ReFS File System

What is ReFS

ReFS, an acronym for Resilient File System, is a next-generation file system created by Microsoft. When the filesystem is released it is to be used on Windows 8 Servers and later on all the other home PCs running Windows 8. This filesystem was developed from the ground but, nevertheless, provides partial compatibility with NTFS. ReFS has inherited the most useful features from NTFS while rejecting those that do not meet both the developers and users expectation like multiple data streams or hard links.

The ReFS filesystem was designed as a filesystem which would be used on a large storage. A side effect of this is that you cannot use ReFS on a removable storage. Another consequence is that ReFS widely uses B-tree data structures, which are known to be bulky, to get better performance. Additionally, ReFS is expected to provide better protection against data loss due to various reasons and to ensure greater resistance to omnifarious failures.

Symptoms of ReFS failure

Although ReFS is introduced as a filesystem which resists to various failures, nevertheless, practice shows that ReFS does fail. In those cases when an operating system cannot access the data on a ReFS volume, you see the following error message stating that the volume is not accessible and the volume repair was not successful:

You receive the same error message if the filesystem driver tried to read the data, encountered an error, and was not able to correct it. It results in an "isolation" of a failed part which is an euphemism to the loss of data. Additionally, if you try to start CHKDSK on a ReFS volume, you get the message:

The type of the filesystem is ReFS.
The ReFS file system does not need to be checked.

As it is known, ReFS is a filesystem which is capable of checking and correcting errors whenever possible. If the ReFS driver encounters an error, for example if checksums don't tally with the data, the driver corrects the error based on the second copy of the data in case of a mirrored storage. If the storage is not mirrored or if the driver cannot correct the error using the second copy, the driver corrects the error as best it can.

Thus, due to the peculiarities of ReFS, algorithms implemented in the NTFS version of CHKDSK to check filesystem integrity, cannot be used in ReFS. The algorithm of ReFS integrity checking has to read all the data from the volume. All this along with the fact that ReFS was designed as a filesystem for a large storage caused the ReFS designers to abandon the idea of adapting CHKDSK to ReFS.

ReFS recovery

If ReFS fails beyond the driver capability to recover it, you need a data recovery software to try and get data from the failed volume. Read more on ReFS recovery software and specifics.