View source for Ubuntu Workstation w/ RAID1

== Background Information ==

I wanted to run a desktop with two drives in RAID 1 (Mirroring) mode for data protection.  Red Hat and CentOS support the hardware RAID controller, but Ubuntu, Mint and Debian Workstations do not, and do not natively support the software RAID.  The instructions below are how I overcame the Workstation limitation.

== Hardware Configuration ==

Ensure that you start with 2 drives of equal size, and that they are not configured for hardware RAID.

== Boot from Ubuntu install disc in "Live" mode==

There are many steps before you get to run the installation program, so make sure that you are running in the "Live" or "try is out" mode.

== Start terminal window ==

== Become root ==

 ubuntu@ubuntu ~ $ sudo su -
 
 ubuntu ~ # 
 
== Install mdadm package ==

 ubuntu ~ # apt-get install mdadm
 
 Reading package lists... Done
 Building dependency tree       
 Reading state information... Done
 Recommended packages:
   default-mta mail-transport-agent
 The following NEW packages will be installed:
   mdadm
 0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
 Need to get 520 kB of archives.
 After this operation, 1,190 kB of additional disk space will be used.
 Get:1 http://archive.ubuntu.com/ubuntu/ saucy/main mdadm amd64 3.2.5-5ubuntu2 [520 kB]
 Fetched 520 kB in 1s (378 kB/s)
 Preconfiguring packages ...
 Selecting previously unselected package mdadm.
 (Reading database ... 162316 files and directories currently installed.)
 Unpacking mdadm (from .../mdadm_3.2.5-5ubuntu2_amd64.deb) ...
 Processing triggers for ureadahead ...
 Processing triggers for man-db ...
 Processing triggers for doc-base ...
 Processing 38 changed doc-base files, 6 added doc-base files...
 Registering documents with scrollkeeper...
 Setting up mdadm (3.2.5-5ubuntu2) ...
 Generating mdadm.conf... done.
  Removing any system startup links for /etc/init.d/mdadm-raid ...
 update-initramfs is disabled since running on read-only media
  * Starting MD monitoring service mdadm --monitor                        [ OK ] 
 Processing triggers for ureadahead ...

== For existing RAID Installations ==

=== Scan for existing RAID setup ===

 ubuntu ~ # mdadm --assemble --scan
 
 mdadm: /dev/md/0 has been started with 2 drives.
 mdadm: /dev/md/1 has been started with 2 drives.
 
=== Check the detail on the assembled RAID devices ===

 ubuntu ~ # mdadm --detail /dev/md0
 
 /dev/md0:
         Version : 1.2
   Creation Time : Mon Apr 21 11:46:38 2014
      Raid Level : raid1
      Array Size : 127360 (124.40 MiB 130.42 MB)
   Used Dev Size : 127360 (124.40 MiB 130.42 MB)
    Raid Devices : 2
   Total Devices : 2
     Persistence : Superblock is persistent
 
     Update Time : Tue Apr 22 13:55:33 2014
           State : clean 
  Active Devices : 2
 Working Devices : 2
  Failed Devices : 0
   Spare Devices : 0
 
            Name : ubuntu:0  (local to host ubuntu)
            UUID : 27f315b1:3e277fef:1a307b24:ea4df3eb
          Events : 19
 
     Number   Major   Minor   RaidDevice State
        0       8        1        0      active sync   /dev/sda1
        1       8       17        1      active sync   /dev/sdb1
 
 ubuntu ~ # mdadm --detail /dev/md1
 
 /dev/md1:
         Version : 1.2
   Creation Time : Mon Apr 21 11:46:17 2014
      Raid Level : raid1
      Array Size : 976502848 (931.27 GiB 999.94 GB)
   Used Dev Size : 976502848 (931.27 GiB 999.94 GB)
    Raid Devices : 2
   Total Devices : 2
     Persistence : Superblock is persistent
 
     Update Time : Tue Apr 22 13:53:14 2014
           State : clean 
  Active Devices : 2
 Working Devices : 2
  Failed Devices : 0
   Spare Devices : 0
 
            Name : ubuntu:1  (local to host ubuntu)
            UUID : 177d7ce2:924e598c:dc94b11a:58bc19c7
          Events : 26
 
     Number   Major   Minor   RaidDevice State
        0       8        2        0      active sync   /dev/sda2
        1       8       18        1      active sync   /dev/sdb2

=== Check for lvm configuration ===

 ubuntu ~ # lvdisplay 
 
   --- Logical volume ---
   LV Path                /dev/vg1/lv2
   LV Name                lv2
   VG Name                vg1
   LV UUID                eIkzAc-CE77-jRyT-KFAu-hez5-ebcz-1FFJ0M
   LV Write Access        read/write
   LV Creation host, time ubuntu, 2014-04-21 13:27:02 -0600
   LV Status              available
   # open                 2
   LV Size                4.00 GiB
   Current LE             1024
   Segments               1
   Allocation             inherit
   Read ahead sectors     auto
   - currently set to     256
   Block device           252:0
    
   --- Logical volume ---
   LV Path                /dev/vg1/lv1
   LV Name                lv1
   VG Name                vg1
   LV UUID                BOKjom-ftnd-Vj7P-BvX4-uhKw-0Fm1-u6OVNC
   LV Write Access        read/write
   LV Creation host, time ubuntu, 2014-04-21 13:28:43 -0600
   LV Status              available
   # open                 1
   LV Size                927.00 GiB
   Current LE             237312
   Segments               1
   Allocation             inherit
   Read ahead sectors     auto
   - currently set to     256
   Block device           252:1

== For new Ubuntu Installations ==

=== Zero Drives ===

Zero the first drive to ensure that the drive is empty.

 ubuntu ~ # dd if=/dev/zero of=/dev/sda bs=1048576
 
 dd: writing ‘/dev/sda’: No space left on device
 953870+0 records in
 953869+0 records out
 1000204886016 bytes (1.0 TB) copied, 6393.41 s, 156 MB/s
 

Also zero the second drive to ensure that it is empty.

 ubuntu ~ # dd if=/dev/zero of=/dev/sdb bs=1048576
 
 dd: writing ‘/dev/sdb’: No space left on device
 953870+0 records in
 953869+0 records out
 1000204886016 bytes (1.0 TB) copied, 5814.41 s, 172 MB/s
 

=== Partition Drives ===
'''*** NOTE:  You will want to increase the /boot partition from 128M to 256M.  128M will be too small to have more than one kernel installed, and this will cause you grief.'''

==== Option 1 fdisk ====

 ubuntu ~ # fdisk /dev/sda
 
 The device presents a logical sector size that is smaller than
 the physical sector size. Aligning to a physical sector (or optimal
 I/O) size boundary is recommended, or performance may be impacted. 
 
 Command (m for help): n
 Partition type:
    p   primary (0 primary, 0 extended, 4 free)
    e   extended
 Select (default p): p
 Partition number (1-4, default 1): 
 Using default value 1
 First sector (2048-1953525167, default 2048): 
 Using default value 2048
 Last sector, +sectors or +size{K,M,G} (2048-1953525167, default 1953525167): +128M
 
 Command (m for help): a
 Partition number (1-4): 1
 
 Command (m for help): n
 Partition type:
    p   primary (1 primary, 0 extended, 3 free)
    e   extended
 Select (default p): p
 Partition number (1-4, default 2): 
 Using default value 2
 First sector (264192-1953525167, default 264192): 
 Using default value 264192
 Last sector, +sectors or +size{K,M,G} (264192-1953525167, default 1953525167): 
 Using default value 1953525167
 
 Command (m for help): t
 Partition number (1-4): 1
 Hex code (type L to list codes): fd
 Changed system type of partition 1 to fd (Linux raid autodetect)
 
 Command (m for help): t
 Partition number (1-4): 2
 Hex code (type L to list codes): fd
 Changed system type of partition 2 to fd (Linux raid autodetect)
 
 Command (m for help): p
 
 Disk /dev/sda: 1000.2 GB, 1000204886016 bytes
 255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 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: 0x000780e2
 
    Device Boot      Start         End      Blocks   Id  System
 /dev/sda1   *        2048      264191      131072   fd  Linux raid autodetect
 /dev/sda2          264192  1953525167   976630488   fd  Linux raid autodetect
 
 Command (m for help): w
 The partition table has been altered!
 
 Calling ioctl() to re-read partition table.
 Syncing disks.

 ubuntu ~ # fdisk /dev/sdb
 
 The device presents a logical sector size that is smaller than
 the physical sector size. Aligning to a physical sector (or optimal
 I/O) size boundary is recommended, or performance may be impacted.
 
 Command (m for help): n
 Partition type:
    p   primary (0 primary, 0 extended, 4 free)
    e   extended
 Select (default p): 
 Using default response p
 Partition number (1-4, default 1): 
 Using default value 1
 First sector (2048-1953525167, default 2048): 
 Using default value 2048
 Last sector, +sectors or +size{K,M,G} (2048-1953525167, default 1953525167): +128M
 
 Command (m for help): a
 Partition number (1-4): 1
 
 Command (m for help): n
 Partition type:
    p   primary (1 primary, 0 extended, 3 free)
    e   extended
 Select (default p): 
 Using default response p
 Partition number (1-4, default 2): 
 Using default value 2
 First sector (264192-1953525167, default 264192): 
 Using default value 264192
 Last sector, +sectors or +size{K,M,G} (264192-1953525167, default 1953525167): 
 Using default value 1953525167
 
 Command (m for help): t
 Partition number (1-4): 1
 Hex code (type L to list codes): fd
 Changed system type of partition 1 to fd (Linux raid autodetect)
 
 Command (m for help): t
 Partition number (1-4): 2
 Hex code (type L to list codes): fd
 Changed system type of partition 2 to fd (Linux raid autodetect)
 
 Command (m for help): p
 
 Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes
 255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 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: 0x000b76e9
 
    Device Boot      Start         End      Blocks   Id  System
 /dev/sdb1   *        2048      264191      131072   fd  Linux raid autodetect
 /dev/sdb2          264192  1953525167   976630488   fd  Linux raid autodetect
 
 Command (m for help): w
 The partition table has been altered!
 
 Calling ioctl() to re-read partition table.
 Syncing disks.

==== Option 2 cfdisk ====
Partition the first drive

 ubuntu ~ # cfdisk /dev/sda
 

This prings up the menu-driven partitioning program.  You will set up 2 partitions, set the type to FD, set the first partition to be bootable, and then write the partition table.  The partitions should look similar to that below.

                            cfdisk (util-linux 2.20.1)
 
                               Disk Drive: /dev/sda
                       Size: 1000204886016 bytes, 1000.2 GB
              Heads: 255   Sectors per Track: 63   Cylinders: 121601
 
     Name        Flags      Part Type  FS Type          [Label]        Size (MB)
  ------------------------------------------------------------------------------
     sda1        Boot        Primary   Linux raid autodetect              131.61 
     sda2                    Primary   Linux raid autodetect          1000073.29*
 
 
 
 
 
 
 
 
 
 
      [ Bootable ]  [  Delete  ]  [   Help   ]  [ Maximize ]  [  Print   ]
      [   Quit   ]  [   Type   ]  [  Units   ]  [  Write   ]
                                
             Write partition table to disk (this might destroy data)
 

When the program quits, you will get a response that the partition table has changed.

 Disk has been changed.
 
 WARNING: If you have created or modified any
 DOS 6.x partitions, please see the cfdisk manual
 page for additional information.
 

Set up the partition table for the second drive.

 ubuntu ~ # cfdisk /dev/sdb
 

This bring us the same menu-based application, and you do the same to this drive.

                            cfdisk (util-linux 2.20.1)
 
                               Disk Drive: /dev/sdb
                       Size: 1000204886016 bytes, 1000.2 GB
              Heads: 255   Sectors per Track: 63   Cylinders: 121601
 
     Name        Flags      Part Type  FS Type          [Label]        Size (MB)
  ------------------------------------------------------------------------------
     sdb1        Boot        Primary   Linux raid autodetect              131.61 
     sdb2                    Primary   Linux raid autodetect          1000073.29*
 
 
 
 
 
 
 
 
 
 
      [ Bootable ]  [  Delete  ]  [   Help   ]  [ Maximize ]  [  Print   ]
      [   Quit   ]  [   Type   ]  [  Units   ]  [  Write   ]
 
             Write partition table to disk (this might destroy data)
 


Confirtmation that the partition table wrote to the disk.

 Disk has been changed.
 
 WARNING: If you have created or modified any
 DOS 6.x partitions, please see the cfdisk manual
 page for additional information.

=== Validate The Partition Tables ===

 ubuntu ~ # fdisk -l /dev/sda
 
 Disk /dev/sda: 1000.2 GB, 1000204886016 bytes
 255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 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/sda1   *          63      257039      128488+  fd  Linux raid autodetect
 Partition 1 does not start on physical sector boundary.
 /dev/sda2          257040  1953525167   976634064   fd  Linux raid autodetect

 ubuntu ~ # fdisk -l /dev/sdb
 
 Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes
 255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 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   *          63      257039      128488+  fd  Linux raid autodetect
 Partition 1 does not start on physical sector boundary.
 /dev/sdb2          257040  1953525167   976634064   fd  Linux raid autodetect

 ubuntu ~ # cfdisk -P s /dev/sda
 
 Partition Table for /dev/sda
 
                First       Last
  # Type       Sector      Sector   Offset    Length   Filesystem Type (ID) Flag
 -- ------- ----------- ----------- ------ ----------- -------------------- ----
  1 Primary           0      257039     63      257040 Linux raid auto (FD) Boot
  2 Primary      257040  1953525167*     0  1953268128*Linux raid auto (FD) None

 ubuntu ~ # cfdisk -P s /dev/sdb
 
 Partition Table for /dev/sdb
 
                First       Last
  # Type       Sector      Sector   Offset    Length   Filesystem Type (ID) Flag
 -- ------- ----------- ----------- ------ ----------- -------------------- ----
  1 Primary           0      257039     63      257040 Linux raid auto (FD) Boot
  2 Primary      257040  1953525167*     0  1953268128*Linux raid auto (FD) None

=== Create RAID volumes ===

We will delay creating the first RAID array that will be used to house the /boot partition as the Ubuntu installer has issues.

''IGNORE THE NEXT COMMAND''

 ubuntu ~ # mdadm --create /dev/md0 --metadata=0.90 --level=raid1 --raid-devices=2 /dev/sda1 /dev/sdb1
 
 mdadm: array /dev/md0 started.
 

Create the second drive array.  This will house our LVM.

 ubuntu ~ # mdadm --create /dev/md1 --level=raid1 --raid-devices=2 /dev/sda2 /dev/sdb2
 
 mdadm: Note: this array has metadata at the start and
     may not be suitable as a boot device.  If you plan to
     store '/boot' on this device please ensure that
     your boot-loader understands md/v1.x metadata, or use
     --metadata=0.90
 Continue creating array? yes
 mdadm: Defaulting to version 1.2 metadata
 mdadm: array /dev/md1 started.
 

Validate the RAID Array.

 ubuntu ~ # mdadm --detail /dev/md1
 
 /dev/md1:
         Version : 1.2
   Creation Time : Tue Apr 22 23:12:20 2014
      Raid Level : raid1
      Array Size : 976502848 (931.27 GiB 999.94 GB)
   Used Dev Size : 976502848 (931.27 GiB 999.94 GB)
    Raid Devices : 2
   Total Devices : 2
     Persistence : Superblock is persistent
 
     Update Time : Tue Apr 22 23:12:20 2014
           State : clean, resyncing 
  Active Devices : 2
 Working Devices : 2
  Failed Devices : 0
   Spare Devices : 0
 
   Resync Status : 1% complete
 
            Name : ubuntu:1  (local to host ubuntu)
            UUID : 6046228f:32784aeb:8a3c6dc6:0ce79271
          Events : 0
 
     Number   Major   Minor   RaidDevice State
        0       8        2        0      active sync   /dev/sda2
        1       8       18        1      active sync   /dev/sdb2

=== Create lvm volumes ===

Create the physical lvm volume.

 ubuntu ~ # pvcreate /dev/md1
   Physical volume "/dev/md1" successfully created
 

Validate the physical lvm volume.

 ubuntu ~ # pvdisplay 
 
   "/dev/md1" is a new physical volume of "931.27 GiB"
   --- NEW Physical volume ---
   PV Name               /dev/md1
   VG Name               
   PV Size               931.27 GiB
   Allocatable           NO
   PE Size               0   
   Total PE              0
   Free PE               0
   Allocated PE          0
   PV UUID               I7upUe-X1ry-zms2-AlFZ-TVCg-yJcI-CApP5M
 

Create the volume group.

 ubuntu ~ # vgcreate vg1 /dev/md1
   Volume group "vg1" successfully created
 

Validate the volume group.

 ubuntu ~ # vgdisplay 
   --- Volume group ---
   VG Name               vg1
   System ID             
   Format                lvm2
   Metadata Areas        1
   Metadata Sequence No  1
   VG Access             read/write
   VG Status             resizable
   MAX LV                0
   Cur LV                0
   Open LV               0
   Max PV                0
   Cur PV                1
   Act PV                1
   VG Size               931.26 GiB
   PE Size               4.00 MiB
   Total PE              238403
   Alloc PE / Size       0 / 0   
   Free  PE / Size       238403 / 931.26 GiB
   VG UUID               sgvBNE-x48c-QeXm-dV8E-BHAr-Eg9l-aajczw
 

Create the first logical volume.  Leave enough room for your swap volume.

 ubuntu ~ # lvcreate -L 927G vg1 -n lv1
 
   Logical volume "lv1" created
 

Create the swap volume.

 ubuntu ~ # lvcreate -L 4G vg1 -n lv2
 
   Logical volume "lv2" created
 

Validate the new lvm volumes.

 ubuntu ~ # lvdisplay
 
   --- Logical volume ---
   LV Path                /dev/vg1/lv2
   LV Name                lv2
   VG Name                vg1
   LV UUID                1UuUtB-pqxh-NBHl-V2H7-0K6z-5sA6-OeYSl9
   LV Write Access        read/write
   LV Creation host, time ubuntu, 2014-04-22 23:23:55 +0000
   LV Status              available
   # open                 0
   LV Size                4.00 GiB
   Current LE             1024
   Segments               1
   Allocation             inherit
   Read ahead sectors     auto
   - currently set to     256
   Block device           252:0
    
   --- Logical volume ---
   LV Path                /dev/vg1/lv1
   LV Name                lv1
   VG Name                vg1
   LV UUID                MnhRh8-zNAU-G3gl-X4g2-xKsJ-dyfj-7ZH7Ii
   LV Write Access        read/write
   LV Creation host, time ubuntu, 2014-04-22 23:24:21 +0000
   LV Status              available
   # open                 0
   LV Size                927.00 GiB
   Current LE             237312
   Segments               1
   Allocation             inherit
   Read ahead sectors     auto
   - currently set to     256
   Block device           252:1
 

=== Format the Volumes ===

Format the TEMPORARY "/boot" volume.

 ubuntu ~ # mkfs.ext4 /dev/sda1
 
 mke2fs 1.42.8 (20-Jun-2013)
 /dev/sda1 alignment is offset by 512 bytes.
 This may result in very poor performance, (re)-partitioning suggested.
 Filesystem label=
 OS type: Linux
 Block size=1024 (log=0)
 Fragment size=1024 (log=0)
 Stride=4 blocks, Stripe width=4 blocks
 32128 inodes, 128384 blocks
 6419 blocks (5.00%) reserved for the super user
 First data block=1
 Maximum filesystem blocks=67371008
 16 block groups
 8192 blocks per group, 8192 fragments per group
 2008 inodes per group
 Superblock backups stored on blocks:  
 	8193, 24577, 40961, 57345, 73729
 
 Allocating group tables: done                            
 Writing inode tables: done                            
 Creating journal (4096 blocks): done
 Writing superblocks and filesystem accounting information: done 
 

Format the "/" volume.

 ubuntu ~ # mkfs.ext4 /dev/vg1/lv1
 
 mke2fs 1.42.8 (20-Jun-2013)
 Filesystem label=
 OS type: Linux
 Block size=4096 (log=2)
 Fragment size=4096 (log=2)
 Stride=0 blocks, Stripe width=0 blocks
 60751872 inodes, 243007488 blocks
 12150374 blocks (5.00%) reserved for the super user
 First data block=0
 Maximum filesystem blocks=4294967296
 7416 block groups
 32768 blocks per group, 32768 fragments per group
 8192 inodes per group
 Superblock backups stored on blocks:
 	32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208, 
 	4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968, 
 	102400000, 214990848
 
 Allocating group tables: done                            
 Writing inode tables: done                            
 Creating journal (32768 blocks): done
 Writing superblocks and filesystem accounting information: done     
 

Make the swap volume.

 ubuntu ~ # mkswap  /dev/vg1/lv2
 
 mkswap: /dev/vg1/lv2: warning: don't erase bootbits sectors
         on whole disk. Use -f to force.
 Setting up swapspace version 1, size = 4194300 KiB
 no label, UUID=20d4a4a2-f385-4de3-bb42-039153d92c21

== Run installer ==

When asked for partition information, choose "do something else" option, and set up the partition tables there.  Use /dev/vg1/lv1 for the "/" volume, /dev/sda1 as the "/boot" volume, and /dev/vg1/lv2 as the "swap" volume.  Do not use /dev/sdb1 for anything.

Continue the setup, filling out the optional dialogues.

When installation finishes, click "continue testing".

== Create the /dev/md0 RAID for /boot ==

=== Mount the newly created system to /mnt ===

 ubuntu ~ # mount /dev/vg1/lv1 /mnt
 ubuntu ~ # mount /dev/sda1 /mnt/boot

=== Copy the /mnt/boot directory to /mnt/var/tmp/boot.sda1 ===

 ubuntu ~ # cp -pr /mnt/boot /mnt/var/tmp/boot.sda1

=== Unmount /dev/sda1 ===

 ubuntu ~ # umount /mnt/boot

=== Destroy the /dev/sda1 filesystem ===

 ubuntu ~ # shred -v -n 1 /dev/sda1
 
 shred: /dev/sda1: pass 1/1 (random)...

=== Create the /dev/md0 RAID that will house /boot. ===

 ubuntu ~ # mdadm --create /dev/md0 --metadata=1.0 --level=raid1 --raid-devices=2 /dev/sda1 /dev/sdb1
 
 mdadm: array /dev/md0 started.

Validate the RAID Array.

 ubuntu ~ # mdadm --detail /dev/md0
 
 /dev/md0:
         Version : 1.0
   Creation Time : Wed Apr 23 14:55:58 2014
      Raid Level : raid1
      Array Size : 128448 (125.46 MiB 131.53 MB)
   Used Dev Size : 128448 (125.46 MiB 131.53 MB)
    Raid Devices : 2
   Total Devices : 2
     Persistence : Superblock is persistent
 
     Update Time : Wed Apr 23 14:55:58 2014
           State : clean, resyncing (DELAYED) 
  Active Devices : 2
 Working Devices : 2
  Failed Devices : 0
   Spare Devices : 0
 
            Name : ubuntu:0  (local to host ubuntu)
            UUID : cd97e632:b0d6a849:03f97bba:68c49564
          Events : 0
 
     Number   Major   Minor   RaidDevice State
        0       8        1        0      active sync   /dev/sda1
        1       8       17        1      active sync   /dev/sdb1

=== Create new filesystem on /dev/md0 ===

 ubuntu ~ # mkfs.ext4 /dev/md0
 
 mke2fs 1.42.8 (20-Jun-2013)
 /dev/md0 alignment is offset by 512 bytes.
 This may result in very poor performance, (re)-partitioning suggested.
 Filesystem label=
 OS type: Linux
 Block size=1024 (log=0)
 Fragment size=1024 (log=0)
 Stride=4 blocks, Stripe width=4 blocks
 32128 inodes, 128448 blocks
 6422 blocks (5.00%) reserved for the super user
 First data block=1
 Maximum filesystem blocks=67371008
 16 block groups
 8192 blocks per group, 8192 fragments per group
 2008 inodes per group
 Superblock backups stored on blocks: 
 	8193, 24577, 40961, 57345, 73729
 
 Allocating group tables: done                            
 Writing inode tables: done                            
 Creating journal (4096 blocks): done
 Writing superblocks and filesystem accounting information: done 

=== Mount new /boot partition ===

 ubuntu ~ # mount /dev/md0 /mnt/boot

=== Copy /mnt/var/tmp/boot.sda1 /mnt/boot ===

 ubuntu ~ # cp -pr /mnt/var/tmp/boot.sda1/* /mnt/boot/

== Copy important bit over to the destination ==

 ubuntu / # mount -o bind /dev /mnt/dev/
 
 ubuntu / # mount -o bind /dev/pts /mnt/dev/pts
 
 ubuntu / # mount -o bind /proc /mnt/proc
 
 ubuntu / # mount -o bind /sys /mnt/sys
 
 ubuntu / # cp /etc/resolv.conf /mnt/etc/

== CHROOT into the new installation to install mdadm and grub ==

=== CHROOT ===

Execure the chroot command

 ubuntu / # chroot /mnt
 

=== Install mdadm in the destination system ===

 ubuntu grub # apt-get install mdadm
 
 Reading package lists... Done
 Building dependency tree       
 Reading state information... Done
 Recommended packages:
   default-mta mail-transport-agent
 The following NEW packages will be installed:
   mdadm
 0 upgraded, 1 newly installed, 0 to remove and 265 not upgraded.
 Need to get 520 kB of archives.
 After this operation, 1,190 kB of additional disk space will be used.
 Get:1 http://archive.ubuntu.com/ubuntu/ saucy/main mdadm amd64 3.2.5-5ubuntu2 [520 kB]
 Fetched 520 kB in 6s (81.6 KB/s)
 Preconfiguring packages ...
 Selecting previously unselected package mdadm.
 (Reading database ... 164540 files and directories currently installed.)
 Unpacking mdadm (from .../mdadm_3.2.5-5ubuntu2_amd64.deb) ...
 Processing triggers for ureadahead ...
 Processing triggers for man-db ...
 Processing triggers for doc-base ...
 Processing 6 added doc-base files...
 Registering documents with scrollkeeper...
 Setting up mdadm (3.2.5-5ubuntu2) ...
 Generating mdadm.conf... done.
  Removing any system startup links for /etc/init.d/mdadm-raid ...
 update-initramfs: deferring update (trigger activated)
  * Starting MD monitoring service mdadm --monitor                          [ OK ] 
 Processing triggers for ureadahead ...
 Processing triggers for initramfs-tools ...
 update-initramfs: Generating /boot/initrd.img-3.11.0-12-generic
 Warning: No support for locale: en_US.utf8
 

mdadm installation may fail, however you may be able to manually install it.

 ubuntu / # cd /root/
 
 ubuntu ~ # wget http://launchpadlibrarian.net/135397377/mdadm_3.2.5-5ubuntu2_amd64.deb
 
 --2014-04-22 19:12:33--  http://launchpadlibrarian.net/135397377/mdadm_3.2.5-5ubuntu2_amd64.deb
 Resolving launchpadlibrarian.net (launchpadlibrarian.net)... 91.189.89.229, 91.189.89.228
 Connecting to launchpadlibrarian.net (launchpadlibrarian.net)|91.189.89.229|:80... connected.
 HTTP request sent, awaiting response... 200 OK
 Length: 519554 (507K) [application/x-debian-package]
 Saving to: ‘mdadm_3.2.5-5ubuntu2_amd64.deb’
 
 100%[======================================>] 519,554      462KB/s   in 1.1s   
 
 2014-04-22 19:12:40 (462 KB/s) - ‘mdadm_3.2.5-5ubuntu2_amd64.deb’ saved [519554/519554]
 
 ubuntu / # dpkg -i mdadm_3.2.5-5ubuntu2_amd64.deb
 
 Selecting previously unselected package mdadm.
 (Reading database ... 162748 files and directories currently installed.)
 Unpacking mdadm (from mdadm_3.2.5-5ubuntu2_amd64.deb) ...
 Setting up mdadm (3.2.5-5ubuntu2) ...
 Generating mdadm.conf... done.
  Removing any system startup links for /etc/init.d/mdadm-raid ...
 update-initramfs: deferring update (trigger activated)
  * Starting MD monitoring service mdadm --monitor                        [ OK ] 
 Processing triggers for ureadahead ...
 Processing triggers for man-db ...
 Processing triggers for doc-base ...
 Processing 6 added doc-base files...
 Registering documents with scrollkeeper...
 Processing triggers for initramfs-tools ...
 update-initramfs: Generating /boot/initrd.img-3.11.0-12-generic
 Warning: No support for locale: en_US.utf8

=== Validate /etc/mdadm/mdadmn.conf file ===

 ubuntu ~ # /usr/share/mdadm/mkconf > /tmp/mdadm.conf
 ubuntu ~ # diff /tmp/mdadm.conf /etc/mdadm/mdadm.conf
 
 21d20
 < ARRAY /dev/md0 UUID=cd97e632:b0d6a849:03f97bba:68c49564
 23a23,24
 > # This file was auto-generated on Tue, 22 Apr 2014 19:13:40 -0600
 > # by mkconf $Id$

Make changes, as needed.

=== Run grub-mkconfig ===

 ubuntu ~ # mv /boot/grub/grub.{cfg,bak}

 ubuntu ~ # /usr/sbin/grub-mkconfig > /boot/grub/grub.cfg

=== Install Grub ===

Install on /dev/sda

 ubuntu ~ # grub-install.real /dev/sda
 
 Installation finished. No error reported.

Install on /dev/sdb

 ubuntu ~ # grub-install.real /dev/sdb
 
 Installation finished. No error reported.

=== Update /etc/fstab ===

You will need to update the /boot directory for the fstab, or you will not mount at boot time.  This can be done easily after installation and reboot.