Description of problem:
This might be tough to implement as RBD image metadata are part of different omap state files but we need to find a way to restrict creation of namespaces with RBD images which are already part of other GW groups as namespaces, as these volumes can be accessed by multiple clients causing data inconsistency. With huge scale, say 1K to 4K RBD images, it will be difficult for customer to keep track of used/unused images to create namespaces 
For now, it is decided to add an alert at 8.1. I raised https://bugzilla.redhat.com/show_bug.cgi?id=2359211 to implement actual resolution 

Version-Release number of selected component (if applicable):
ceph version 19.1.0-42.el9cp
cp.stg.icr.io/cp/ibm-ceph/nvmeof-rhel9:1.2.17-11


How reproducible: Always


Steps to Reproduce:
1. Deploy 4 nvmeof services with 4 GW groups having 2+ Gateways
2. Configure subsystems and add namespaces with a set of RBD images within a Gateway group
3. On other GW group, configure subsystems and add namespaces with same set of namespaces

Actual results: Same RBD images can be used to create namespaces in different GW groups


Expected results: Namespace addition should never succeed with RBD image already used by namespace in other GW group


Additional info: