mdadm: created as /dev/md0, becomes /dev/md127 after reboot.

-- lsb_release -rd
Description: Ubuntu precise (development branch)
Release: 12.04
--

-- apt-cache policy mdadm
mdadm:
  Installed: 3.2.3-2ubuntu1
  Candidate: 3.2.3-2ubuntu1
  Version table:
 *** 3.2.3-2ubuntu1 0
        500 http://us.archive.ubuntu.com/ubuntu/ precise/main amd64 Packages
        100 /var/lib/dpkg/status
--

-- Environment
Ubuntu 12.04 Server Edition 64bit (installed from the 20120323 daily ISO)
Installed into a guest running on VirtualBox 4.1.10, hosted on Windows 7.
Disk configuration:
1 SATA controller
1 20GB HDD (used at / mount point)
5x 512MB HDD (used to simulate RAID5 array)
--

-- What action I took
On an untouched installation, I install mdadm, and attempt to create a RAID5 array with this command:

sudo mdadm --create /dev/md0 --level=5 --raid-devices=5 /dev/sdb /dev/sdc /dev/sdd /dev/sde /dev/sdf

After confirming that I wanted to create the array, mdadm reported success. I initialized a file system on it, mounted it, and created a simple text file containing 'Hello World' on it. Then, I reboot.
--

-- What I expected to happen
mdadm would reassemble the array at boot time as /dev/md0.
--

-- What happened instead
mdadm reassemled the array at boot time as /dev/md127.
--

It took a great deal if hunting around to discover that the array had actually been assembled. I forget what command I issued that finally tipped me off to the existence of the assembled array, but running 'sudo mdadm --detail /dev/md127' confirmed that it was the array I had just built. I mounted the array and viewed the contents of the text file to confirm.

This did not occur when I built my array on my test and production servers running Ubuntu 10.04 Server 64bit, so I am calling this new and unexpected behavior, and filing it as a bug.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: mdadm 3.2.3-2ubuntu1
ProcVersionSignature: Ubuntu 3.2.0-20.32-generic 3.2.12
Uname: Linux 3.2.0-20-generic x86_64
ApportVersion: 1.95-0ubuntu1
Architecture: amd64
CurrentDmesg:

Date: Sat Mar 24 11:05:07 2012
InstallationMedia: Ubuntu-Server 12.04 LTS "Precise Pangolin" - Alpha amd64 (20120323)
MDadmExamine.dev.sda: Error: command ['/sbin/mdadm', '-E', '/dev/sda'] failed with exit code 1: mdadm: cannot open /dev/sda: Permission denied
MDadmExamine.dev.sda1: Error: command ['/sbin/mdadm', '-E', '/dev/sda1'] failed with exit code 1: mdadm: cannot open /dev/sda1: Permission denied
MDadmExamine.dev.sda2: Error: command ['/sbin/mdadm', '-E', '/dev/sda2'] failed with exit code 1: mdadm: cannot open /dev/sda2: Permission denied
MDadmExamine.dev.sda5: Error: command ['/sbin/mdadm', '-E', '/dev/sda5'] failed with exit code 1: mdadm: cannot open /dev/sda5: Permission denied
MDadmExamine.dev.sdb: Error: command ['/sbin/mdadm', '-E', '/dev/sdb'] failed with exit code 1: mdadm: cannot open /dev/sdb: Permission denied
MDadmExamine.dev.sdc: Error: command ['/sbin/mdadm', '-E', '/dev/sdc'] failed with exit code 1: mdadm: cannot open /dev/sdc: Permission denied
MDadmExamine.dev.sdd: Error: command ['/sbin/mdadm', '-E', '/dev/sdd'] failed with exit code 1: mdadm: cannot open /dev/sdd: Permission denied
MDadmExamine.dev.sde: Error: command ['/sbin/mdadm', '-E', '/dev/sde'] failed with exit code 1: mdadm: cannot open /dev/sde: Permission denied
MDadmExamine.dev.sdf: Error: command ['/sbin/mdadm', '-E', '/dev/sdf'] failed with exit code 1: mdadm: cannot open /dev/sdf: Permission denied
MachineType: innotek GmbH VirtualBox
ProcEnviron:
 TERM=xterm
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.2.0-20-generic root=/dev/mapper/hostname-root ro
SourcePackage: mdadm
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 12/01/2006
dmi.bios.vendor: innotek GmbH
dmi.bios.version: VirtualBox
dmi.modalias: dmi:bvninnotekGmbH:bvrVirtualBox:bd12/01/2006:svninnotekGmbH:pnVirtualBox:pvr1.2:
dmi.product.name: VirtualBox
dmi.product.version: 1.2
dmi.sys.vendor: innotek GmbH
etc.blkid.tab: Error: [Errno 2] No such file or directory: '/etc/blkid.tab'