clear metadata using dd?

[Pawel Jakub Dawidek]

On Tue, Jan 09, 2007 at 04:16:43PM -0300, Fernan Aguero wrote:
> On 1/9/07, Pawel Jakub Dawidek <pjd at freebsd.org> wrote:
> >On Tue, Jan 09, 2007 at 10:24:04AM -0300, Fernan Aguero wrote:
> >> On 1/9/07, Pawel Jakub Dawidek <pjd at freebsd.org> wrote:
> >> >On Mon, Jan 08, 2007 at 11:13:15PM -0300, Fernan Aguero wrote:
> >> >> On 1/8/07, Gary Palmer <gpalmer at freebsd.org> wrote:
> >> >> >On Mon, Jan 08, 2007 at 07:45:06PM -0300, Fernan Aguero wrote:
> >> >>
> >> >> [snipped]
> >> >>
> >> >> >> gama# gstripe label -v gs0 /dev/ad4s3 /dev/ad6s3
> >> >> >> Can't store metadata on /dev/ad4s3: Operation not permitted.
> >> >> >>
> >> >> >> This might be because ad4s3 had been part of a gmirror device before I
> >> >> >> reorganized my disks and moved the mirror to the s2 slice.
> >> >>
> >> >> [snipped]
> >> >>
> >> >> >Any reason that "gstripe clear" or "gmirror clear" doesn't work?  Thats what
> >> >> >they're meant to do, as far as I know.
> >> >>
> >> >> because ad4s3 is no longer part of gm0?
> >> >
> >> >You get "Operation not permitted." because someone already keep ad4s3
> >> >open for writing. Could you send output of 'sysctl -b kern.geom.confxml'
> >> >so we can find out who?
> >>
> >> http://omega.iib.unsam.edu.ar/kern.geom.confxml
> >[...]
> >
> >In this output size of ad4 is 160041885696 bytes.
> >
> >In your first post, slices are configured this way:
> >
> >gama# fdisk -s /dev/ad4
> >/dev/ad4: 310101 cyl 16 hd 63 sec
> >Part        Start        Size Type Flags
> >   1:          63    16771041 0xa5 0x00
> >   2:    16771923   146795229 0xa5 0x80
> >   3:   146795292   188742708 0xa5 0x00
> >
> >If ad4s3 starts at 146795292 sectors and is 188742708 sectors big, which
> >bascially means, that ad4s3 end at offset:
> >
> >        (146795292+188742708)*512 = 171795456000 bytes
> >
> >160041885696 < 171795456000, which means your slices are misconfigured.
> >Correct that and it should work.
> 
> OK, so perhaps the problem is that I used 160Gb in my calculations
> for the media size, expecting that fdisk will 'round down' the size of
> the last slice to match available space.
> 
> I recalculated all the start/length values for my slices and changed
> the fdisk.config I used with fdisk -f and now everything is fine.
> 
> Thanks!
> 
> <thinking to myself>
> but why was I ever allowed to go farther from the end of the media size?
> why didn't fdisk say anything?
> why didn't geom -- now I know that every single storage provider
> is managed by geom :) -- say anything?
> 
> Wouldn't it be good if one could tell fdisk to create a slice to start at a
> given sector and use '*' as the length (much as bsdlabel allows) so that the
> slice would occupy all remaining space?, like in
> p 3 165 146800795 *
> </thinking to myself>

fdisk(8) isn't too user friendly, that's for sure. Marcel Moolenaar is
doing some work in this area, so he can come up with something better in
the future.

-- 
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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