[ydl-gen] Software RAID - making the spare bootable

[Bill Fink]

Matt,

If the root filesystem in /etc/fstab is being mounted via UUID,
then the new disk is going to have a different UUID.  I use the
LABEL option instead after having labelled the partition, but
I don't know if that would work with your RAID configuration.

Perhaps this info might help you.

					-Bill



On Fri, 17 Dec 2010, Matt Brock wrote:

> Yes, that's exactly right. The spare is set up in just that way, and  
> when I bring it into the array it works fine as the second disk once  
> the sync process is completed. The only problem is that I can't get  
> the server to boot off that new second disk, and that's what's  
> frustrating me.
> 
> On 14 Dec 2010, at 22:05, Derick Centeno wrote:
> 
> > Question:
> > Correct me if I missed something, but wasn't the third "spare"  
> > intended to be an exact mirror so that it could replace either the  
> > first or second drive?
> >
> > For the "spare" to be a replacement for either the first or the  
> > second drive it also would have matched the exact partition  
> > structure of the first two.  In this particular sense the "spare" is  
> > really no "spare" at all, but a sort of emergency last ditch fail- 
> > safe in the event that either the first or second drive failed.   
> > This also means that the for the RAID 1 system to function with a  
> > fail-safe option/strategy the third drive had to be prepared  
> > properly so that it could potentially replace any one of the other  
> > two at any time.
> >
> > Zeroing the RAID superblocks and attempting to make the Apple  
> > partition bootable via ybin may have been mistakes; however the  
> > strategy to dd the second (or first) drive onto the "spare" appears  
> > reasonable.
> >
> > Is it possible to reformat/restructure all three disks, using YDL,  
> > so that function is restored?
> >
> > On 12/13/10 2:37 PM, Matt Brock wrote:
> >> Hi there.
> >>
> >> (I posted this onto the YDL forums earlier today, so apologies to  
> >> anyone who's seen it twice.)
> >>
> >> I've been using YDL on Xserve G5s for a couple of years now and it  
> >> does a great job. Recently I decided to rebuild one with software  
> >> RAID to get disk redundancy. I did all of this through the  
> >> installer. The server has three disks, so I set them up as RAID 1  
> >> with a spare.
> >>
> >> This has all gone very successfully apart from one detail. The two  
> >> disks in the RAID set are bootable, i.e. I can remove either of  
> >> those disks and the machine will still boot as normal. That's fine  
> >> so far. Then I permanently removed the first disk and brought the  
> >> spare third disk into the RAID set instead. Once the RAID set is  
> >> then fully rebuilt I can boot off the original second disk, but the  
> >> third disk which was previously the spare disk is not bootable. It  
> >> gets to the first yaboot stage, and then the blue icon which  
> >> represents OpenBoot failing to find a boot disk appears  
> >> superimposed over the yaboot screen. That process just loops over  
> >> and over again and never boots.
> >>
> >> I've tried using ybin to make the Apple boot partition bootable  
> >> with the correct yaboot config, but that didn't help. I've tried dd- 
> >> ing the entire second disk onto the third disk then zeroing the  
> >> RAID superblocks, and that didn't work. I've tried resetting the  
> >> NVRAM and that made no difference. I'm sure it's not a hardware  
> >> problem with the disk because I've tried this twice now with the  
> >> disks in different slots each time, and it's always the spare disk  
> >> which has the boot problem even though that's a different physical  
> >> disk each time.
> >>
> >> I hope there's someone out there who can help because I'm tearing  
> >> my hair out over this. I can't see what else would be needed to  
> >> make the third disk bootable... yet there must be something!  
> >> Without getting this working the full redundancy I'd hoped for  
> >> can't be achieved, which would be extremely frustrating.