dangerously dedicated disks and 8-stable status

[Jerry McAllister]

On Fri, May 07, 2010 at 10:06:31PM +0100, krad wrote:

> On 7 May 2010 16:17, A. Wright <andrew at qemg.org> wrote:
> 
> >
> > On Fri, 7 May 2010, krad wrote:
> >
> >  FYI happened on 2nd box as well but I least it didnt catch me out this
> >> time
> >> 8). It seems that pre freebsd-8 it is permissible to use format
> >> <dev>s1[a-h]  , however in freebsd-8+ to you are forced to use the  format
> >> <dev>[a-h].
> >>
> >
> > I have noted peculiarities also in this move (as noted above:
> > 8.0-RELEASE upgrade -- no files visible), but different ones
> > from what you are seeing.
> >
> > I have begun to suspect that part of the issue is that my
> > drives at one time were set up in "dangerously dedicated"
> > mode, but later changed to "slice-based" mode.  It may be
> > that there are still sectors near the beginning of the disk
> > with old information in them.
> >
> > Currently I have one disk remaining from the old setup, for
> > which I only get /dev entries produced for the device, and
> > for partition 'a' (ie, /dev/ad10, /dev/ad10a), however if
> > accessed from 7.2, I can see and mount /dev/ad10s1[a,d-g].
> >
> > Might your disks have similar "old" information in the first
> > track (but not in the first sector), or do you refer to a
> > new disk, or one to which a number of sectors of zeros was
> > written?
> >
> > Thanks for the info,
> > A.
> >
> >
> > Both were a 6.2 box upgraded to 7-stable then 8. I didnt build the initial
> os's so have no idea what the state of the disks were unfortunately. I have
> about 20 more or so upgrades to do in the next few weeks so expect the trend
> to continue as they were all built around the same time by the same person

If you are worried that there might be something in an early sector 
on the disk, you can get rid of it by using dd(1).  
If your drive is /dev/ad10, then do the following.

  dd if=/dev/zero of=/dev/ad10 bs=512 count=1024

Actually any count over 32 should work, but it takes no time
so use a biger one.

This will work before slicing and partitioning the drive or will
wipe out previous slicing and partitioning.

////jerry     

  
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