Re: backup tools ought to ensure created backups are durable

On 2016-03-29 10:06:20 +0200, Magnus Hagander wrote:
> On Tue, Mar 29, 2016 at 8:46 AM, Jim Nasby <Jim.Nasby@bluetreble.com> wrote:
> 
> > On 3/28/16 11:03 AM, Magnus Hagander wrote:
> >
> >>
> >> That should work yeah. And given that we already use that check in other
> >> places, it seems it should be perfectly safe. And as long as we only do
> >> a WARNING and not abort if the fsync fails, we should be OK if people
> >> intentionally store their backups on an fs that doesn't speak fsync (if
> >> that exists), in which case I don't really think we even need a switch
> >> to turn it off.
> >>
> >
> > I'd even go so far as spitting out a warning any time we can't fsync
> > (maybe that's what you're suggesting?)
> 
> 
> That is pretty much what I was suggesting, yes.
> 
> Though we might want to consolidate them in for example pg_basebackup -Fp
> and pg_dump -Fd into something like "failed to fsync <n> files".

I'd just not output anything if ENOTSUPP or similar is returned, and not
bother with something as complex as collecting errors.