In article 20190225050144.GA5984@button.barrett.com.au, Jobst Schmalenbach jobst@barrett.com.au wrote:
Hi.
CENTOS 7.6.1810, fresh install - use this as a base to create/upgrade new/old machines.
I was trying to setup two disks as a RAID1 array, using these lines
mdadm --create --verbose /dev/md0 --level=0 --raid-devices=2 /dev/sdb1 /dev/sdc1 mdadm --create --verbose /dev/md1 --level=0 --raid-devices=2 /dev/sdb2 /dev/sdc2 mdadm --create --verbose /dev/md2 --level=0 --raid-devices=2 /dev/sdb3 /dev/sdc3
then I did a lsblk and realized that I used --level=0 instead of --level=1 (spelling mistake) The SIZE was reported double as I created a striped set by mistake, yet I wanted the mirrored.
Here starts my problem, I cannot get rid of the /dev/mdX no matter what I do (try to do).
I tried to delete the MDX, I removed the disks by failing them, then removing each array md0, md1 and md2. I also did
dd if=/dev/zero of=/dev/sdX bs=512 seek=$(($(blockdev --getsz /dev/sdX)-1024)) count=1024 dd if=/dev/zero of=/dev/sdX bs=512 count=1024 mdadm --zero-superblock /dev/sdX
Then I wiped each partition of the drives using fdisk.
The superblock is a property of each partition, not just of the whole disk.
So I believe you need to do:
mdadm --zero-superblock /dev/sdb1 mdadm --zero-superblock /dev/sdb2 mdadm --zero-superblock /dev/sdb3 mdadm --zero-superblock /dev/sdc1 mdadm --zero-superblock /dev/sdc2 mdadm --zero-superblock /dev/sdc3
Cheers Tony