6.3.4. Extending a RAID Device
To add a new device to an existing array, use the command in the following form as
root:
mdadmraid_device--addcomponent_device
This will add the device as a spare device. To grow the array to use this device actively, type the following at a shell prompt:
mdadm--growraid_device--raid-devices=number
Example 6.4. Extending a RAID device
Assume the system has an active RAID device,
/dev/md3, with the following layout (that is, the RAID device created in Example 6.2, “Creating a new RAID device”):
~]# mdadm --detail /dev/md3 | tail -n 3
Number Major Minor RaidDevice State
0 8 1 0 active sync /dev/sda1
1 8 17 1 active sync /dev/sdb1
Also assume that a new SCSI disk drive,
/dev/sdc, has been added and has exactly one partition. To add it to the /dev/md3 array, type the following at a shell prompt:
~]# mdadm /dev/md3 --add /dev/sdc1
mdadm: added /dev/sdc1
This will add
/dev/sdc1 as a spare device. To change the size of the array to actually use it, type:
~]# mdadm --grow /dev/md3 --raid-devices=3