NTFS versus Resilient File System (ReFS)
Before talking about Storage Spaces, I'd like to discuss ReFS. Currently Hyper-V supports two filesystems, the classic NTFS, and the more recent Resilient File System (ReFS). Before Windows Server 2016, I recommended that you use NTFS, because ReFS had a lack of some key capabilities and most backup applications have problems with it. Now in Windows Server 2016, Microsoft brings a lot of new features in ReFSv2 as the Accelerated VHDX Operations. The capability enables us to accelerate operations during the following scenarios:
Creating and extending a virtual hard disk
Merging checkpoints
Backups, which are based on production checkpoints (we will discuss production checkpoints later in this chapter)
When you extended a VHD(X) located in an NTFS partition, the system was written by zeroing out the new block. In ReFS, the new blocks are metadata instead. Thanks to ReFS, now you just need between 1 to 5 seconds to create a big VHDX instead of many minutes...
