Sun's ZFS was the first 21st century file system (see ZFS: threat or menace? for a detailed overview) that focused on data integrity and operational simplicity. ReFS steals several pages from the ZFS playbook.
Don't get too excited though: like most major FS introductions, this one is server only, and won't, initially, support booting. Think of it as an extended beta that, after a year+ of baking, will come to the rest of us.
Combined with Windows 8 Storage Spaces, ReFS provides a strong foundation for the next 20 years of Windows data management.
What's in ReFS?
According to a recent Microsoft blog post, ReFS stands for Resilient File System. It's an honest attempt to deal with NTFS's well-documented data integrity issues that Storage Bits discussed over 4 years ago.
Some key features:
- Good compatibility with NTFS. The team sought to ensure that the most-used NTFS functionality was supported, but some capabilities - object IDs, compression, file level encryption and quotas among them - won't be.
- Robust disk updates. Instead of updating metadata in place, ReFS writes updates to a different location atomically. Keeps metadata valid despite power failures or hardware issues.
- Check-summed metadata. Detects all forms of disk corruption, including lost and misdirected writes and bit rot.
- Scalable. ReFS uses highly-scalable B+ tree based on-disk structures to enable both very large files - 2^64-1 bytes - directories - 2^64 files - and volumes - 2^64 bytes.
- Very long file names. Up to 32k characters.
There's much more, but we'll have to wait to see how Windows 8 Server acceptance shakes out before we'll know how soon desktop users will see them.
ReFS is designed to work with - if/when it is available - Windows 8 Storage Spaces. Even without ReFS, W8SS is pretty cool. But that's for another post.
The Storage Bits take
I agree with my ZDNet colleagues that Windows 8 will be dead on arrival. There are just too many changes for the massive Windows app world to handle in a year or two. ReFS is one of those.
But whether intentionally or not, treating W8 as a foundational release - much as Apple treated Mac OS 10.6 Snow Leopard - is a smart move. Windows has been groaning under the weight of a too-strong committment to backwards compatibility - and the 1980's technology that entails.
NTFSs many problems make it a prime candidate for a deep renewal. My only concern is that 5 years from now the team - and us users - might be wishing they'd been more bold in dumping NTFS interfaces, not less.
But now is the time for Mac fans to take notice: ReFS and W8SS are fully competitive with where Apple could have been last year. Apple has punted on data integrity, and Mac users will suffer.
But it's not too late for Apple: they can break out $10 or $15 million (my guess) and buy Ten's Complement, founded by Apple's former tech lead for ZFS, which is offering ZFS for the Mac today. The shipping Silver version is feature lite - but so is the price - and more fully featured versions are on the way.
Perhaps even before ReFS ships on W8.
Comments welcome, of course. I bought a copy of Ten's Complement Zevo Silver, but have yet to put it throught its paces. Sadly I don't have any investment in the company.