New device drivers don't see beyond 15 partitions in fc7

[Gilboa Davara]

On Fri, 2006-12-22 at 08:32 +0100, Hans de Goede wrote:
> Gilboa Davara wrote:
> > On Thu, 2006-12-21 at 17:57 -0500, Clyde E. Kunkel wrote:
> >> Hello,
> >>
> >> With the change from traditional /dev/hd* type device nodes to /dev/sd* 
> >> type nodes, I see that the highest partition number that can be used is 
> >> 15.  Will this change so that higher numbers will be available?  I do 
> >> have a system that has a drive with almost 30 small partitions used in a 
> >> research effort and the number of partitions has not been an issue thru fc6.
> >>
> >> -- 
> > 
> > Use LVM.
> > Trust me.
> > You won't be sorry.
> > 
> 
> Use lvm is not the answer, if this was possible before the system should 
> upgrade to FC-7 flawlessly, if /dev/hdx accomodated more then 15 
> partitions, then so should the new /dev/sdx when it becomes the new 
> device for this disk.
> 
> Regards,
> 
> Hans
> 

Short answer: Use LVM!
Long answer: Asking the kernel hackers to risk breaking compatibility
inside inside the SCSI layer [1] and break
God-knows-how-many-different-user-land-applications just to handle a
0.001% end case that can be handled differently (disable libata, use
LVM), is pure madness.
You can argue the it should be possible to disable libata in special
end-cases such as the OP's case (and I'll second your motion), but
that's another matter altogether.

- Gilboa
[1] I'm not very familiar with the partition/fs code, but something
tells me the 16x minor->physical ID translation is hard coded
everywhere. Plus, increasing the number of partitions to 63 will reduce
the number of possible SCSI drives to 8 (?? I'm not sure. should be
512/64) and there are many people (including myself) that have more then
8 SCSI/SATA drives configurations running software RAID5/6.