@Tex1954 interesting finding re speed. Expecially since btrfs does lot more than almost all other filesystems with regard to check summing. Likely there is something else going on here.
Yes, Rockstor had issues a while ago with hanging onto old pools in all drives removed scenarios. And since 3.9.2-57 (from your screen pic) we have made some major improvements in this area. See:
from 14 months ago. 3.9.2-57 was release in April 2020 (16 month ago):
Release 3.9.2-57 · rockstor/rockstor-core · GitHub 16 months ago.
The recommended version for new deployment / performance testing is now 4.0.8-0 from a couple of days ago (I’ve not yet updated the downloads page which still states 4.0.7):
V4 Stable Release Candidate 9
Plus it’s btrfs kernel and userland is fully updated. But our 3.9.2-57 had older btrfs even on release. It’s one of the main reasons we embarked on this OS move from CentOS to openSUSE.
See how you get on with that one. We have also, in this latest version, worked around the known upstream docker/Rock-ons IPv6 issue we have had of late by re-enabling (but still not managing) IPv6.
Hope that helps.