SYNOPSIS
dmsetup create device_name [-u uuid] [--notable] [table_file]
dmsetup remove [-f|--force] device_name
dmsetup remove_all [-f|--force]
dmsetup suspend [--nolockfs] device_name
dmsetup resume device_name
dmsetup load device_name [table_file]
dmsetup clear device_name
dmsetup reload device_name [table_file]
dmsetup rename device_name new_name
dmsetup ls [--target target_type] [--exec command] [--tree [-o
options]]
dmsetup info [device_name]
dmsetup info -c|-C|--columns [--noheadings] [-o name] [device_name]
dmsetup deps [device_name]
dmsetup status [--target target_type] [device_name]
dmsetup table [--target target_type] [device_name]
dmsetup wait device_name [event_nr]
dmsetup mknodes [device_name]
dmsetup targets
dmsetup version
devmap_name major minor
devmap_name major:minor
DESCRIPTION
dmsetup manages logical devices that use the device-mapper driver.
Devices are created by loading a table that specifies a target for each
sector (512 bytes) in the logical device.
The first argument to dmsetup is a command. The second argument is the
logical device name or uuid.
Invoking the command as devmap_name is equivalent to
dmsetup info -c --noheadings -j major -m minor.
OPTIONS
-c|-C|--columns
Display output in columns rather than as Field: Value lines.
-j|--major major
Specify the major number.
-m|--minor minor
Specify the minor number.
-n|--noheadings
Suppress the headings line when using columnar output.
--noopencount
Tell the kernel not to supply the open reference count for the
device.
Produce additional output.
--version
Display the library and kernel driver version.
COMMANDS
create device_name [-u uuid] [--notable] [table_file]
Creates a device with the given name. If table_file is sup‐
plied, the table is loaded and made live. Otherwise a table is
read from standard input unless --notable is used. The optional
uuid can be used in place of device_name in subsequent dmsetup
commands. If successful a device will appear as /dev/device-
mapper/<device-name>. See below for information on the table
format.
deps [device_name]
Outputs a list of (major, minor) pairs for devices referenced by
the live table for the specified device.
info [device_name]
Outputs some brief information about the device in the form:
State: SUSPENDED|ACTIVE, READ-ONLY
Tables present: LIVE and/or INACTIVE
Open reference count
Last event sequence number (used by wait)
Major and minor device number
Number of targets in the live table
UUID
ls [--target target_type] [--exec command] [--tree [-o options]]
List device names. Optionally only list devices that have at
least one target of the specified type. Optionally execute a
command for each device. The device name is appended to the
supplied command. --tree displays dependencies between devices
as a tree. It accepts a comma-separate list of options. Some
specify the information displayed against each node:
device/nodevice; active, open, rw, uuid. Others specify how the
tree is displayed: ascii, utf, vt100; compact, inverted,
notrunc.
load|reload
device_name [table_file]
Loads table_file into the inactive table slot for device_name.
If table_file is not supplied, reads a table from standard
input.
mknodes
[device_name]
Ensure that the node in /dev/mapper for device_name is correct.
If no device_name is supplied, ensure that all nodes in
/dev/mapper correspond to mapped devices currently loaded by the
device-mapper kernel driver, adding, changing or removing nodes
Attempts to remove all device definitions i.e. reset the driver.
Use with care! From version 4.8.0 onwards, if devices can’t be
removed because uninterruptible processess are waiting for I/O
to return from them, adding --force will replace the table with
one that fails all I/O, which might allow the process to be
killed. This also runs mknodes afterwards.
rename device_name new_name
Renames a device.
resume device_name
Un-suspends a device. If an inactive table has been loaded, it
becomes live. Postponed I/O then gets re-queued for processing.
status [--target target_type] [device_name]
Outputs status information for each of the device’s targets.
With --target, only information relating to the specified target
type is displayed.
suspend
[--nolockfs] device_name
Suspends a device. Any I/O that has already been mapped by the
device but has not yet completed will be flushed. Any further
I/O to that device will be postponed for as long as the device
is suspended. If there’s a filesystem on the device which sup‐
ports the operation, an attempt will be made to sync it first
unless --nolockfs is specified.
table [--target target_type] [device_name]
Outputs the current table for the device in a format that can be
fed back in using the create or load commands. With --target,
only information relating to the specified target type is dis‐
played.
targets
Displays the names and versions of the currently-loaded targets.
version
Outputs version information.
wait device_name [event_nr]
Sleeps until the event counter for device_name exceeds event_nr.
Use -v to see the event number returned. To wait until the next
event is triggered, use info to find the last event number.
TABLE FORMAT
Each line of the table specifies a single target and is of the form:
logical_start_sector num_sectors target_type target_args
There are currently three simple target types available together with
more complex optional ones that implement snapshots and mirrors.
etc.
error
Errors any I/O that goes to this area. Useful for testing or
for creating devices with holes in them.
EXAMPLES
# A table to join two disks together
0 1028160 linear /dev/hda 0
1028160 3903762 linear /dev/hdb 0
# A table to stripe across the two disks,
# and add the spare space from
# hdb to the back of the volume
0 2056320 striped 2 32 /dev/hda 0 /dev/hdb 0
2056320 2875602 linear /dev/hdb 1028160
AUTHORS
Original version: Joe Thornber (thornber@sistina.com)
SEE ALSO
Device-mapper resource page: http://sources.redhat.com/dm/
Linux Apr 06 2006 DMSETUP(8)
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