Resilient File System (ReFS) is a new local file system introduced in Windows Server “8”, immediately addressing critical server customer needs, and providing the foundation for future platform evolution, for all Windows customers.
The main goal behind ReFS is to improve resiliency and reliability, especially in instances when a power failure happens. NTFS could sometimes be corrupted by power failures, and ReFS is specifically designed to protect against that.
ReFS combat bit rot (the corruption of bits in a file system over time) through disk scrubbing tasks that read and validate data. It maintains a high level of compatibility with NTFS and builds on that foundation to be more consistent and never result in downtime. However, ReFS is not supported on removable media and NTFS data can’t be converted. It does not natively offer deduplication, but third-party deduplication software will continue to work.
The Resilient File System relies on the previously existing NTFS code base, although it will not support previous features such as named streams, sparse files, and quotas. ReFS works with Storage Spaces, a system that creates a pool of hardware and virtual storage devices and ensures the protection of data on that system, similar to a RAID array. ReFS will be production-ready when Windows 8 ships, but it can only be used with Windows Server 8 as a storage space. This means a disk formatted with ReFS, in its current state, cannot act as a bootable drive.
Key features of ReFS include:
- Metadata integrity
- Integrity streams
- Copy on write
- Large volume, file and directory sizes
- Storage pooling and virtualization
- Data striping for performance (similar to RAID)
- Disk scrubbing
- Resiliency to corruption
- Compatible with shared storage pools
- NTFS has been enhanced many times and is a perfectly viable file system.
- Refs is actually based on NTFS
- NTFS performed in place updates but made use of a change journal feature.
- ReFS uses allocate on write.
- Allocate on write makes use of integrity streams
- Integrity streams uses allocate on write and check summing.
- Integrity streams can cause problems with large data base.
- ReFS actively searches for volume corruption.
- If corruption is detected then that portion of the volume is isolated against use.
ReFS with VDI
The Refs is designed to work with Windows Storage Spaces, Windows Storage Spaces Creates Virtual disks on top of pools of physical disks. The physical disk can provide redundancy for ReFS.
For Virtual Disks ReFS uses Checksum data to detect Virtual Disk Corruption and if Redundant copies of data exist then each copy is periodically validated.
If corruption is detected then a redundant and healthy copy of data is read from another disk, for Recovery good data is uses to repair corrupt data.
There are also some Limitations on the ReFS file system.
- ReFS cannot be used on boot drive.
- ReFS does not support EFS encryption.
- There is no direct upgrade path from NTFS to ReFS
Differences between NTFS and ReFS
There are, however, certain NTFS features that ReFS does not support. Some of these features are unsupported intentionally.
The following list describes current feature differences between NTFS and ReFS this may change later in the Windows Server “8” release to include additional features:
- Hard Links
- Named Streams
- Extended Attributes (EA’s)
- Object ID’s
- Volume Shrink
- Short Names
- Fast MFT-like Enumeration
- NTFS Compression
- NTFS Encryption
- NTFS Quotas
ReFS Disks Creations on Windows server 8