Re: Online verification of checksums

On Sun, Mar 03, 2019 at 03:12:51AM +0100, Tomas Vondra wrote:
> You and Andres may be right that trying to verify checksums online
> without close interaction with the server is ultimately futile (or at
> least overly complex). But I'm not sure those issues (torn pages and
> partial reads) are very good arguments, considering basebackup has to
> deal with them too. Not sure.

FWIW, I don't think that the backend is right in its way of checking
checksums the way it does currently either with warnings and a limited
set of failures generated. I raised concerns about that unfortunately
after 11 has been GA'ed, which was too late, so this time, for this
patch, I prefer raising them before the fact and I'd rather not spread
this kind of methodology around the core code more and more. I work a
lot with virtualization, and I have seen ESX hanging around I/O
requests from time to time depending on the environment used (which is
actually wrong, anyway, but a lot of tests happen on a daily basis on
the stuff I work on). What's presented on this thread is *never*
going to be 100% safe, and would generate false positives which can be
confusing for the user. This is not a good sign.
--
Michael