Ceph

Construction step:

first:
create 2 Mons and 2 Mgrs in the Ceph cluster.

second:
I can get "ceph pg dump" info;
and use ceph-kvstore-tool can get "mgr_command_descs" table info,as fllows:

          ......
          mgr     9
          mgr     ever_had_active_mgr
          mgr     first_committed
          mgr     last_committed
          mgr_command_descs
          mgr_metadata    192.7.7.141
          mgr_metadata    192.7.7.142
          mgrstat 50599
          ......
         

third:
join the new Mon, and use "ceph pg dump" command in the new Mon,
I can get fllow err info:

         *Error ENOTSUP: this command is obsolete* 
         

In addition,use ceph-kvstore-tool can not get "mgr_command_descs" table info
(This will lead to new Mon load the mgr commands is Fail, you can get "Failed to load mgr commands:" info in the Mon log),
as fllows:

         ......
         mgr     9
         mgr     ever_had_active_mgr
         mgr     first_committed
         mgr     last_committed
         mgr_metadata    192.7.7.142
         mgrstat 10261
         ......