metadevice

A metadevice is a concept in computing that refers to a virtual device or an abstraction layer that manages and aggregates multiple underlying physical devices. Instead of interacting directly with individual hardware components, an operating system or application interacts with the metadevice, which then handles the distribution of requests and management of the constituent physical devices. This abstraction simplifies device management, allowing for more flexible and efficient use of resources.

The primary purpose of a metadevice is to provide a unified interface. For instance, a RAID (Redundant Array of Independent Disks) controller creates a metadevice that appears as a single large disk to the operating system, even though it is composed of several physical hard drives. The RAID controller then manages data distribution, mirroring, or striping across these physical drives for performance or redundancy. Similarly, software RAID implementations achieve the same goal without dedicated hardware.

Another common application is in storage virtualization, where storage arrays present a logical LUN (Logical Unit Number) as a metadevice to servers, masking the complexities of the underlying physical storage infrastructure. This allows for features like thin provisioning, snapshots, and replication to be managed at the metadevice level. In networking, bonding or teaming multiple network interface cards (NICs) creates a metadevice that offers increased bandwidth and fault tolerance. The metadevice acts as a single network interface, with the underlying NICs managed by the bonding driver.