On Thu, Dec 28, 2000 at 12:25:13PM -0800, Bill Studenmund wrote:
> > however, the use of high minor numbers to represent normal disks is
> > a currently supported feature of the official NetBSD distribution,
> > and changing the interpretation of the minor number would break that.
> 
> Think about what this will do for minor numbers too. Assuming we only make
> room for 16 partitions (which strikes me as way too small - if we change,
> we should go to 64), partition i will have a radically different minor
> offsets on different ports. Some ports already support 16 partitions/disk,
> so this change will make wd0i minor 8 on some ports and minor 1048576 on
> others.
> 
> Ack! ls -l will make little sense!

given that device numbers are currently completely different on different
platforms, this isn't much of an issue right now.  but having a unified
device numbering system across all platforms would be a good goal as well.

64 partitions has the additional issue that the current on-disk
bsd disklabel format doesn't allow for that many entries,
so we would have to create yet another on-disk format to store
that many partitions.  the current bsd label layout is constrained
to one 512-byte sector on many platforms because of the placement of
the bsd label at sector 0 and the placement of the boot blocks
right after that.


> I think an LVM would be really cool, but that it solves a slightly
> different problem. All the LVM's I've seen get the whole disk, and divvy
> it up. That makes sharing disks between OSs hard. I think fixed
> partitioning will help us more with supporting multiple OSs on a disk.

an LVM will have to interoperate with existing partitioning schemes.
VxVM on solaris does interoperate with the solaris VTOC partitioning,
allowing you to map volumes to VTOC partitions.  this allows booting
from a partition/volume which is actually mirrored (once vxvm gets going).
VxVM on solaris also allows you to manage any VTOC partition as the
storage space for volumes.  usually you use the partition that maps
the entire disk, but you don't have to.

-Chuck