Provided by: dmsetup_1.02.05-1ubuntu1_i386
dmsetup - low level logical volume management
dmsetup create device_name [-u uuid] [--notable] [table_file]
dmsetup remove device_name
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
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]
devmap_name major minor
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.
Display output in columns rather than as Field: Value lines.
Specify the major number.
Specify the minor number.
Suppress the headings line when using columnar output.
Tell the kernel not to supply the open reference count for the
When creating a device, don’t load any table.
Specify which fields to display. Only -o name is supported.
Set the table being loaded read-only.
Specify the uuid.
Produce additional output.
Display the library and kernel driver version.
create device_name [-u uuid] [--notable] [table_file]
Creates a device with the given name. If table_file is
supplied, 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.
Outputs a list of (major, minor) pairs for devices referenced by
the live table for the specified device.
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
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,
Loads table_file into the inactive table slot for device_name.
If table_file is not supplied, reads a table from standard
Removes a device. It will no longer be visible to dmsetup and
will be deleted when its open_count is zero.
Attempts to remove all device definitions i.e. reset the driver.
Use with care!
rename device_name new_name
Renames a device.
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.
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
supports 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
Displays the names and versions of the currently-loaded targets.
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.
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.
linear destination_device start_sector
The traditional linear mapping.
num_stripes chunk_size [destination start_sector]+
Creates a striped area.
e.g. striped 2 32 /dev/hda1 0 /dev/hdb1 0 will map the first
chunk (16k) as follows:
LV chunk 1 -> hda1, chunk 1
LV chunk 2 -> hdb1, chunk 1
LV chunk 3 -> hda1, chunk 2
LV chunk 4 -> hdb1, chunk 2
Errors any I/O that goes to this area. Useful for testing or
for creating devices with holes in them.
# 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
Original version: Joe Thornber (firstname.lastname@example.org)
Device-mapper resource page: http://sources.redhat.com/dm/