Thanks a lot for this feed back!
I've never had any practical experience with Ceph, MooseFS, BeeGFS or Lustre:
GlusterFS to me mostly had the charme of running on 1/2/3 nodes and then anything beyond
at a balanced benefits in terms of resilience vs. performance... in theory, of course.
And on top, the fact that (without sharding), if hell broke loose, you'd always have
access to the files on the file system below, was a great help in building up enough
confidence to go and try it.
Politics and real-world came much later and from my experience with TSO, 370s, Lotus Notes
and QuickTransit, I can appreciate the destructive power of IBM: Let's just hope they
don't give into the temptation of "streamlining their offerings" the wrong
direction.