Changes

It should tell you there if the drives are syncing up. Don't turn off the server until the sync is complete or it will start from the beginning again. When it is done syncing it will show a good working raid1.

It should tell you there if the drives are syncing up. Don't turn off the server until the sync is complete or it will start from the beginning again. When it is done syncing it will show a good working raid1.

If the Manage disk redundancy page gives the message "The free disk count must equal one" and "Manual intervention may be required", then you likely will have additional hard drives that need to be disconnected while the RAID is set up. An external USB drive will have this effect, and should be unplugged.

If the Manage disk redundancy page gives the message "The free disk count must equal one" and "Manual intervention may be required", then you probably have additional hard drives that need to be disconnected while the RAID is set up. An external USB drive will have this effect, and should be unplugged.

{{Note box| the addition of another drive is restricted to a RAID 1 degraded, i.e. when the system has been installed with a single drive (/dev/hda and /dev/hdc or their SATA equivalent). The addition of a third drive to a RAID 1 '''(i.e. a spare)''' is not recognized by the system. therefore you need to use the '''mdadm''' command line}}

{{Note box| the addition of another drive is restricted to a RAID 1 degraded, i.e. when the system has been installed with a single drive (/dev/hda and /dev/hdc or their SATA equivalent). The addition of a third drive to a RAID 1 '''(i.e. a spare)''' is not recognized by the system. To add a spare you need to use '''mdadm''' at the command line}}

{{Note box|I suppose the system is installed with a Raid1 functional on two disk sda and sdb and you want to add another disk sdc as a spare (for use automatically if one disk of the array will fail).This howto can be adapted to other types of Raid as long as you want to add a spare disk.}}

{{Note box|I will assume the system is installed with a RAID 1 array functioning on two disks sda and sdb and you want to add another disk sdc as a spare (for use automatically if one disk of the array will fail). This howto can be adapted to other types of RAID as long as you want to add a spare disk.}}

first we need to give to sdc the same table of partition as sda or sdb

First we need write the partition table from  sda (or sdb) to sdc :

  sfdisk /dev/sdc < sfdisk_sda.output

  sfdisk /dev/sdc < sfdisk_sda.output

then we need to add the news partitions to the existings arrays

Then we need to add the new partitions to the existings arrays :

  mdadm --add /dev/md1 /dev/sdc1

  mdadm --add /dev/md1 /dev/sdc1

  mdadm --add /dev/md2 /dev/sdc2

  mdadm --add /dev/md2 /dev/sdc2

  mdadm --detail /dev/md1

  mdadm --detail /dev/md1

         2      8      33        -      spare  /dev/sdc1

         2      8      33        -      spare  /dev/sdc1

else you can try this.

Alternatively you can try this.

  cat /proc/mdstat

  cat /proc/mdstat

[0]= number of the disk

[0]= number of the disk

you might be interested to install grub on your spare disk for securing the boot process.

You should ensure that grub is correctly written to spare disk to ensure it will boot correctly.

in a terminal with the  administrator privilege.

From within a terminal with the  administrator privileges :

  grub

  grub

  root (hd2,0)

  root (hd2,0)

  setup (hd2)

  setup (hd2)