You're probably correct (I'll test it tonight). I misread 'cylinder' as
'sector' in the ccd(4) manpage:

  Note that the `raw' partitions of the disks should not be combined. 
  Each component partition should be offset at least one cylinder from the
  beginning of the component disk.  This avoids potential conflicts
  between the component disk's disklabel and the ccd's disklabel.  The
  kernel will only allow component partitions of type FS_BSDFFS.


On Wed, 9 Dec 1998, Manuel Bouyer wrote:

> On Dec 8, Scott Bartram wrote
> > 
> > [...]
> > 8 partitions:
> > #        size   offset    fstype   [fsize bsize   cpg]
> >   a:  8890759        1      4.2BSD     1024  8192    16   # (Cyl.    0*- 5927*)
> 
> This '1' offset looks suspicious to me. I think your 'a' partition is still
> in the disklabel area, and this the first sectors are read only.
> Try something higther, like '32'.
> 
> --
> Manuel Bouyer, LIP6, Universite Paris VI.           Manuel.Bouyer@lip6.fr
> --
>