Re: write alignment matters?

[Michael van Elst <mlelstv%serpens.de@localhost>]

On Fri, Jun 24, 2011 at 12:02:05PM -0400, Thor Lancelot Simon wrote:
> On Fri, Jun 24, 2011 at 07:50:35AM +0000, Michael van Elst wrote:
> > 
> > Similar to raw devices in performance, I/O caching, and without the
> > hardware constraints regarding block sizes or alignment. I.e. something
> > that lets you treat disk contents like a regular file.
> 
> At least for NetBSD, that's never been true.  The most glaring problem
> is that there's no protection against causing the same underlying disk
> blocks to be multiply cached by accessing the buffer cache with a different
> stride.

Well, the code assumes that disklabel (used by the block device)
and filesystem agree on block size. But there are probably even
bugs with that and without disklabel there is somewhere a 2kB
default.

-- 
                                Michael van Elst
Internet: mlelstv%serpens.de@localhost
                                "A potential Snark may lurk in every tree."