Quoting russell@coker.com.au (russell@coker.com.au):
Last time I checked XFS had no support for reducing the size of a filesystem.
Correct.
But if Stratis is going to use multiple XFS filesystems to compare with the multiple ZFS mount points or BTRFS subvols then it will be a massive problem.
The design paper claims online grow abilities adequately meets their needs. I've only just now skim-read that paper, so I cannot comment.
Stratis is aiming for a version 1.0 release next year, and version 3.0 is aimed at having ZFS feature parity. That's not good for all the people who need ZFS features today!
Welcome to the real world of software development, eh? RH aren't going to ship ZFS unless Oracle Corp. issue a licence exception (alongside the CDDL terms), and that's not going to happen. (Well, RH could ship FUSE_ZFS, but they aren't going to do that either, for reasons of performance.)
XFS has no support for checksums that compares to ZFS and BTRFS. To do it properly you need to do it in the filesystem.
Whitepaper section 10.2.2 et seq. talks about their plans in this area.