Re: shutting down/removing a software RAID array?

Dances With Crows wrote:
Gary Dale staggered into the Black Sun and said:
I've been looking for [how to *stop*] a [softRAID] in Linux.

"mdadm misc /dev/mdN --stop" . This won't work if /dev/mdN is mounted.

I can't get the RAID to cease to exist. My current state after redoing
the dd is shown by this:
#cat /proc/mdstat
Personalities : [raid1]
md1 : active raid1 hdc[1]
60696128 blocks [2/1] [_U]

Somewhere along the line I must have inadvertently added /dev/hdc to
the md1 array instead of /dev/hdc3.

If you're sure that you don't want to have any softRAID at all, change
the partition type of all former softRAID partitions to something other
than 0xfd. And rm -rf /etc/mdadm* while you're at it. (You can
regenerate that dir structure when you rebuild your softRAID setup
properly.) And check /proc/cmdline to make sure that you're not passing
"root=/dev/md1" or something to the kernel on boot. Also remember that
the md superblock info is stored at the *end* of the partition, so
efficiently erasing that info with dd will require a seek= .

And after trying everything else I can think of to remove the software
traces of the RAID array, a reboot still gives me md1 containing hdc.

Expand on "everything else you can think of". What, precisely, were the
commands you executed?

I've already done almost everything you suggested and more. I'd turned the partitions back to type 83 but that doesn't work on /dev/hdc - it's a device not a partition. Can you expand on the "seek=" however? Apparently the dd between devices didn't clobber whatever is making the computer think it's got RAID.

I tried zeroing the superblocks but that gave problems because mdadm won't touch a running RAID volume, which /dev/hdc is part of.

I uninstalled mdadm (with --purge) then removed everything that looked like an mdadm configuration file. There is nothing in /boot/grub/menu.lst that refers to /dev/md1. Still the RAID array show up.
.

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