The Device Mapper

• The Device Mapper driver provides a generic way of creating mapped devices, which may be logical volumes.

• It has no concept of volume groups.

• It does not know about metadata formats. (Applications can do this in separate kernel code and use the Device Mapper to set up the actual devices.)

• The core driver is only about 2000 lines of code.

• The userland interface is either via ioctl() or via its own filesystem (dmfs).