On Tue, Jun 18, 2013 at 11:42 AM, Caspar Smit [off-list ref] wrote:

Hi Mark,

Stopping an MD device will not remove/delete anything.
The --remove command cannot be used AFTER an MD device is stopped.
(--remove is only for removing drives/partitions from a running MD
device NOT to remove the MD itself e.g. mdadm --remove /dev/mdX
/dev/sdb, furthermore a drive/partition can only be removed after you
fail the drive first or it has failed by itself offcouse, see the
--fail switch)

To completely erase the MD you need to stop it and then remove the
superblocks from the member drives:

mdadm --stop /dev/md127
mdadm --zero-superblock /dev/sdb5
mdadm --zero-superblock /dev/sdc5
mdadm --zero-superblock /dev/sdd5

You can combine the last 3 commands to:

mdadm --zero-superblock /dev/sd[b-d]5

but to be 100% safe use them seperately.

This will erase the superblocks on the members of /dev/md127 and you
will not be able to assemble it again and it will not be started
during a reboot (remove it from the mdadm.conf too offcourse, but
since the array comes up as /dev/md127 I presume it is already not
present in mdadm.conf)

Kind regards,
Caspar

Thanks Caspar. What you are saying makes more sense to me and is, as
best I can tell, consistent with man mdadm.

I've used this site a few times as it seems to come up a lot when
Googling mdadm questions:

http://www.ducea.com/2009/03/08/mdadm-cheat-sheet/

Apparently his instructions in #3 are incorrect.

Cheers,
Mark

2013/6/18 Mark Knecht [off-list ref]:

<SNIP>

quoted

mdadm --stop /dev/md127
mdadm --remove /dev/md127

to remove the raid1?

<SNIP>