Re: block device lock difference between netbsd-4 and netbsd-5

[Dima Veselov <i%kab00m.ru@localhost>]

On Sat, Jan 30, 2010 at 12:38:32PM +0100, Adam Hamsik wrote:
> 
> On Jan,Friday 29 2010, at 1:02 PM, Brad du Plessis wrote:
> 
> > I've noticed this difference between netbsd-4 and netbsd-5:
> > 
> > netbsd-4:
> > 
> > # dd if=/dev/wd0d of=/dev/null &
> > [1] 5330
> > # dd if=/dev/wd0d of=/dev/null &
> > [2] 6390
> > 
> > 
> > netbsd-5:
> > 
> > # dd if=/dev/wd0d of=/dev/null &
> > [1] 25717
> > # dd if=/dev/wd0d of=/dev/null &
> > [2] 26592
> > # dd: /dev/wd0d: Device busy
> > [2]    Exit 1                        dd if=/dev/wd0d of=/dev/null
> > 
> > Why the difference? Is there anything I can set (like in my kernel config 
> > file for 
> > example) to prevent the locking in netbsd-5?
> 
> You can't open block device more than once in netbsd > 5.0. If you need to do 
> it 
> something is wrong with your setup. You can still open raw devices more than 
> once.

Also, raw devices are much more faster in such reads or writes.

-- 
Sincerelly yours