[mythtv-users] Mirroring via LVM or RAID?

[chris at cpr.homelinux.net]

On Sat, Jul 08, 2006 at 02:45:57AM -0500, Sage wrote:
> Chris's claim is that lilo will install on both disks automatically --

Automatic, but not automagic. :-)

If you put the lines
	boot=/dev/md0
	raid-extra-boot=/dev/hda,/dev/hdc
into lilo.conf then it knows that your md0 array is located on two 
drives (note that you specify the array's drives, not the 
partitions) and will automatically figure out which partitions are 
involved and update both boot records.

> I wasn't aware of this, but I suspect that lilo may be installing onto
> the actual boot partition instead of the master boot record.

Indeed.  Installing to the MBR is strongly discouraged no matter 
whether you're using lilo or grub (because the MBR is so easily 
damaged), and in the case of a raid array might not work anyway 
because there's no guarantee that the two partitions in the array 
are located at the same physical offset on both drives.  If you put 
lilo's boot information in the partition boot sectors and mark the 
appropriate partition as bootable on both drives then you can use a 
vanilla MBR and the drives are swappable.