Though it's (as usual) been overshadowed by the just-released Windows 8 client, the Windows Server 8 beta has also just been made widely available. Now the world can kick the tires of this massive update to the foundation of the Windows environment.
Windows IT Pro authors have written a number of articles about the many different aspects of Windows Server 8, so if you haven't been keeping up with all the updates to this OS, you should have a look.
With this beta, Microsoft has addressed bugs since the Developer Preview, increased the fit and finish of literally thousands of features (the reviewer's guide covering only the top features is over 200 pages long), and added a few new features. Microsoft vice president Bill Laing reviews all the new features in his blog post on the Windows Server blog, but I wanted to point out a significant new arrival.
This beta marks the introduction of Resilient File System (ReFS), the successor to the venerable NT File System. The NT name alone reveals how long this file system has been around: almost 20 years. ReFS was engineered to meet four design pillars- , data integrity, availability, scalability, and application compatibility. ReFS is designed to keep data available despite errors that would, in NTFS, cause data loss or downtime. Additionally, it's designed to keep this availability on low-cost, commodity hardware (such as SATA) that doesn't have traditional reliability of enterprise storage. This reflects experience in massive cloud storage where arrays of inexpensive drives are used and component failure isn't just tolerated; it's expected.
ReFS scales to support petabyte-sized (1000 terabytes) volumes. Specifically, the ReFS on-disk format is designed to support volume sizes up to 2^78 bytes using 16KB cluster sizes while Windows stack addressing allows 2^64 bytes. This format also supports 2^64-1 byte file sizes, 2^64 files in a directory and the same number of directories in a volume.
Some NTFS features won't make it to ReFS
ReFS will be mostly backward compatible with NTFS. Some features that Microsoft describes as "having limited value" - compression, for example - won't be supported, so you're going to need to review your current volume configurations to determine whether you should be concerned . You can read a detailed architectural post about ReFS on the Building Windows 8 blog.