Subject: Re: MAXPARTITITONS > 8 (was: Re: mbrlabel fixes)
To: Richard Rauch <>
From: Johan Ihren <>
List: current-users
Date: 12/31/2000 16:54:11
Richard Rauch <> writes:

> It's hard to say how many partitions one might actually want.  The primary
> motivation for more here seems to be for handling shared access between
> multiple operating systems.  How many operating systems might one install
> on a single disk?

I fully agree that the number of needed partitions seem to be more
dependent upon the need to access filesystems belonging to other OSes
than a need to micromanage storage local to NetBSD. This is exactly
why I think an easy way out where we go from 8 to 16 or thereabouts is

I hope I will never fragment my NetBSD storage into more than, let's
say 8 pieces (/, /var, /usr, /usr/src, /usr/{local,pkg}, /usr/home and
two more) on one disk. Likewise, I sincerely hope I will never have to
run more than the present 3 OSes on my laptop. And if there only was a
VMware for NetBSD I'd be much closer to finally ditching Lunix... ;-)

> At the same time, you don't really need all of those partitions to start
> booting any single OS.  One is enough to start it; 2 is probably as many
> as you'll actually need to get all normal services up.

>, what if additional partitions were accessed by something like a
> vnode?  (Or what if regular vnodes were extended to let you also mark raw
> sections of disk?)  Then you could create additional disklabelable
> pseudo-disks from chunks of real disk.  I'm not sure how many vnodes we
> get (or whether they are dynamically allocated), but at worst, you'd have
> to compile a new kernel to get more vnodes.

> (If not vnodes per se, then vnode-like objects.  If making vnodes support
> both files and raw partitions is too much, then call the new objects
> ``unodes'' in keeping with UVM and UBC.  (^&)

I cannot comment on whether this is technically feasible, but I
certainly agree that the need for "partitions" for foreign filesystems
belonging to other OSes is for exchanging data, not to boot from. So,
if access to those filesystems can be arranged in a non-partition-
consuming way that's ok too.


Johan Ihrén
Autonomica AB