Re: Bypassing Directory Ownership Check in PostgreSQL 16.6 with Secure z/OS NFS (AT-TLS)

Thanks Tom and Laurenz for the explanation.
Let me try out a few things and get back to you if needed.

Thanks,
Amol

On Mon, Jul 14, 2025 at 7:37 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:

> Laurenz Albe <laurenz.albe@cybertec.at> writes:
> > It is not a good idea to have a mount point be the data directory.
>
> ^^^ This. ^^^
>
> That is primarily for safety reasons: if for some reason the
> filesystem gets dismounted, or hasn't come on-line yet during
> a reboot, you do not want Postgres to be able to write on the
> underlying mount-point directory.  There is a sobering tale
> in this old thread:
>
> https://www.postgresql.org/message-id/flat/41BFAB7C.5040108%40joeconway.com
>
> Now it didn't help any that they were using a start script that
> would automatically run initdb if it didn't see a data directory
> where expected.  But even without that, you are in for a world of
> hurt if the mount drops while the server is running and the server
> has any ability to write on the underlying storage; it will think
> whatever it was able to write is safely down on disk.  To prevent
> that, the server must not have write permissions on the mount
> point, which dictates making a separate data directory (with
> different ownership/permissions) just below the mount.
>
> Do not bypass that ownership/permissions check.  It is there
> for very good reasons.
>
>                         regards, tom lane
>


-- 
-regards
Amol