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

[Matt Brock]

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.
>>
>> Cheers,
>>
>> Matt.
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