Changes

{{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| 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 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.}}

{{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 operates with RAID 1/5/6 as long as you want to add a spare disk.}}

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

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