Hello all, There is probably a simple answer to this, so I apologize if this is a stupid question.

I am running Ubuntu Server 13.10 with just the CLI. I am trying to create a RAID1 array using two 4TB drives. None of them are the boot drive. I have a 500GB that has my boot and systems files. I installed Mdadm and formatted the drives using GParted since I needed 4TB partitions. The output of fdisk -l is below. My problem is when I go to create an array, it informs me that /dev/sdb1 is already part of another array. It says that the array is a RAID0 with 0 devices. I did previously create another array successfully, but when I formatted the array, but could not get Ubuntu to boot when I restarted. However, it wasn't a RAID0. It was a RAID1 like I am trying to create now. It then tells me that if I continue the partition table on the drive will be lost when it's added to the this new array. That's fine since I don't know what array they are talking about. I tell it to continue and it says

"mdadm: failed to open /dev/sdb1 after earlier success - aborting"

Here is the output from fdisk -l, /etc/mdadm/mdadm.conf, and /proc/mdstat. I apologize that do not have the output from trying to create the array, but I could not find a way to send the output to a text file and allow me say Yes to continuing. If someone could tell me how to that, that would be much appreciated as well. Thank you so much!

P.S. How do you put the output/commands in a nice code box like other posters do? Thanks.


Disk /dev/sda: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0007836c

Device Boot Start End Blocks Id System
/dev/sda1 * 2048 964218879 482108416 83 Linux
/dev/sda2 964220926 976771071 6275073 5 Extended
/dev/sda5 964220928 976771071 6275072 82 Linux swap / Solaris


Disk /dev/sdb: 4000.8 GB, 4000787030016 bytes
255 heads, 63 sectors/track, 486401 cylinders, total 7814037168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x00000000

Device Boot Start End Blocks Id System
/dev/sdb1 1 4294967295 2147483647+ ee GPT

Partition 1 does not start on physical sector boundary.


Disk /dev/sdc: 4000.8 GB, 4000787030016 bytes
255 heads, 63 sectors/track, 486401 cylinders, total 7814037168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x077377da

Device Boot Start End Blocks Id System
/dev/sdc1 1 4294967295 2147483647+ ee GPT

Partition 1 does not start on physical sector boundary.

----------------------------------------------------------------------------------

# mdadm.conf
#
# Please refer to mdadm.conf(5) for information about this file.
#

# by default (built-in), scan all partitions (/proc/partitions) and all
# containers for MD superblocks. alternatively, specify devices to scan, using
# wildcards if desired.
#DEVICE partitions containers

# auto-create devices with Debian standard permissions
CREATE owner=root group=disk mode=0660 auto=yes

# automatically tag new arrays as belonging to the local system
HOMEHOST <system>

# instruct the monitoring daemon where to send mail alerts
MAILADDR root

# definitions of existing MD arrays

# This file was auto-generated on Sat, 21 Dec 2013 11:20:35 -0500
# by mkconf $Id$

----------------------------------------------------------------------
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]

unused devices: <none>

Did you run "mdadm --zero-superblock /dev/sd$XYZ" on the disk that was in another array?

It sounds like you tried to boot off a software RAID. It can be error prone and results vary with hardware and boot stack.