Subject: Re: newfs can't make filesystems over 1TB in size
To: Brian Buhrow <>
From: Luke Mewburn <>
List: current-users
Date: 12/08/2002 11:22:15
On Sat, Dec 07, 2002 at 11:01:46AM -0800, Brian Buhrow wrote:
  | 	Hello Luke.  I think I also pointed out that the FreeBSD folks seem to
  | define ffsize as a quad_t, a signed 64-bit value.  How hard would it be to
  | convert NetBSD to use this as the underlying access method?  This seems
  | like it would buy us some time in terms of what size filesystems we could
  | support without having to change the underlying size of the sector.

A significant chunk of the existing file system code in the kernel
uses daddr_t (or derived types, such as ufs_daddr_t, which is defined
to be int32_t for on-disk purposes, in case daddr_t changes size)
to refer to underlying disk sectors.

I'm not sure of the exact effort involved in changing this; maybe
someone with more experience in the underlying file system structure
(for example, Bill Studenmund or Chuck Silvers...) can comment here.

  | -Brian
  | On Dec 8,  6:50am, Luke Mewburn wrote:
  | } The kernel uses daddr_t to access underlying disk sectors.
  | } daddr_t == int32_t == 2^31.
  | } With 512 byte (2^9) sectors, 2^9 x 2^31 == 2^40 == 1TB.
  | } 
  | } If I recall correctly, we don't cleanly support larger sectors yet.
  | } 
  | } Luke.
  | >-- End of excerpt from Luke Mewburn