From mboxrd@z Thu Jan  1 00:00:00 1970
From: starlight.2012q4@binnacle.cx
Subject: Re: question: no-bitmap RAID1 with off-site drive
Date: Sun, 11 Nov 2012 17:14:03 -0500
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Would like to have the option to zero the
superblock of an incoming drive and have
it treated as a virgin replacement.

I tried this (I think) by running

   mdadm --add /dev/md2 /dev/sde

It worked, but assigned the new drive
as device number [2], which seems
incorrect.  I tried failing/removing the
drive followed by a

   mdadm --remove /dev/md2 detached

and repeated the --add with a zero-superblock
drive but it does the same thing every time.
Only way to get it to reuse drive slot 1
was to do a 

   mdadm --grow --raid-devices=1 --force /dev/md2

followed by a

   mdadm --grow --add --raid-devices=2 /dev/md2 /dev/sde

Is this the expected behavior?  I find it
confusing and probably don't understand
it properly.

Kernel is 3.1.8.