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[SLUG] Linux multi disc booting story, tips



In case this is of any use to anyone...

Last week I bought a new PC and loaded RH7.1 on it.  The significant
thing was that I bought 2 40Gb ATA100 drives for RAID mirroring, for
extra reliability, and I got a motherboard with 4 IDE controllers,
since my plan was to transfer the 2 old disc drives from the previous
system into the new one, so I could migrate things across gradually,
and re-do umpteen configuration things at my leisure.

I also put each of the 40Gb drives on a separate IDE controller (ide0
and ide1), for best performance.

Then I discovered that PC BIOSes won't let you boot off any but the 1st
2 IDE drives.

Anyway, Bin Liao told me the trick to getting it all working as I
wanted.  In the BIOS, change the boot options so that it will try to
boot SCSI deviices before IDE devices.  That's because the UDMA ATA100
drives are treated by the BIOS as if they're SCSI, in some sense, so the
next 2 IDE drives look to it like they're the first ones.

After that, it was just a matter of editing /etc/fstab to  put in
entries for the old drives, edit the /etc/fstab on one of the old
drives to use the new drive lettering (e.g. /dev/hda became hdg, hdb
became hdh).  The new RH7.1 kernel is on /dev/md1 (/dev/md0 is a swap
partition), and the old kernels and RH installs of course are on the old
discs.

Then I made the same changes in /etc/lilo.conf, set it to boot off the
MBR of /dev/hda (one of the new mostly-mirrored 40Gb drives).  It
booted up the old RH6.2 system as far as checking the partitions, then
panicked because it couldn't mount the root filesystem.

>From the boot messages, though, it was clear that the old system had
only seen ide0 and ide1, not ide2 or ide3.  So I rebooted the new
system, noted down the IO addresses and IRQ details for those
interfaces, and put in the appropriate at the lilo boot prompt
(ide2=<ioaddr>,<ioaddr>,<irq> ide3=...) for each of the drives, and
bingo!  all worked fine.

One note - I (have to have) a Win98 system there, so I made the 1st
partition a Windows one on each of the 2 RAID drives, and those
partitions are not mirrored.  The rest are.  The RAID setup on RH7.1
was trivially easy - very smooth.

BTW, is there a trick to copying a Windows installation from one
partition to another?  I tried copying one Win98 system partition to an
empty one and booting off that at one stage, but it hung before going
fully graphical (i.e., splash screen, flash back to console mode, load
a few drivers, then the flash back to graphical mode and finish booting
failed).  All partitions on both 40Gb drives start and end on exaclty
the same cylinders.

Is there some specific block size one should specify for the dd copy,
perhaps?  I know there was a restriction like that when copying floppy
discs of other OSes.

luke



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