Device mapper

From Wikipedia, the free encyclopedia

In the Linux kernel, the Device-mapper is a generic framework to map one block device into another. It forms the foundation of LVM2 and EVMS, software RAIDs, Cryptoloop file system encryption, and offers additional features such as file system snapshots.

Device-mapper works by processing data passed in from a virtual block device, that it itself provides, and then passing it on to another block device.

Applications (like LVM2 and EVMS) that want to create new mapped devices talk to the Device-mapper via the libdevmapper.so shared library, which in turn issues ioctls to the /dev/mapper/control device node. Device-mapper is also accessible from shell scripts via the dmsetup tool.

[edit] External links

• Device-mapper Resource Page
• Device mapper home at Red Hat
• Right To Your Own Devices. Linux Gazette (2005-05). - an article that illustrates the use of various Device-mapper targets