Re: PostgreSQL's handling of fsync() errors is unsafe and risks data loss at least on XFS

On Mon, Apr 09, 2018 at 03:02:11PM -0400, Robert Haas wrote:
> Another consequence of this behavior that initdb -S is never reliable,
> so pg_rewind's use of it doesn't actually fix the problem it was
> intended to solve.  It also means that initdb itself isn't crash-safe,
> since the data file changes are made by the backend but initdb itself
> is doing the fsyncs, and initdb has no way of knowing what files the
> backend is going to create and therefore can't -- even theoretically
> -- open them first.

And pg_basebackup.  And pg_dump.  And pg_dumpall.  Anything using initdb
-S or fsync_pgdata would enter in those waters.
--
Michael