Snapshot target (EXPERIMENTAL)

modulename: dm-snapshot.ko

configname: CONFIG_DM_SNAPSHOT

Linux Kernel Configuration
└─>Device Drivers
└─>Multi-device support (RAID and LVM)
└─>Snapshot target (EXPERIMENTAL)
In linux kernel since version 2.6.20 (release Date: 2007-02-04)  
Allow volume managers to take writable snapshots of a device.

source code:
selects

CONFIG_DM_BUFIO

depends
CONFIG_BLK_DEV_DM
CONFIG_BLOCK
CONFIG_EXPERIMENTAL or CONFIG_MD