First Look: Microsoft’s Reliable File System Version 2
When Microsoft introduced its new on-disk file system with Windows 8 and Windows Server 2012, it wasn’t meant to replace NTFS in its initial release. The Reliable File System, or ReFS, still isn’t ready to completely take over as the default unless you need a data store meant to support Windows Hyper-V disk images. In that case, Microsoft really does want you to use the next iteration of the file system – ReFS v2 – as it offers a number of advantages and advancements with significant performance improvements.
Storage Spaces was also a part of the Windows 8/Windows Server 2012 release and provides multi-disk file resiliency, which is essentially software RAID. Storage Spaces offers three options: simple, mirror and parity. Simple provides no file resiliency and is roughly equivalent to RAID 0 on a single disk. Mirror is basically the same as RAID 1 and creates an exact copy of all data on two or three physical disks. Parity is essentially equivalent to RAID 5 and distributes data across multiple disks using parity as a way to detect errors. Storage Spaces will work with either NTFS or ReFS as the on-disk format.
ReFS v1 included a design feature called integrity streams that makes it possible to detect and correct file system corruption on the fly. Unfortunately, this feature didn’t play well with Hyper-V virtual disks and could significantly impact performance. The work around is to disable this feature for both Windows Server 2012 R2 and the technical preview (TP) versions of Windows Server 2016. The process for creating a new ReFS volume hasn’t changed (see Figure 1) and happens during the new volume creation process. ReFS v2 will be used automatically if you’re running Windows Server 2016 TP4.