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Device mapper
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<p>The device mapper is a <a href="/facts/Software_framework/EWasA8sG">framework</a> provided by the <a href="/facts/Linux_kernel/dlkduHuA">Linux kernel</a> for mapping physical <a href="/facts/Block_device/t8ISnXft">block devices</a> onto higher-level <i>virtual block devices</i>. It forms the foundation of the <a href="/facts/Logical_volume_manager/ku3Ivefk">logical volume manager</a> (LVM), software <a href="/facts/RAID/IpzWWgog">RAIDs</a> and <a href="/facts/Dm-crypt/DpsfvyrW">dm-crypt</a> disk encryption, and offers additional features such as file system <a href="/facts/Snapshot_(computer_storage)/LKm3NX2A">snapshots</a>. </p><p>Device mapper works by passing data from a virtual block device, which is provided by the device mapper itself, to another block device. Data can be also modified in transition, which is performed, for example, in the case of device mapper providing <a href="/facts/Disk_encryption/v7E50jGw">disk encryption</a> or simulation of unreliable hardware behavior. </p><p>This article focuses on the device mapper implementation in the Linux kernel, but the device mapper functionality is also available in both <a href="/facts/NetBSD/PTm5HWls">NetBSD</a> and <a href="/facts/DragonFly_BSD/U6cvpDJR">DragonFly BSD</a>. </p>