Microsoft Outlines Details of New Windows File System
Microsoft has outlined details of its next-generation file system, which will make its debut in Windows Server 8. The new Resilient File System, or ReFS, will succeed the long-established New Technology File System (NTFS), first introduced with Windows NT and later Windows XP.
It is Microsoft's first major new Windows file system in nearly two decades and is designed to take advantage of new storage architectures, the use of metadata and virtualization.
Microsoft outlined technical details and its roadmap for ReFS in a post on its Building Windows 8 Blog on Monday. ReFS will be compatible with NTFS but is designed to provide higher levels of resilience and scalability.
ReFS will take advantage of Storage Spaces, the storage aggregation feature that Microsoft is introducing for Windows 8, detailed earlier this month. Storage Spaces, which will also work with NTFS, will let users virtualize pools of hard disk drives and solid state drives.
Surendra Verma, a development manager with Microsoft's storage and file system team, underscored in the blog post that the company built ReFS in conjunction with Storage Spaces to allow for large volume, file and directory sizes, simplified storage pooling and virtualization within the file system, and better resilience to corruption and failures with large volumes and shared storage pools.
"Data stored on ReFS is accessible through the same file access APIs on clients that are used on any operating system that can access today's NTFS volumes," Verma noted. "In addition, ReFS inherits the features and semantics from NTFS including BitLocker encryption, access-control lists for security, USN journal, change notifications, symbolic links, junction points, mount points, reparse points, volume snapshots, file IDs and oplocks."
Microsoft didn't start from scratch when developing ReFS but rather extended NTFS, according to Verma. The team reused code that implements the Windows file system semantics, including read, write, open close and change notification. It also "maintains in-memory file and volume state, enforces security, and maintains memory caching and synchronization for file data. This reuse ensures a high degree of compatibility with the features of NTFS that we're carrying forward," Verma explained.
ReFS is designed to maximize disk reliability with a new transactional model and resiliency to disk corruption, integrity streams designed to protect files from data corruption, Verma added.
In keeping with Microsoft's past release of new file systems, ReFS will debut with Windows Server 8. The company will later add it to the client and finally as a boot volume. However NTFS-based clients will be able to access ReFS data via the file-level APIs that can access NTFS volumes. Verma didn't reveal rollout details.
Like NTFS and its predecessor the File Allocation Table (FAT), ReFS will not allow users to convert data among the different file systems. Users will not be able to implement ReFS on removable drives. It also will support failover clustering.
Jeffrey Schwartz is editor of Redmond magazine and also covers cloud computing for Virtualization Review's Cloud Report. In addition, he writes the Channeling the Cloud column for Redmond Channel Partner. Follow him on Twitter @JeffreySchwartz.