Resilient File System (ReFS) is a Microsoft proprietary file system introduced with Windows Server 2012 with the intent of becoming the “next generation” file system after New Technology File System (NTFS).
Microsoft’s new ReFS file system was originally introduced on Windows Server 2012. Although, the initial version removed some of NTFS’ features such as disk quotas, alternate data streams, and extended attributes. Some of these were re-implemented in later versions of ReFS.
ReFS does support some NTFS features like sparse files, reparse points, case-sensitive file names and Unicode in file names and, perhaps most important, it preserves and enforces access control lists (ACLs).
Many NTFS disk tools don’t work with ReFS because it handles the file metadata differently. Like its predecessor, ReFS began as a file server system, then became a mainstream file system. While ReFS may appear to have some similarity to NTFS, it does not contain all the primary NTFS features. It has its own advantages and disadvantages.
It scales proficiently to handle a larger data set than NTFS. So, ReFS is not a replacement for NTFS rather it is intended to be used in specific circumstances mainly for storage of very large data sets.
Why Should you Consider ReFS?
In fact, there are many benefits to using ReFS but the main reason comes from the two main changes in storage systems and technique.
Can be used with large size storage, and large arrays of multi-terabyte drives or storage space
For example, using ReFS with Storage Spaces is a good match. It is not necessary to use ReFS on Storage Spaces but using it will definitely provide supported benefits since it has its own mechanism of metadata checksum. ReFS uses its own checksums on the metadata to ensure that the data has not been corrupted. It can detect and repair the problems.
Storage Spaces uses mirroring, to spread copies of data across multiple physical data drives. When storage space finds a problem with a piece of corrupt data on a drive, the corrupted data will be removed from the drive and replaced with a good copy of the data from another one of the physical drives. When storage space finds mismatched data between two or more copies of the same file, it can rely on the built-in mechanism of ReFS’ metadata checksums. Once the checksums are validated, the correct data is copied back to the other physical drives and the corrupted data is removed.
ReFS routinely performs “Scrubbing” where it checks the data pieces using its checksum on every file used in Storage Spaces and if there are any checksums that are found to be invalid, the corrupted data is replaced with good data from a physical drive that has a valid checksum. Scrubbing is on by default, but it can also be customized to configure on specific files.
Its reliable, and it verifies and auto-correct data
Unlike NTFS, ReFS is more reliable and much less likely to experience problems when volume is corrupted. Even with or without mirroring or Storage Spaces, only the corrupted parts of volume gets detected and removed. Once the corrupt data is removed the volume is brought back in a matter of seconds. This concept is considered “salvage” for maximum volume availability in all cases.
Allocation-on-write update strategy for metadata
There is less risk that data will be lost when there’s a power failure due to the way it writes metadata.
Supports Long File Names and File Path
A file name in ReFS can be up to 32,768 Unicode characters which is considerable longer than NTFS’ 255 characters.
Full path size has also been updated from 255 characters to 32K.
It supports a maximum volume size of one yottabyte and a single file can weigh up to 16 exabytes.
Better performance with ReFS.
In 2016 ReFS, with certain VM features, better performance can be achieved for Microsoft virtualization Hyper-V from ReFS “block cloning” and “sparse VDL” features.
What missing in ReFS?
Microsoft made ReFS largely compatible with NTFS but it didn’t implement all its features. Here’s a list of some of the features that are not included:
1. No Disk Quotas
2. No EFS encryption
3. No support for Object Identifiers
4. Doesn’t support Extended Attributes
5. No File-based Compression
6. No support for Hard Links, which means it doesn’t support the operating system (OS) and some applications.
7. Windows cannot be booted from a ReFS volume.
8. No conversion capability between NTFS and ReFS.
9. No file-based deduplication.
10. No support for DOS-style 8.3 filenames. On an NTFS volume, but we can still access C:\Program Files\ at C:\PROGRA~1\ for compatibility purposes with old software. These legacy file names are gone on ReFS.
Without a doubt, ReFS is a most robust file system in terms of its data reliability and metadata improvements. So far, Microsoft has begun the process of improving file systems with the newer versions with added benefits.
Just like NTFS, these improvements with ReFS will soon become popular and our new normal standards in the future.
Vikram Singh is the Server Support Specialist at Triella, a technology consulting company specializing in providing technology audits, planning advice, project management and other CIO-related services to small and medium sized firms. For additional articles, please visit http://www.triella.com/whats-new/. Triella is a VMware Professional Partner, Microsoft Certified Partner, Citrix Solution Advisor – Silver, Dell Preferred Partner, Authorized Worldox Reseller and a Webroot Reseller.
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