Re: After partition resize, RAID5 array does not assemble on boot

[Jules Bean <jules@jellybean.co.uk>]

Jules Bean wrote:
> Help? What next ;) Is there enough information in /dev/sdd2 and 
> /dev/sdc2 to reconstruct the apparently missing superblocks on /dev/sda2 
> and /dev/sdb2? Do I need to try to resize my partitions back to their 
> old size so it can find the old superblock? Even if by adding /dev/sda2 
> as a spare I've corrupted its superblock entirely, sdb2 should still 
> have enough to save my array with 3 out of 4 devices?

I have become convinced (correct me if you think I'm wrong) that the 
problem was cfdisk resizing the partitions but the kernel tables not 
being updated.

Therefore although I thought the partitions were 400G, the kernel still 
thought they were 250G, and presumably the raid subsystem used that figure.

So the raid subsytem probably recorded its superblock as if the 
partitions were still only 250G long? So I ought to be able to find that 
superblock again by resizing the partitions back?

Alas I didn't take precise notes of my old partition table (stupid 
error). I have tried a couple of cylinder counts near 250G but no luck. 
Is there any good way to 'search for' somethign which looks like a RAID 
superblock?

Does the mdadm --detail output I pasted in my last message hold any clues?

Jules