Package mdadm

The mdadm program controls Linux md devices (software RAID arrays)

http://www.kernel.org/pub/linux/utils/raid/mdadm/

The mdadm program is used to create, manage, and monitor Linux MD (software
RAID) devices. As such, it provides similar functionality to the raidtools
package. However, mdadm is a single program, and it can perform
almost all functions without a configuration file, though a configuration
file can be used to help with some common tasks.

Special Files (Section 4)
md
The md driver provides virtual devices that are created from one or more independent underlying devices. This array of devices often contains redundancy and the...
File Formats (Section 5)
mdadm.conf
mdadm is a tool for creating, managing, and monitoring RAID devices using the md driver in Linux. Some common tasks, such as assembling all arrays, can be...
System Administration (Section 8)
mdadm
RAID devices are virtual devices created from two or more real block devices. This allows multiple devices (typically disk drives or partitions thereof) to be...
mdmon
Metadata updates To service metadata update requests a daemon, mdmon, is introduced. Mdmon is tasked with polling the sysfs namespace looking for changes in...