Subject: Re: wedges and what does that mean?
To: Martin Husemann <>
From: Johnny Billquist <>
List: current-users
Date: 09/04/2006 13:58:31
So, what are you saying?

Are wedges just partitions with another name, or is there really a 
The actual width of the size and offset is hardly a reason to say it's 
different. Is the information about wedges not stored on the disk? How 
do you find them in that case?

I'm probably dense, but this answer made it look no different from a 
partition, except the fact that they were 64-bit values. Which is nice, 
but it don't really make them any different.


Martin Husemann wrote:
> On Mon, Sep 04, 2006 at 01:02:16PM +0200, Bernd Ernesti wrote:
>>could someone please give me and others an overview what does it mean
> Let me try.
> Wedges are parts of a disk. They do not have partitions - for example
> on this machine I'm typing this on I have /dev/dk0 and /dev/dk1 -
> but there is no /dev/dk0a.
> They can be created by userland, via dkctl, or some other tools (for example
> mbrlabel could/should be enahnced to optionally created wedges from the
> parsed label).
> They also can be created by the kernel, for example to allow booting
> from a wedge. This is called autoconfiguration, and it is controlled
> via options DKWEDGE_METHOD_....
> But wedges have no inherent corelation to some on-disk partition format,
> like the disklabel which the old partition code used. Lots of magic/evil
> code will disapear from the kernel once the wedge conversion is complete.
>>I heard that it would be possible to use more then 2TB and that the old
>>disklabel way will go away.
> Yes. Wedges have 64 bit offset and size (both in blocks). One supported
> method to store information on disk is the EFI/GPT (Guid Partition Table)
> format, where you can store this big values (and have upto ~64k partitions
> per disk)
>>What does this mean to a machine which currently uses disklabel and how
>>are wedges configured?
> A machine can easily be converted by enabling the proper DKWEDGE_METHOD_*
> options to have the kernel autoconfigure the wedges needed for booting.
> Besides that, you need a few obvious changes to /etc/fstab - and that's
> it. No > 2TB partitions when using the old on-disk formats though.
> Martin