We've heard about Microsoft's Windows 8 Resilient File System (ReFS) before, but Microsoft revealed the specifics of its next-generation file system in full today. Microsoft's "designed from the ground up" ReFS has been created to meet today and tomorrow's needs for Windows storage — the ability to handle large volumes, resiliency to corruption, and shared storage pools across machines. ReFS will only be available inside Windows Server 8, so the vast majority of Windows 8 users will not benefit from its improvements at launch — Microsoft has plans to test it fully before making it available to Windows 8 client users.
ReFS simply plugs into the storage stack like any existing file systems, and is built on the foundations of NTFS to maintain elements of compatibility. ReFS and Storage Spaces, a feature Microsoft detailed recently, were forged to complement each other for a complete storage system overhaul in Windows 8. The main advantages of the new file system include the ability for Windows 8 to detect all forms of disk corruption, data striping support for performance, and an allocate on write model known as copy-on-write. Microsoft has used copy-on-write (COW) concepts in its SQL Server products and Volume Shadow Copy Service previously, enabling quick snapshots of large data sets.
ReFS cannot be used on removable media, nor can it be used to boot an operating system — it's simply for storage right now. Microsoft says the new file system will only be introduced as part of Windows Server 8, but Windows 8 client will be able to access and read ReFS volumes until it's fully supported in client operating systems in the future. If you want the full lowdown on ReFS then hit the source link for a detailed explanation from Microsoft's Storage and File System team.