> >>>> This makes predictable and reliable crash recovery of on-disk data structures
> >>>> (filesystems, databases etc.) impossible.
> >>> I was under the impression that filesystems had the ability to force
> >>> the order of writes when they needed to?  Am I misremembering?
> >> The filesystem can attempt to enforce write order.
> > 
> > The quote from FreeBSD makes it sound like the filesystem cannot
> > enforce write order, unless one gets rid of block devices.
> > This just doesn't sound right.
> 
> Which quote are you talking about?

The one just above, that goes "This makes predictable and reliable crash
recovery of on-disk data structures (filesystems, databases etc.) impossible."

Another quote from the FreeBSD page:

	"The caching will reorder the sequence of write operations"

It has been a long time since I studied this, but I seem to recall that
there were ways to force the sequence of write operations.  Perhaps I
am misremembering?  Perhaps the new-fangled unified buffer cache broke
this?  (Yet another thing I need to read up on...)