Does FreeBSD start slices at head boundaries?

Polytropon freebsd at
Fri Jul 6 18:26:01 UTC 2012

On Fri, 06 Jul 2012 19:47:27 +0200, Bas Smeelen wrote:
> On 07/06/2012 07:28 PM, Robert Huff wrote:
> > Ryan Coleman writes:
> >
> >>   > Anyway just don't make slices at all if your disk is dedicated
> >>   > to FreeBSD
> >>   
> >>   Except for swap, right?
> > 	Why do you say that?
> >
> >
> > 				Robert huff
> >
> >
> >
> I think Ryan means partition and not slice?
> I would not recommend no slices at all, It's deprecated to use 
> "dangerously dedicated disks"

First of all, it's "dedicated disks", there's nothing dangerous
related. :-)

If you are using the MBR approach ("old way"), you can do
either creating a "DOS primary partition", a slice, which
then will contain your partitions: a swap partition and
one or more UFS partitions. So you have ad0s1a, ad0s1b
and so on.

When you omit the slice and create the partitions on the "bare
disk", you have a dedicated layout. FreeBSD will run with
it without any problem. It _may_ be possible that some
systems like "Windows" have trouble with this approach,
but if you're going to use FreeBSD only on that disk, there
is no danger, no problem. You have ad0a, ad0b and so on.

If you are using the GPT approach ("new way"), you create
partitions using a different tool set, setting them to be
a file system or a swap partition. You end up in ad0p1,
ad0p2 and so on. Note that those aren't "DOS primary
partitions" anymore, outdated systems may not properly
recognize them.

If you label your partitions (you can do that with both
approaches), you don't need to deal with device names at

> Starting with 9 I don't see slices in mount ouput anymore but still 
> there are FreeBSD partitions in slices (which is a partitions in dos terms)
> Example / is now disk0p1 it used to be disk0s1a

Correct, this relation can be constructed.

To OP:

If you omit the slice and just create two partitions (one for
FS and one for swap), FreeBSD will use this fine. Just make
sure to set the boot parameters properly. Or simply use the
GPT-related tools, so you don't have to deal with the question
at all.

Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...

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