On Fri, 4 Dec 2009 14:04:30 +1100 Aaron Mason <[email protected]> wrote:
> On Fri, Dec 4, 2009 at 12:33 PM, Jonathan Thornburg > <[email protected]> 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]" > <[email protected]> > > 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. > OK, I get it. I thought root always had to be 'a'. But being able to use the same disklabel for both installations is even better than using two separate disklabels. Thanks for the hints and tips! Christopher
