Switching to RAID 1 for XenServer 6.1 with GPT

Instructions for switching to RAID 1 for XenServer 6.1 with GPT
---------------------------------------------------------------

Check /dev/sda partition table
# gdisk -l /dev/sda
(...)
Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048         8388641   4.0 GiB     0700
   2         8390656        16777249   4.0 GiB     0700
   3        16779264      1953525134   923.5 GiB   8E00


Check /dev/sdb partition table
# gdisk -l /dev/sdb


Create RAID partitions on /dev/sdb
# gdisk /dev/sdb


Replicate the partition table sectors. Choose fd00 as code for partition type.

The result should look something like this:
Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048         8388641   4.0 GiB     FD00  Linux RAID
   2         8390656        16777249   4.0 GiB     FD00  Linux RAID
   3        16779264      1953525134   923.5 GiB   FD00  Linux RAID


Create MD devices
# mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sdb1 missing
# mdadm --create /dev/md1 --level=1 --raid-devices=2 /dev/sdb2 missing
# mdadm --create /dev/md2 --level=1 --raid-devices=2 /dev/sdb3 missing


Copy Store Manager Data to RAID
# pvcreate /dev/md2
# vgextend VG_<TAB> /dev/md2
# pvmove /dev/sda3 /dev/md2


Remove /dev/sda3 from the SR volume group
# vgreduce VG_<TAB> /dev/sda3
# pvremove /dev/sda3


Mount /dev/md0 and copy the filesystem to it
# mkfs.ext3 /dev/md0
# mount /dev/md0 /mnt
# cd /
# cp -axv . /mnt


Modify /mnt/etc/fstab and change the root= parameter to /dev/md0. (Do NOT include the LABEL=)


Create a new boot image and uncompress it:
# mkdir /mnt/root/initrd-raid
# mkinitrd -v --fstab=/mnt/etc/fstab /mnt/root/initrd-raid/initrd-`uname -r`-raid.img `uname -r`
# cd /mnt/root/initrd-raid
# zcat initrd-`uname -r`-raid.img | cpio -i


Edit 'init' and insert the below test after 'raidautorun /dev/md0':
raidautorun /dev/md1
raidautorun /dev/md2


Copy the new ramdisk to the /mnt/boot folder and modify boot menu
# find . -print | cpio -o -Hnewc | gzip -c > /mnt/boot/initrd-`uname -r`-raid.img
# rm /mnt/boot/initrd-2.6-xen.img
rm: remove symbolic link `/mnt/boot/initrd-2.6-xen.img’? y
# ln -s initrd-`uname -r`-raid.img /mnt/boot/initrd-2.6-xen.img
# vi /mnt/boot/extlinux.conf
Replace "root=LABEL=root-xyz" by "root=/dev/md0" in all menu entries.


Set up MBR for GPT on /dev/sdb
# cat /mnt/usr/share/syslinux/gptmbr.bin > /dev/sdb
# cd /mnt
# extlinux  --raid -i boot/


Unmount /dev/md0
# cd
# umount /dev/md0
# sync


Make sure the bootable flag is set on the partitions
# sgdisk /dev/sda --attributes=1:set:2
# sgdisk /dev/sdb --attributes=1:set:2


Reboot (IMPORTANT: Set your server to boot from the SECONDARY HDD before booting!)
# reboot


After the reboot is (hopefully) complete, it's time to switch /dev/sda's partitions to RAID
# gdisk /dev/sda
Press 't' select partition number and type in fd00.
Repeat for all your partitions. Then 'w' to write changes.
Your partition table should look something like this:

(...)
Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048         8388641   4.0 GiB     FD00
   2         8390656        16777249   4.0 GiB     FD00
   3        16779264      1953525134   923.5 GiB   FD00


You are now ready to add these partitions into the RAID arrays
# mdadm -a /dev/md0 /dev/sda1
mdadm: added /dev/sda1
# mdadm -a /dev/md1 /dev/sda2
mdadm: added /dev/sda2
# mdadm -a /dev/md2 /dev/sda3
mdadm: added /dev/sda3


To check how the RAID sync is going look at:
# cat /proc/mdstat


When it's done on all three arrays, copy the RAID setup to /etc/mdadm.conf
# mdadm --detail --scan >> /etc/mdadm.conf

Finally restore the Volume Group
# cd /etc/lvm/backup
# vgcfgrestore --file VG_<TAB> VG_<TAB>

You should now have a fully functional RAID 1 XenServer 6.1 Setup!