See https://bugzilla.redhat.com/show_bug.cgi?id=1491771 RHEV-M supports creating a storage domain with a single Gluster brick. Admin Guide, Using Red Hat Gluster Storage as a Storage Domain, needs to be updated.
This is for RHHI clusters, this ability has existed for a long time in RHSC.
In response to comment 1, moving to one of the RHHI doc components to allow the team to review.
Avital, sorry for the long wait on this one. As far as I can see there's nothing in the RHV Admin Guide (assuming you meant the RHV guide) to say that this wouldn't be supported, so I can't see a need to add a statement calling this out specifically. Can you elaborate in case I have this wrong?