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--- administration:system-mirror [2008/03/12 18:40] – damir
+++ administration:system-mirror [2009/03/16 14:00] (current) – damir
@@ Line 1: / Line 1: @@
 ====== Mini Raid Software howto ======
-==== Prologue ====
+===== Prologue =====
-  * with the instructions that follow we move a complete root system disk from bare partitions to a raid 1 software layer.
+  * with the instructions that follow we move a complete root system disk from bare partitions to a RAID 1 software layer.
-  * all the work is done without putting the server off-line.
+  * obviously you can use the same trick to upgrade to a RAID 5 software system
-  * only one reboot process is needed if the disks are already installed on the server.
+  * **all the work is done without putting the server off-line, but it's better to stop the services before starting the copy of the files from the old disk to the new one**
+  * only one reboot process is needed if the disks are already installed on the server and if the whole process is correct.
+==== The second disk is already installed and the partition Table is empty ====
-==== Preparing the system ====
+ **else remove the partitions on the second disk by hand pbefore starting this procedure**
-We will move the system disk of a linux system from a standard partition scheme, to a raid 1 system withous
-=== We suppose that the second disk is already installed and that the partition Table is empty ===
   * /dev/sda: is the original disk from where the system boot
   * /dev/sdb: is the second disk
-\\
-  * we need to create the correct partitions we need:
+==== create the correct partitions we need ====
     * 100 MB for the boot partition
     * 2Gbyte for the swap partition (there's no need to put the swap partitions on a raid system)
@@ Line 48: / Line 48: @@
-  * now we need to create the raid 1 partitions for the boot and the other partitions
+==== now we need to create the raid 1 partitions for the boot and the other partitions ====
   * /dev/md0 will be the first raid 1 partition used only by the /boot directory
   * /dev/md1 will be the raid 1 disk used for everything else
@@ Line 55: / Line 55: @@
  mdadm --create /dev/md0 --level=1 --raid-devices=2 missing /dev/sdb1
  mdadm --create /dev/md1 --level=1 --raid-devices=2 missing /dev/sdb3
+ echo 'DEVICE /dev/hd*[0-9] /dev/sd*[0-9]' > /etc/mdadm.conf
+ mdadm --detail --scan >> /etc/mdadm.conf
+</code>
+  * we created the raid devices (in downgraded mode)
+  * the informations about the devices is written in the **/etc/mdadm.conf** file.
+==== the /dev/md0 partition will be used flat for the boot partitions ====
+  * so we can format it right now
+<code>
+  mkfs.ext3 /dev/md0
+</code>
+==== the /dev/md1 partition will be splitted using the lvm layer ====
+  * if the virtual disk **vg1** is already used, please change the example below
+<code>
+  pvcreate /dev/md1
+  vgcreate vg1 /dev/md1
+  lvcreate --name root -L 4G vg1
+  lvcreate --name usrlocal -L 4G vg1
+  lvcreate --name var -L 4G vg1
+  lvcreate --name export -L <bigger than the disk>G vg1
+  lvcreate --name export -l <extens available reported by the previous command> vg1
+</code>
+  * we assigned the /dev/md1 partition to an lvm disk and we created different lvm partitions
+  * now we need to format the partitions just created
+<code>
+  mkfs.ext3 /dev/vg1/root
+  mkfs.ext3 /dev/vg1/usr/local
+  mkfs.ext3 /dev/vg1/var
+  mkfs.ext3 /dev/vg1/export
+</code>
+==== time to mount the partitions to copy the system from the original disk ====
+<code>
+  mkdir /1
+  mount /dev/vg1/root /1
+  cd /1
+  mkdir -p boor usr/local var export proc sys dev
+  mount /dev/md0 boot
+  mount /dev/vg1/usrlocal usr/local
+  mount /dev/vg1/var var
+  mount /dev/vg1/export export
+</code>
+  * ok, the new partitions are mounted and ready to receive all the contents
+<code>
+  rsync -aH --exclude=/1 --exclude=/proc --exclude=/sys --exclude=/dev / /1/
+</code>
+  * wait until the system is copied
+==== Create the new initrd image file ====
+  * after the copy we need to create a new initrd and change the information in the **/1/etc/fstab** file
+  * avoid the use of label inside this file, instead use the physical name of the devices
+  * you should have something like that:
+<code>
+vi /1/etc/fstab
+/dev/vg1/root           /                       ext3    defaults        1 1
+/dev/md0                /boot                   ext3    defaults        1 2
+tmpfs                   /dev/shm                tmpfs   defaults        0 0
+devpts                  /dev/pts                devpts  gid=5,mode=620  0 0
+sysfs                   /sys                    sysfs   defaults        0 0
+proc                    /proc                   proc    defaults        0 0
+/dev/vg1/export         /export                 ext3    defaults        1 2
+/dev/vg1/var            /var                    ext3    defaults        1 2
+/dev/vg1/usrlocal       /usr/local              ext3    defaults        1 2
+#LABEL=SWAP-sda2         swap                    swap    defaults        0 0
+LABEL=SWAP-sdb2         swap                    swap    defaults        0 0
+</code>
+  * the reference to the swap partition on the first disk must be commented
+  * now we can create the new initrd image **include also the serial-ata module, if necessary**
+<code>
+mkinitrd --preload raid1 --preload raid456 --preload sata_nv --fstab /1/etc/fstab /boot/initrd-$(uname -r)-raid.img $(uname -r)
+</code>
+==== Edit the grub configuration file in the original disk ====
+  * change the file adding a instance forthe new disk
+  * this is the original instance:
+<code>
+title Fedora (2.6.23.15-80.fc7) RAID
+        root (hd0,0)
+        kernel /vmlinuz-2.6.23.15-80.fc7 ro root=/dev/vg1/root vga=791 selinux=0 noipv6 panic=30
+        initrd /initrd-2.6.23.15-80.fc7.img
+</code>
+  * must be changed in:
+<code>
+title Fedora (2.6.23.15-80.fc7) RAID
+        root (hd0,0)
+        kernel /vmlinuz-2.6.23.15-80.fc7 ro root=/dev/vg1/root vga=791 selinux=0 noipv6 panic=30
+        initrd /initrd-2.6.23.15-80.fc7-2.img
+title Fedora (2.6.23.15-80.fc7) RAID
+        root (hd1,0)
+        kernel /vmlinuz-2.6.23.15-80.fc7 ro root=/dev/vg1/root vga=791 selinux=0 noipv6 panic=30
+        initrd /initrd-2.6.23.15-80.fc7-2-raid.img
+</code>
+  * leave the default boot partition to the old disk, so in case of trouble we can reboot
+==== Install the boot loader on the second disk ====
+  * we need to install the grub boot loader on the new disk using the **grub** command
+  * avoid the **grub-install** command, doesn't work for complex situation like this
+<code>
+  grub
+  root (hd1,0) [enter]
+  setup (hd1) [enter]
+  quit [enter]
+</code>
+==== update the data on the second disk ====
+ * we need to copy the changes from the original disk to the new one
+<code>
+  rsync -aH /boot/ /1/boot/
+</code>
+==== Reboot ====
+  * time to reboot and see what happens
+<code>
+  reboot
+</code>
+  * **at the boot prompt select the second boot option** and verify that is the right one checking that contains the **root (hd1,0)** line
+  * if everything was right the system should boot with the raid 1 disk
+===== The New System =====
+  * now we have the system running on the software raid disk, but the raid is in downgrade mode (only one disk is operating at the moment)
+  * we need to connect the original disk tho the current one
+  * for this reason we need to remove all the partitions on the old disk a recreate the new partition map that must be identical to the one of the **/dev/sdb** disk we are using now.
+  * in our examples /dev/vg0 is the old lvm disk
+==== Deleting the old lvm partitions ====
+  * we disable the old lvm partitions to avoid confusion
+<code>
+ lvchange -a n vg0/root
+ lvchange -a n vg0/usrlocal
+ lvchange -a n vg0/var
+ lvchange -a n vg0/export
+</code>
+  * now we can erase the lvm partitions
+<code>
+  lvremove vg0/root
+  lvremove vg0/usrlocal
+  lvremove vg0/var
+  lvremove vg0/export
+</code>
+  * then we need to remove the vg
+<code>
+  vgremove vg0
+  pvremove /dev/sda3
+</code>
+==== Creating the new partition table form the second disk ====
+ * now we can recreate the new partition table copying the partition of /dev/sdb to /dev/sda
+<code>
+ sfdisk -d /dev/sdb | sfdisk /dev/sda
+</code>
+==== add the second disk to the raid system ..... ====
+<code>
+  mdadm --manage /dev/md0 --add /dev/sda1
+  mdadm --manage /dev/md1 --add /dev/sda3
+</code>
+  * the raid subsystem is synchronizing the content of both disks
+==== .... and update the grub code ====
+<code>
+  grub
+  root (hd0,0)
+  setup (hd0)
+  quit
+</code>
+==== the last task is to create the second swap partition ====
+<code>
+  mkswap -L SWAP-sda2 /dev/sda2
+  swapon /dev/sda2
+</code>
+  * uncomment the line about the swap partition inside /etc/fstab
+===== Kernel upgrade =====
+**During Kernel upgrade the grub file must be manually modified in order to add the reference to the second disk**