[NCLUG] RAID array not started on re-boot

[Stephen Warren]

On 09/10/2013 01:26 PM, Kevin Olson wrote:
> I will try the suggestion of the mdadm --zero-superblock on the /dev/sda in
> the near futur

That may well solve the problem, and indeed is a good solution, but one
caveat:

Make sure you have a good backup of the entire raw disk first! Or, that
you can restore all the data from a backup, on a freshly re-created
array and filesystem.

I don't recall how far into a block device the RAID super-block is, nor
how large of a chunk of data zeroing a RAID superblock will write. If
it's a little way in, and /dev/sda1 starts near the start of /dev/sda,
then a write a little way into into /dev/sda might also be a write a
little way (slightly less) into /dev/sda1, and hence you may end up
trashing some data that you want to keep.