UFS partitioning

Da Rock rock_on_the_web at comcen.com.au
Thu Dec 4 20:34:25 PST 2008

On Thu, 2008-12-04 at 10:49 -0500, Jerry McAllister wrote:
> On Thu, Dec 04, 2008 at 12:57:45PM +1000, Da Rock wrote:
> > 
> > On Wed, 2008-12-03 at 20:55 -0500, Robert Huff wrote:
> > > Da Rock writes:
> > > 
> > > >  Excuse my nose in here- I just have a couple of questions.
> > > >  
> > > >  1) It IS possible to boot from a dedicated disk?
> > > 
> > > 	Yes.  Can't remember the last time I used anything else.
> > 
> > So you've never booted from a disk that has been partitioned as a file
> > system?
> You are getting your terms scrambled here.
> Partitioning has nothing directly to do with creating a file system.
> You can build a filesystem (with newfs) on just about any piece
> of disk whether it is the whole disk, a slice of the disk or a partition
> of a slice.
> Making one of those divisions bootable is also pretty much an 
> independant operation too, though as far as I know, only whole
> disks and slices can be made bootable but not partitions - the
> fact that the partition contains the system files is not what
> makes it bootable.   Being bootable is dependant on the boot sector
> which gets the control from either the BIOS or an MBR and then finds
> the system partition (/), mounts it (Read Only) and finds system files 
> and starts those things running.

Yes, I would say I'm getting my terms mixed up- fortunately the actual
reality is clear in my head (hard as that is to believe..).

I have only one more question then: Why would you use "dangerously
dedicated mode" at all? I can only see where it might be useful for
files, no advantage to being a boot sector.

It was some time ago that I read up on all this, but what I remembered
was that BSD could use a dedicated disk- but only BSD could read and
write from it and this is dangerous. Maybe what I was reading was
regarding bootable and that was considered dangerous... At any rate I'm
very clear now.

Thanks for all the information guys- cheers

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