On Mon, Sep 15, 2008 at 05:04:39PM +0100, Russell Howe wrote: > Johan Strvm wrote, sometime around 15/09/08 16:39: : : > > > >Yep, thats my plan too (or well 250G since 250G is almost as cheap as > >80G, and we are using 250G in other machines, no need for different > >spares), and use software raid. One thing I'm worried about though is if > >one disk fails, will the BIOS be able to boot from the other disk with a > >broken/empty disk in the first slot? I haven't seen any indications in > >the BIOS about being able to change, and I've had similar problems > >before (empty disk in slot1, disk with OS in slot2, box refusing to boot > >since disk1 is empty). > > I don't think this will work with the way I have it set up at present. > The trick on Linux is to install the bootloader on disk 2 so that it is > configured to boot from disk 1 (as disk #2 will become disk #1 when disk > #1 is no longer there or operational). I haven't tried to figure out the > necessary magic for that as yet.
I have done this on a DL140 G3 with OpenBSD 4.1. I hope now with OpenBSD 4.4 that RAIDFrame autoconfigured root disk is up and working again. In 4.3 I recall it was broken, There is not much magic involved. Both disks have an partition 'a' that contain /boot and /bsd (RAID enabled). You have to run /usr/mdec/installboot on them (there is a bit of magic) to install the boot sector and point it to /boot on the disk. If you remove disk #1 the BIOS finds disk #2 and uses its boot sector. It loads /boot that finds the disk it is on and loads /bsd, which in its turn is RAID autoconfig enabled and finds the broken rootdisk mirror that the lonely disk #2 is. If you put a clean disk as #1 I am not dead sure what the BIOS does. It should try to boot disk #2 if there is no boot sector on #1. Then you can partition the disk and restore the mirror, plus recreate the 'a' partition and boot sector. That was only the minimal way. I have in fact complete small installations on both 'a' partitions i.e the installation used to compile the RAID kernel, plus a /etc/boot.conf file, and /bsd, /bsd.old /bsd.raid /obsd kernels, so it is possible to keyboard control /boot and order it to boot a non-RAID-aware system just in case. In the RAID drive the /etc/fstab has mount points for /dev/wd0a and /dev/wd1a so they can be mounted to copy new kernels and run /usr/mdec/installboot on them whenever /boot changes or moves. > > -- > Russell Howe, IT Manager. <[EMAIL PROTECTED]> > BMT Marine & Offshore Surveys Ltd. -- / Raimo Niskanen, Erlang/OTP, Ericsson AB
