The Samba-Bugzilla – Bug 13033
LDB open with LDB_FLG_RDONLY can cause the database to fail to open
Last modified: 2017-09-14 17:05:16 UTC
If an LDB is opened with LDB_FLG_RDONLY tdb will refuse to grant read locks.
Additionally, if LDB is opened with LDB_FLG_RDONLY a subsequent LDB will share the same tdb, which will be opened with O_RDONLY, and so fail to accept writes.