Subject: Re: MAXPARTITITONS > 8 (was: Re: mbrlabel fixes)
To: Reinoud Zandijk <>
From: Richard Rauch <>
List: current-users
Date: 12/28/2000 23:06:58
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?

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.  (^&)

If this would work, it would let you access more or less as many
filesystems as you like, without modifying any of our actual disk
structure in any way---and with no (as far as I know) hard limits anywhere
in sight.  (Although I concede that the idea of a bunch of pseudo-disks
isn't the most elegant solution...)

(Or can you already do this by configuring 1 or more vnodes to use the raw
partition /dev special file for a disk?)

Well, it's just an idea from Kansas.  What can I say?

  "I probably don't know what I'm talking about."