clear metadata using dd?

[Pawel Jakub Dawidek]

On Fri, Jan 26, 2007 at 03:12:46PM -0600, Rick C. Petty wrote:
> On Fri, Jan 26, 2007 at 08:54:30PM +0100, Pawel Jakub Dawidek wrote:
> > On Fri, Jan 26, 2007 at 01:14:14PM -0600, Rick C. Petty wrote:
> > > On Fri, Jan 26, 2007 at 05:57:23AM -0800, R. B. Riddick wrote:
> > > However, I'm not a big fan of the priority placed on the I/O to sync the
> > > disks.  Pretty much during a resync, the box is unusable for file/disk I/O
> > > for a number of hours.  Apps using GNOME/GTK are almost non-responsive, and
> > > forget about even using java/eclipse.  I haven't found a good way to tune
> > > gmirror's sync. [...]
> > 
> > Have you tried setting kern.geom.mirror.sync_requests to 1?
> 
> I've fiddled with all of kern.geom.mirror.* knobs.  I have no idea what
> these knobs do (although I've made educated guesses), and the man page is
> quite lacking.

Maybe we should also introduce some delay between sync operation when
there are other requests in the queue...

> > > [...] I also wish you could pause the sync, restart, and unpause
> > > it where it left off. [...]
> > 
> > It should just work. When you reboot during the sync process it should
> > continue after the reboot from the place it stopped.
> 
> I have *never* seen this behavior, and I have restarted mid-sync a number
> of times.  After each time, "gmirror status" reports 0% complete.  I've
> tried this on 5.4, 5.5, 6.0, 6.1, but not 6.2 yet.

Works just fine here:

	# gmirror label foo ad4d
	# gmirror insert foo ad6d
	<wait a bit>
	# gmirror status
	Name    Status  Components
	mirror/foo  DEGRADED  ad4d
	                      ad6d (10%)
	# reboot
	# gmirror load
	# gmirror status
	Name    Status  Components
	mirror/foo  DEGRADED  ad4d
	                      ad6d (11%)

-- 
Pawel Jakub Dawidek                       http://www.wheel.pl
pjd at FreeBSD.org                           http://www.FreeBSD.org
FreeBSD committer                         Am I Evil? Yes, I Am!
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