performance (bandwidth can be managed) and redundancy for fault tolerance
- Disk scrubbing for protection against latent disk errors
- Resiliency to corruptions with "salvage" for maximum volume availability in all cases
- Shared storage pools across machines for additional failure tolerance and load balancing
ReFS comes with a series of features that are also present in NTFS including: BitLocker encryption, access-control lists for security, symbolic links, junction points, volume snapshots, file IDs, and more.
Microsoft has also ensured that all data stored on ReFS is currently accessible through the same file access APIs on all clients and platforms that can now access NTFS volumes.
Along with Storage Spaces, ReFS forms the foundation of storage on Windows for the next decade or more. Together, Storage Spaces and ReFS have been architected with headroom to innovate further, Verma added.
Here are the capacity limits of ReFS: