The Resilient File System (ReFS) will make its first appearance as a storage system in Windows Server 8, after which it will evolve into a system for client storage, then ultimately for boot volumes.
On Monday, Microsoft used a post on its Building Windows 8 blog to lay out details on ReFS.
“Along with Storage Spaces, ReFS forms the foundation of storage on Windows for the next decade or more,” Microsoft development manager Surendra Verma wrote. “We believe this significantly advances our state of the art for storage… we expect that we will see ReFS as the next massively deployed file system.”
The “staged evolution” of ReFS, beginning with its use as a file server, is the same approach Microsoft has taken with previous file systems.
According to Verma, ReFS has many of the same features and semantics as NTFS, which was introduced in 1993. These include “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”. If a file-access API can access an NTFS volume, it will be able to access data stored on ReFS. What has changed is the on-disk storage engine underneath the reused code.
The ReFS engine exclusively uses the so-called B+ tree structure to represent stored information. Verma indicated this will mean a simpler system, with the choice of structure designed to be as scalable as possible. When ReFS is used alongside mirrored Storage Spaces, corruptions will be “automatically and transparently fixed”, Verma added, noting that ReFS also had a ‘salvage’ feature for making sure that non-repairable corruption does not affect the availability of “good data”.
Responding to readers’ questions about the blogpost, Verma also stressed that Windows 7 users would be able to read ReFS-formatted partitions from a Windows 8 Server, either by using a new file system driver or by sharing a folder out from the server. “Note that support for NTFS is going to be present in Windows for the foreseeable future, so you should always be able to access all your NTFS data across versions without any problems,” he added.