Subject: Re: 4K sector disks
To: Jason Thorpe <>
From: David Laight <>
List: tech-kern
Date: 03/24/2006 18:43:35
On Fri, Mar 24, 2006 at 09:30:03AM -0800, Jason Thorpe wrote:

Does anyone know what the mbr layout looks like for sectors != 512 bytes?
(with and without extended partitions).

I know there have been many patches to 'fix' fdisk, disklabel, newfs (etc)
for non-512 byte sectors, but I'm not sure if any of them DTRT with the
layout (I'm not even sure what TRT is).

For instance, do we put the netbsd disklabel 512 bytes from the start of
the disk? Or in the second sector?
In the latter case what happens to the bootstrap code that occupies
bytes 1024 onwards?

It would certainly be useful to be able to 'dd' a UFS filesystem between
disks with different sector sizes - provided the sector size is a
multiple of the fragment size.

I've even wondered if emulating large sectors would give us disklabel
support for disks > 2TB.


David Laight: