Simple definition
Linux software RAID combines disks into resilient or higher-performance arrays using kernel-managed components such as md.
Purpose and use
Linux software RAID combines devices into an array whose capacity and fault tolerance depend on the selected RAID level.
How does it work?
The MD subsystem manages members and rebuild operations for supported configurations.
Example and verification
After an incident, inspect array state, individual devices and rebuild progress.
Points to watch
Redundancy does not protect against logical deletion, propagated corruption or every disaster. RAID 0 provides no redundancy.
In short
RAID supplies selected storage properties rather than a replacement for recoverable backups.