Is the fsync() fake on FreeBSD6.1?

[Leo Huang]

hi, Arne,

> You could do this test:
> 1. write some data with dd if=/dev/zero of=/tmp/a bs=1m count=100
> 2. then fsync /tmp/a
> 3. then listen to the hard disc
> 4. repeat it until u r sure, if the hard disc reacts on the fsync command...
> :-)
Good idea. But the room is noisy. I think I can not hear.  :-(


> I do not know, if it is possible to turn off the write cache of a SCSI disc...
How can I hnow whether the write cache is turned off?

2006/6/27, R. B. Riddick <arne_woerner at yahoo.com>:
> On Tuesday, 27 June 2006 at 10:18:47 +0800, leo huang wrote:me
> > And how I can confirm this?
> >
> You could do this test:
> 1. write some data with dd if=/dev/zero of=/tmp/a bs=1m count=100
> 2. then fsync /tmp/a
> 3. then listen to the hard disc
> 4. repeat it until u r sure, if the hard disc reacts on the fsync command...
> :-)
>
> I do not know, if it is possible to turn off the write cache of a SCSI disc...
>
> On the freebsd-geom@ list was something about a new feature (the BIO_FLUSH
> request), that can flush the write caches of hard discs. But it just works for
> ata and amr discs currently... See:
> http://docs.freebsd.org/cgi/getmsg.cgi?fetch=3624+0+archive/2006/freebsd-geom/20060625.freebsd-geom
>
> -Arne
>
>
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