On Mon, 2025-07-14 at 14:30 -0400, Tom Lane wrote: > (I have a vague idea that there are system-level security hazards, > not specific to Postgres, if mount-point directories are publicly > writable. Don't feel like researching that though.)
Well, if you are using an ext? file system, there is a lost+found directory where fsck places links to orphaned inodes. If the PostgreSQL user owns the mount point and wants to use "initdb" to create a data directory in it, the program will fail and complain that the directory is not empty. The danger is great that the user removes the lost+found directory to solve the problem. True, one could re-create it with "mklost+found", but if a DBA is uneducated enough to remove the directory in the first place, the risk is high that he wouldn't think of creating it again, which is a problem if the file system ever becomes corrupted. All this doesn't apply to NFS, but it is yet another reason (apart from the safety of a subdirectory that doesn't exist on the file system underlying the mount point) why we should continue to recommend that the data directory be not a mount point. Yours, Laurenz Albe
