Using a hard drive without partitions

Glenn Dawson glenn at
Sun Jul 31 02:12:36 GMT 2005

At 10:58 AM 7/30/2005, Nikolas Britton wrote:
>On 7/30/05, Gary W. Swearingen <garys at> wrote:
> > Nikolas Britton <nikolas.britton at> writes:
> >
> > > Drive:
> > >   Dangerously dedicated
> > >   /dev/da0s1
> > >   newfs -O2 -U
> >
> > I think you're using "dangerously dedicated" wrongly. A DD disk is one
> > which has no standard partition table in the MBR; the "disklabel"
> > sectors (16) start at sector 0 (or with your no-secondary-partitions-
> > either method, your filesystem would start there (newfs /dev/da0)).
> >
>But in FreeBSD your disk needs a slice otherwise it's not compatable
>with fdisk / bsdlabel / growfs... I think.

bsdlabel will happily label a disk with no slices and give you /dev/ad0a etc.

> > You've got a standard partition table with the s1 entry in use, which
> > is not "dangerous".  The FAQ has an entry on DD disks.
>But it is "dangerous" because it starts at sector 0. I've read that
>FAQ as well as greg's book, Lucas's book, unix power tools, the man
>pages, handbook, etc. I will reread them again.

The only danger in not having the slice table is that if you use non BSD 
tools, such as the ones that come with windows, they will potentially write 
over things that that you don't want them to.  Also, without the slice 
table on your boot disk, the BIOS wont know what to do since it looks for 
the active slice and attempts to boot it.

Another reason to have the slice table is if you want to share use of the 
disk with other operating systems, such as linux or windows or whatever.


> >
> > I can't say much about your main question; I've never heard of doing
> > it.  It sounds less "dangerous" than putting a FS in a file, like
> > we do with ISO filesystems all the time.
> >
>Yea that's the problem ;-)..... I've never heard of doing it like that
>too but it does work.
>I'm going to be working on this server today and I'll post some of the
>details of fdisk, bsdlabel, etc. to see if I can help clarify things.
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