How to sync a file on FreeBSD? [SOLVED]

[Michael Sierchio]

On Fri, Jul 22, 2011 at 7:42 AM, Polytropon <freebsd at edvax.de> wrote:

> But wouldn't sync() (see "man 2 sync") make sure that
> all buffers, even in regards to soft updates, get
> immediately flushed / written?

Apparently not. I think most of Matt Dillon's notes are still relevant.

http://leaf.dragonflybsd.org/mailarchive/kernel/2010-01/msg00005.html

>> In order to
>> implement a stable queue, it would be best to use a different
>> filesystem.
>
> What type of filesystem would match those requirements?

I would make a UFS filesystem without Softupdates enabled,  use
fflush() and wait for a proper ack before promising to the caller that
the bits will survive something like pulling the plug.  Softupdates
guarantees metadata consistency. I would probably make decisions about
block and fragment sizes based on knowledge of the physical device's
buffer mechanism, sector sizes, etc.