On Fri, Dec 4, 2009 at 12:33 PM, Jonathan Thornburg <jth...@astro.indiana.edu> wrote: > Christopher Zimmermann <madroach () zakweb ! de> asked >> is it possible to install two OpenBSDs on the same disk? I'd >> like to try -current in a separate installation. > > Yes. The way I do it is to have a single fdisk partition containing > the entire disk (or more generally, as much of it as I want to use for > all OpenBSD stuff combined), then create two separate sets of OpenBSD > root, var, and usr partitions inside that, sharing /home. That is, > I have the following 'disklabel' partitions: > wd0a root #1 /etc/fstab mounts root #1, var #1, usr #1, home > wd0b swap > wd0c entire disk > wd0d root #2 /etc/fstab mounts root #2, var #2, usr #2, home > wd0e var #1 > wd0f var #2 > wd0g usr #1 > wd0h usr #2 > wd0j home > > I use the standard OpenBSD bootloader, so by default the computer boots > system #1. If I want to boot system #2, I just type "boot wd0d:/bsd" at > the "boot>" prompt. > > Note that the system #1 /etc/fstab mounts *only* the system #1 partitions > and home: > % cat /etc/fstab > /dev/wd0a / ffs rw,softdep 1 1 > /dev/wd0b /tmp mfs rw,async,nodev,nosuid,-s=2000000 0 0 > /dev/wd0e /var ffs rw,softdep,nodev,nosuid 1 2 > /dev/wd0g /usr ffs rw,softdep,nodev 1 2 > /dev/wd0b /usr/tmp mfs rw,async,nodev,nosuid,-s=2000000 0 0 > /dev/wd0j /home ffs rw,softdep,noatime,nodev,nosuid 1 2 > > Similarly, the system #2 /etc/fstab mounts *only* the system #2 partitions > and home: > # mount -r /dev/wd0d /mnt > # cat /mnt/etc/fstab > /dev/wd0d / ffs rw,softdep 1 1 > /dev/wd0b /tmp mfs rw,async,nodev,nosuid,-s=2000000 0 0 > /dev/wd0f /var ffs rw,softdep,nodev,nosuid 1 2 > /dev/wd0h /usr ffs rw,softdep,nodev 1 2 > /dev/wd0b /usr/tmp mfs rw,async,nodev,nosuid,-s=2000000 0 0 > /dev/wd0j /home ffs rw,softdep,noatime,nodev,nosuid 1 2 > # > > The two OpenBSD installations are entirely separate, and may be as > different as desired. (For example, the laptop on which I'm typing > this has #1 = 4.6-stable and #2 = 4.4-stable.) > > > A couple of important notes if you decide to try this: > > First, the standard OpenBSD install hard-codes "a" as the root partition. > So... at the "(I)nstall, (U)pgrade or (S)hell?" prompt, type "s" to get > a shell, then > # ed install.sub > $-1 (go to the 2nd-to-last-line) > s/a/d/ (change the 'a' to a 'd') > w (write the memory buffer back to the file) > q (quit the ed editor) > (maybe follow with 'more install.sub' to confirm that all went well) > OpenBSD will how happily install with root on the wd0d partition. > > [An alternative is to install what you want to wind up in #2 to the #1 > partitions, use dump|restore or tar|tar to copy these to the #2 partitions > (as per FAQ 10.2), run installboot(8) to fixup booting to the #2 partitions, > then reinstall what you really want to #1.] > > > Finally, and most important of all, *don't* try this unless you know > what you're doing! Playing around with partitions this way works fine > if you do things correctly, but mistakes can easily scramble your disk > (more accurately, the data on it). In particular, don't try this until > you grok the FMs disklabel(8), fstab(5), installboot(8). And have a > full backup *before* you try it... > > -- > -- "Jonathan Thornburg [remove -animal to reply]" <jth...@astro.indiana-zebra.edu> > Dept of Astronomy, Indiana University, Bloomington, Indiana, USA > "If the triangles made a god, it would have three sides." -- Voltaire > >
I believe Josh Grosse has the right idea - if your system supports booting of USB drives, $5 will buy a 1gb stick that is more than adequate for running OpenBSD on. -- Aaron Mason - Programmer, open source addict I've taken my software vows - for beta or for worse
