Is that really what I'm supposed to do, given that syslinux is on the other
drive? Like I say, it seems wrong to me, but I really don't know. And if
that's not what I'm supposed to do, what is the right set of commands?
syslinux aka extlinux aka isolinux is most widely know as the
bootloader for bootable CDs
but it's a fairly robust bootloader and can be used for harddrives too.
if your /boot is on a ext2/3/4/btrfs filesystem you can use extlinux.
see here http://www.syslinux.org/wiki/index.php/EXTLINUX about RAID-1
it suggests a separate /boot partition which I'm not sure is a
requirement so maybe you can test it
make sure you install the syslinux mbr to both of the hard drive
devices.
that grub thing in the wiki page is maybe a sloppy copy/paste or
leftover edit - but I didn't read the wiki
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дамјан