Microsoft this week revealed that it would introduce a next-generation file system to replace NTFS in Windows 8.
As it has done with new file systems in the past, Microsoft (NASDAQ:MSFT) said it will stage the introduction Resilient File System (ReFS) — it will initially debut as part of Windows Server 8, but will eventually be introduced as storage for clients and ultimately as a boot volume.
"Today, NTFS is the most widely used, advanced and feature-rich file system in broad use," Steven Sinofsky, president of the Windows and Windows Live Division at Microsoft, wrote in a blog post Monday. "But when you're reimagining Windows, as we are for Windows 8, we don't rest on past successes, and so with Windows 8 we are also introducing a newly engineered file system. ReFS (which stands 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."
While ReFS will initially only be available for storage on Windows Server 8, Sinofsky said ReFS stored data will be accessible from clients on the application level, just as NTFS data would be.
Surendra Verma, a development manager on the Storage and File System team at Microsoft, said the team has five key goals for ReFS, as follows:
- Maintaining a high degree of compatibility with a subset of NTFS features that are widely adopted, while at the same time deprecating features that provide limited value at the cost of system complexity and footprint
- Supporting the ability to verify and auto-correct data
- Optimizing for extreme scale, with scalable structures for everything
- Never taking the file system offline; instead it will isolate faults while allowing access to the rest of the volume and salvaging the maximum amount of data possible
- Providing a full end-to-end resiliency architecture when used in conjunction with the Storage Spaces feature, co-designed and built in conjunction with ReFS
"Along with Storage Spaces, ReFS forms the foundation of Windows for the next decade or more," Verma said. "We believe this significantly advances our state of the art for storage. Together, Storage Spaces and ReFS have been architected with headroom to innovate further, and we expect that we will see ReFS as the next massively deployed file system."
Verma said the key features of ReFS, some of which are provided in conjunction with Storage Spaces, include:
- Metadata integrity with checksums
- Integrity streams providing optional user data integrity
- Allocate on write transactional model for robust disk updates (copy on write)
- Large volume, file and directory sizes
- Storage pooling and virtualization that simplifies file system creation and management
- Data striping for performance 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
Verma said Microsoft has tested the file system using a set of tens of thousands of tests it developed over the past two decades for NTFS. Noting that the tests simulate and exceed the requirements of the deployments Microsoft expects in terms of stress on the system, Verma said ReFS is ready to be deployment-tested in a managed environment.
"Initially, our primary test focus will be running ReFS as a file server," Verma said. "We expect customers to benefit using it as a file server, especially on a mirrored Storage Space. We also plan to work with our storage partners to integrate it with their storage solutions."