FreeBSD vinum volume manager
Gvinum was an implementation of the vinum volume manager in GEOM.
It underwent many changes since the initial import in 5.0. This page explained some basics about gvinum as well as point out its short-comings, and how they are addressed.
However, as of early 20201, gvinum has been deprecated. At this time it is seen as mostly unmaintained, and inferior to ZFS for most purposes.
Support for using gjournal on top of gvinum volume
The problem is in PR http://www.freebsd.org/cgi/query-pr.cgi?pr=133604
The problem is also in HEAD, and will probably be fixed only there unless it turns out to be easily fixable in 7.x as well.