MDRAID Common Commands

Creating an array

# mdadm --create --verbose /dev/md0 --level=1 --ind-devices = 2 /dev/sda1  /dev/sdb1

Then you need to create a configuration file mdadm.conf

# mdadm --detail --scan> /etc/mdadm/mdadm.conf

And write the changes to the boot image:

# update-initramfs -u

Work with array

Mark a disk as failed

The disk in the array can be conditionally failed, the key –fail (-f):

# mdadm /dev/md0 --fail /dev/sda1
# mdadm /dev/md0 -f /dev/sda1

Remove a failed disk

The failed disk can be removed with the –remove (-r) switch:

# mdadm /dev/md0 --remove /dev/sda1
# mdadm /dev/md0 -r /dev/sda1

Adding a new drive

You can add a new disk to the array using the –add (-a) and –re-add options:

# mdadm /dev/md0 --add /dev/sda1
# mdadm /dev/md0 -a /dev/sda1

Build an existing array

You can assemble an existing array using mdadm –assemble. As an additional argument, it is indicated whether the device should be scanned, and if not, which devices should be collected.

# mdadm --assemble /dev/md0 /dev/sda1 /dev/sdb1 /dev/sdc1
# mdadm --assemble --scan

Check array status and get information and array

Array Status:

# cat /proc/mdstat

Array Information:

# mdadm --detail /dev/md0

Information about the array element:

# mdadm --examine /dev/sda1

Integrity check

We oversaw the check

# echo check > /sys/block/md1/md/sync_action

see the result

# cat /proc/mdstat
Personalities: [raid10] [raid1]
md0: active raid1 sdb1 [1] sda1 [0] sdc1 [2] sdd1 [3]
128384 blocks [4/4] [UUUU]

md1: active raid10 sdd2 [3] sdc2 [2] sda2 [0] sdb2 [1]
134222848 blocks 256K chunks 2 near-copies [4/4] [UUUU]
[> ....................] check = 0.5% (787072/134222848) finish = 19.7min speed = 112440K / sec

Kill array

# mdadm --stop  /dev/md0
# mdadm --zero-superblock /dev/sda ..