mdadm raid check

Personalities : [raid1]
md1 : active raid1 sda2[0] sdb2[1]
1952881408 blocks super 1.2 [2/2] [UU]

md0 : active raid1 sda1[0] sdb1[1]
499712 blocks super 1.2 [2/2] [UU]

unused devices: <none>

Personalities : [raid1]
md1 : active raid1 sda2[0] sdb2[1]
1952881408 blocks super 1.2 [2/2] [UU]
[==>………………]  check = 12.4% (244056192/1952881408) finish=3670.1min speed=7744K/sec

md0 : active raid1 sda1[0] sdb1[1]
499712 blocks super 1.2 [2/2] [UU]

unused devices: <none>

checkarray — MD array (RAID) redundancy checker tool
Copyright © martin f. krafft <madduck@debian.org>
Released under the terms of the Artistic Licence 2.0

Usage: checkarray [options] [arrays]

Valid options are:
-a|–all       check all assembled arrays (ignores arrays in command line).
-s|–status    print redundancy check status of devices.
-x|–cancel    queue a request to cancel a running redundancy check.
-i|–idle      perform check in a lowest scheduling class (idle)
-l|–slow      perform check in a lower-than-standard scheduling class
-f|–fast      perform check in higher-than-standard scheduling class
–realtime     perform check in real-time scheduling class (DANGEROUS!)
-c|–cron      honour AUTOCHECK setting in /etc/default/mdadm.
-q|–quiet     suppress informational messages
(use twice to suppress error messages too).
-h|–help      show this output.
-V|–version   show version information.

Examples:
checkarray –all –idle
checkarray –quiet /dev/md[123]
checkarray -sa
checkarray -x –all

Devices can be specified in almost any format. The following are equivalent:
/dev/md0, md0, /dev/md/0, /sys/block/md0

You can also control the status of a check with /proc/mdstat file.