On Fri, Dec 20, 2002 at 12:51:33PM +1100, Daniel Carosone wrote:
> For now, lets just assume LVM's do private and magical things inside
> its components to make mirrored/striped/raid5/etc chunks into a
> sequential logical block device, and that we don't want to speculate
> how just yet.

That will also, almost certainly, include private metadata in the
components (in case that wasn't clear).

> regular useful labelling things as marking filesystem type, read-only
> flags, sizes, etc.  Seems helpful. 

Read-only flags for partitions is something Solaris has, that any
new partitioning format for NetBSD (in core or on disk) should
grow. Handy, especially if the partitions are shared with other
OS's.

To elaborate on what an LVM might need from diskparts, on order to
publish the LV's:

 - a way to say that the partitions are logical, so only the size
   and not the offset is meaningful.  Just using 0 for all starts
   might confuse a tool that wants to make sure your partitions
   don't overlap.

 - a way to bind the actual device for the lv into the diskpart.
   I see this happening by the LVM arranging the LV to have the
   matching minor number for the diskpart entry it publishes it as.

 - a way to learn about changes made by other tools (like the one
   that changes the readonly flag) so that it can store an propagate
   this information in its private metadata across reboots.

--
Dan.