Topic: Extend existing raid1 with 2x80GB raid 1

[warren]

I was testing the idea of extending the raid1 array ( and therefore the storage ) on a sme9_64;
The initial idea came from the post Nicola made for sme8 ( http://forums.contribs.org/index.php/topic,50996.msg257831.html#msg257831  THANKS.

These are the rough notes here ( so I dont forget / lose them ? );

Install your new hdds (2 existing drives - add 2 new drives - /dev/sdc - /dev/sdd). Start with partitioning:

# fdisk /dev/sdc

n (to add a new partition)
p (to make a primary partition)
1 (that's the number one, the number you want to assign to the partition)
   Only if you will be adding this disk to to a RAID set, then you will also need to change the partition type.
t (to change partition type)
L (within t's prompt to list available partition type)
fd (normally the partition type is fd but verify from the L command and look for "Linux raid autodetect"
   Accept the suggested first & last cylinder values
w (write and exit)
Repeat the same with /dev/sdd:

# fdisk /dev/sdd

Create a new array (say md2):

# mdadm --create  /dev/md2 --level=1 --raid-devices=2 /dev/sdc1 /dev/sdd1

Wait for Raid Array rebuild.

Create Physical Extent for LVM :

# pvcreate /dev/md2

Resize the LVM:

# vgextend main /dev/md2
# lvresize -l +100%FREE  /dev/main/root
# resize2fs  /dev/main/root

Launch pvdisplay to check the result:

--- Physical volume ---
  PV Name               /dev/md1
  VG Name               main
  PV Size               74.22 GiB / not usable 2.88 MiB
  Allocatable           yes (but full)
  PE Size               4.00 MiB
  Total PE              19000
  Free PE               0
  Allocated PE          19000
  PV UUID               gaeEeu-FMUO-CsmF-fXvZ-1Ra5-fP0p-7czCQP

  --- Physical volume ---
  PV Name               /dev/md2
  VG Name               main
  PV Size               74.47 GiB / not usable 3.00 MiB
  Allocatable           yes (but full)
  PE Size               4.00 MiB
  Total PE              19063
  Free PE               0
  Allocated PE          19063
  PV UUID               b65NFX-Kber-Xvbw-eQWQ-bDGq-NL0L-MN61f1

Detect /dev/md2 :

# mdadm --detail /dev/md2 | grep -i uuid
# UUID : fbc206ee:1e056a83:a5fc5f04:b4319c6e

# mdadm --detail /dev/md2 | grep -i uuid >> /etc/mdadm.conf   ( this shows the UUID number (fbc206ee:1e056a83:a5fc5f04:b4319c6e
 )needed in the mdadm.conf file )

Edit mdadm.conf file

Add the "Array /dev/md2 level=raid1 num-devices=2 uuid=( put in the uuid from above )
# nano  /etc/mdadm.conf
# mdadm.conf written out by anaconda
MAILADDR root
AUTO +imsm +1.x -all
ARRAY /dev/md0 level=raid1 num-devices=2 UUID=fc0bb621:773363c6:4320223d:6827133b
ARRAY /dev/md1 level=raid1 num-devices=2 UUID=4d77fd8b:da09b2db:b3c3272c:5f3a039a
ARRAY /dev/md2 level=raid1 num-devices=2 UUID=fbc206ee:1e056a83:a5fc5f04:b4319c6e


Save the file :

Rebuilding the initramfs (RHEL 6) :

Create copy of initramfs first :
# cp /boot/initramfs-$(uname -r).img /boot/initramfs-$(uname -r).img.bak

Creat new initramfs :
# dracut -f -v

Modify /boot/grub.conf to use the new image :

# cd /boot/grub
# nano grub.conf

look for the part of the file "rd_MD_UUID=4d77fd8b:da09b2db:b3c3272c:5f3a039a "

Add a space straight after the section above  ;
Add the following : rd_MD_UUID=fbc206ee:1e056a83:a5fc5f04:b4319c6e

Save file:

Reboot