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

Hi Robert,

On Tue, Apr 10, 2018 at 11:15:46AM -0400, Robert Haas wrote:
> On Mon, Apr 9, 2018 at 3:13 PM, Andres Freund <andres(at)anarazel(dot)de> wrote:
> > Let's lower the pitchforks a bit here. Obviously a grand rewrite is
> > absurd, as is some of the proposed ways this is all supposed to
> > work. But I think the case we're discussing is much closer to a near
> > irresolvable corner case than anything else.
>
> Well, I admit that I wasn't entirely serious about that email, but I
> wasn't entirely not-serious either. If you can't find reliably find
> out whether the contents of the file on disk are the same as the
> contents that the kernel is giving you when you call read(), then you
> are going to have a heck of a time building a reliable system. If the
> kernel developers are determined to insist on these semantics (and,
> admittedly, I don't know whether that's the case - I've only read
> Anthony's remarks), then I don't really see what we can do except give
> up on buffered I/O (or on Linux).

I think it would be interesting to get in touch with some of the
respective linux kernel maintainers and open up this topic for
more detailed discussions. LSF/MM'18 is upcoming and it would
have been the perfect opportunity but it's past the CFP deadline.
It may still worth contacting the organizers to bring forward
the issue, and see if there is a chance to have someone from
Pg invited for further discussions.

Best regards,
Anthony