On Fri, 2006-06-09 at 23:19 +0800, Feizhou wrote: > > > >>>I just looked at the boot sector on the 3 machines that I have running > >>>software raid1. It looks like the installer got it right on all 3. > >>>IIRC, one was installed as CentOS 4.1, another as 4.2, and another as 4.3. > >> > >>The installer will install grub. Just not properly. If the first disk > >>dies, when the box comes up, the previous second disk grub stage 1 will > >>load but it will not look for the stage 2 on the current disk and > >>therefore fail. > > > > > > That will depend on what your bios does when the first drive fails and > > whether you've had to move it to make it boot at all. On the scsi > > systems where I've used it, the 2nd drive will boot and everything > > on the cable shifts up if the first drive fails or is removed. > > IDE systems are different - and normally won't boot if a failed drive > > is still connected. > > > > Hmm, does it come back up on a scsi based system? Mine does but it may depend on the bios. > I cannot remember but if the second disk's grub stage 1 does get loaded, > it tries to load stage 2 from the 'second' drive which will not work and > the reason for the failure or whether it does load stage2 but stage2 > looks in the wrong 'disk' for its config file. > > So either way, it should also fail on a scsi system... These seem to shift the first working drive into the first bios drive as well as /dev/sda. The same disk will boot whether I put it in the 1st or 2nd (SCA hot-swap) slot. I have noticed that some newer machines must be configured specifically for the slot to use when booting and are even unhappy if you swap in a different drive type in the same slot without reconfiguring the bios boot selection so this may vary a lot among machines. I did the grub setup by hand but have noticed that there are different sets of instructions around that apply to IDE drives. In any case, I think it is a good idea to keep a rescue CD handy and understand how to re-install grub. -- Les Mikesell lesmikesell at gmail.com