Re: Deleting mdadm RAID arrays

Neil Brown wrote:

On Tuesday February 5, admin@domeny.pl wrote:
  

quoted

% mdadm --zero-superblock /dev/sdb1
mdadm: Couldn't open /dev/sdb1 for write - not zeroing
    

That's weird.
Why can't it open it?

  

I suspect that (a) he's not root and has read-only access to the device (I have group read for certain groups, too). And since he had the arrays on raw devices, shouldn't he zero the superblocks using the whole device as well? Depending on what type of superblock it might not be found otherwise.

It sure can't hurt to zero all the superblocks of the whole devices and then check the partitions to see if they are present, then create the array again with --force and be really sure the superblock is present and sane.

Maybe you aren't running as root (The '%' prompt is suspicious).
Maybe the kernel has  been told to forget about the partitions of
/dev/sdb.
mdadm will sometimes tell it to do that, but only if you try to
assemble arrays out of whole components.

If that is the problem, then
   blockdev --rereadpt /dev/sdb

will fix it.

NeilBrown

-- 
Bill Davidsen [off-list ref]
 "Woe unto the statesman who makes war without a reason that will still
 be valid when the war is over..." Otto von Bismark