It is a command using which we can do low level logical volume management. So basically dmsetup is used to manage logical devices that use the device-mapper driver. The first argument to dmsetup is a command. The second argument is the logical device name or uuid.
The package which provides dmsetup command can be found out using:
# yum whatprovices /sbin/dmsetup ... 7:device-mapper-1.02.158-2.el7_7.2.x86_64 : Device mapper utility Repo : @updates Matched from: Filename : /sbin/dmsetup
Examples of using dmsetup command
1. To list the device mapper devices:
# dmsetup ls # dmsetup ls VG00-LV02 (253, 2) VG00-LV01 (253, 1) VG00-LV00 (253, 0)
2. To get information about any DM device:
# dmsetup info /dev/VG00/LV00 # dmsetup info /dev/VG00/LV00 Name: VG00-LV00 State: ACTIVE Read Ahead: 256 Tables present: LIVE Open count: 1 Event number: 0 Major, minor: 253, 0 Number of targets: 2 UUID: LVM-jUqeLC.....
3. To get DM device info in column wise:
# dmsetup info -c /dev/VG00/LV00 # dmsetup info -C /dev/VG00/LV00 # dmsetup info -c /dev/VG00/LV00 Name Maj Min Stat Open Targ Event UUID VG00-LV00 253 0 L--w 1 2 0 LVM-jUqeLvGB9........
4. To list the DM device dependencies:
# dmsetup deps /dev/VG00/LV00 # dmsetup deps /dev/VG00/LV00 2 dependencies : (8, 48) (8, 32)
5. To get the status of a DM device:
# dmsetup status /dev/VG00/LV00 # dmsetup status /dev/VG00/LV00 0 20963328 linear 20963328 8192 linear
6. To destroy the inactive table for a device:
# dmsetup clear /dev/VG00/LV00
7. To send message to target:
# dmsetup device_name sector message # dmsetup /dev/VG00/LV00 0 "My Logical device"
8. To remove a device (this will cause data loss):
# dmsetup remove /dev/VG00/LV00
9. To remove all the devices:
# dmsetup remove_all
10. To rename the device:
# dmsetup /dev/VG00/LV00 /dev/VG00/LV04
11. To suspend a device:
# dmsetup suspend --nolockfs /dev/VG00/LV00 # dmsetup suspend --noflush /dev/VG00/LV00
12. To un-suspend a device:
# dmsetup resume /dev/VG00/LV00
13. To output the table for a device:
# dmsetup table /dev/VG00/LV00 # dmsetup table /dev/VG00/LV00 0 20963328 linear 8:32 2048 20963328 8192 linear 8:48 2048
14. To get the dmsetup version info:
# dmsetup version # dmsetup version Library version: 1.02.53 (2010-07-28) Driver version: 4.17.0
15. To display the help information:
# dmsetup -h