Re: 9.6 and fsync=off

Andres Freund <andres@anarazel.de> writes:
> On 2016-05-02 10:07:50 -0400, Robert Haas wrote:
>> - If that flag is set on a subsequent startup, say:
>> WARNING: Recovery was previously performed with fsync=off; this
>> cluster may be irretrievably corrupted.

> Well, the problem with that is that postgres crashes are actually
> harmless with regard to fsync=on/off. It's just OS crashes that are a
> problem. So it seems quite likely that the false-positive rate here
> would be high enough, to make people ignore it.

That's a pretty good point.  Also, as sketched, I believe this would
start bleating after a crash recovery performed because a backend
died --- which is a case where we know for certain there was no OS
crash.  So this idea needs some more thought.
        regards, tom lane