Well, I think I should be able to boot off the mirror disk without removing the primary disk, after all, I can do that with Windows XP, which is the 3rd disk in the system.
But I did try that anyway and got the dreaded Error 22 for the thousand and one time.


I think this looks better:

# eeprom altbootpath=/pci@0,0/pci10de,376@a/pci1000,3150@0/sd@1,0:a

#: eeprom | grep -i bootpath
bootpath=/pci@0,0/pci10de,376@a/pci1000,3150@0/sd@0,0:a
altbootpath=/pci@0,0/pci10de,376@a/pci1000,3150@0/sd@1,0:a


BTW, found this line for x86, doesn't work either, neither file exists on my system:

# installboot /usr/platform/i86pc/lib/fs/ufs/pboot /usr/platform/i86pc/lib/fs/ufs/bootblk /dev/rdsk/${MIR_DISK}s2

#: ll /usr/platform/i86pc/lib/fs/ufs/pboot /usr/platform/i86pc/lib/fs/ufs/bootblk
/usr/platform/i86pc/lib/fs/ufs/pboot: No such file or directory
/usr/platform/i86pc/lib/fs/ufs/bootblk: No such file or directory

Update:

I was able to boot off the mirror disk, which was specified in the /grub/boot/menu.lst file.

Now question, just to be completely sure, how do I know which disk I booted off? Is there anything in the system logs that says "I booted off MIRROR disk and not primary"?

I did yank out the primary disk, tried to boot off mirror and went back to the Error 22 above.

How do I validate that the mirror disk is bootable? Can I swap primary and mirror disks and just let it boot?