Alfred Perlstein wrote:
>
> * Andre Oppermann <[EMAIL PROTECTED]> [010206 12:30] wrote:
> > Rik van Riel wrote:
> > >
> > > On Tue, 6 Feb 2001, Andre Oppermann wrote:
> > >
> > > > But please answer me one question: Is the link() call atomically
> > > > in FFS/UFS w or w/o softupdates? Meaning when the call returns
> > > > the meta- data is written to stable storage like with fsync()?
> > >
> > > Since when does `atomic' equal `synchronous' ?
> >
> > Because otherwise it would not be atomically, would it?
>
> Softupdates does it atomically but not synchronously. :)
>
> Basically, the in-memory view of the filesystem != the on-disk
> version.
>
> The update happens atomically with respect to locking in memory,
> so running processes never see a non-atomic snapshot of the directory,
> but if a crash occurs the disk may be several steps behind the
> memory at the time of the crash.
Maybe this explains why DJB recommends against the usage of
softupdates...
But anyway since qmail does fsync() frequently (which is honored by
softupdates) then simply the roll-back/forward would kick in. So
following this it should be no problem.
Maybe DJB recommends against it because softupdates wasn't perfectly
mature until recently (and he uses OpenBSD for his developement which
AFAIK lags behind FreeBSD in this respect).
--
Andre
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