Subject: Re: disk caching
To: Chuck Swiger <firstname.lastname@example.org>
From: Dieter <email@example.com>
Date: 02/05/2006 12:59:53
> >>>> 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...)