Today I decided to format a spare 1 TB electromechanical drive that I just use for file backups with the ReFS file system. I figure through experimentation with non-critical data I can get to know the implementation.
Lo and behold Windows 8.1 won't let you select ReFS at the normal Format prompt in DiskMgmt.msc, but there is a way to do it through the recovery console. I managed it...
For those of you unfamiliar with it, there's more on ReFS here:
Anyway, I copied about 850 GB of data to the drive (XCOPY)(, then read it back without error in comparison.
ReFS seems to have a general tendency to prioritize writes over reads, so while I was copying data to it, the comparison program read back the data fairly slowly. It was about 8 MB/sec read speed while maintaining 80 MB/sec writes. There was a significant lack of "frantic seeking". I could barely hear the drive at all.
But once the writes completed the reads cooked with gas - as fast as I've seen this drive go: 120 MB/sec.
I suspect the case of copying literally hundreds of gigabytes from a faster source while simultaneously trying to read is probably not common, and that it will work well in normal operation. I'll certainly be continuing to experiment with it.
Here are some interesting screen grabs (hope these come through okay):
The RAM cache seems to work particularly well with this file system. Note this uncached vs. cached performance difference with a benchmark that simulates multiple processes reading and writing...