--addnodeoncreate

Ensure /dev/mapper node exists after dmsetup create.

--addnodeonresume

Ensure /dev/mapper node exists after dmsetup resume (default with udev).

--checks

Perform additional checks on the operations requested and report potential problems. Useful when debugging scripts. In somecases these checks may slow down operations noticeably.

-c|-C|--columns

Display output in columns rather than as Field: Value lines.

--count

Specify the number of times to repeat a report. Set this to zero continue until interrupted. The default interval is one sec‐ond.

-f|--force

Try harder to complete operation.

-h|--help

Outputs a summary of the commands available, optionally including the list of report fields (synonym with help command).

--inactive

When returning any table information from the kernel report on the inactive table instead of the live table. Requires kerneldriver version 4.16.0 or above.

--interval

Specify the interval in seconds between successive iterations for repeating reports. If --interval is specified but --count isnot, reports will continue to repeat until interrupted. The default interval is one second.

--manglename

Mangle any character not on a whitelist using mangling_mode when processing device-mapper device names and UUIDs. The namesand UUIDs are mangled on input and unmangled on output where the mangling mode is one of: auto (only do the mangling if notmangled yet, do nothing if already mangled, error on mixed), hex (always do the mangling) and none (no mangling). Defaultmode is auto. Character whitelist: 0-9, A-Z, a-z, #+-.:=@_. This whitelist is also supported by udev. Any character not on awhitelist is replaced with its hex value (two digits) prefixed by \x. Mangling mode could be also set throughDM_DEFAULT_NAME_MANGLING_MODE environment variable.

-j|--major

Specify the major number.

-m|--minor

Specify the minor number.

-n|--notable

When creating a device, don't load any table.

--nameprefixes

Add a "DM_" prefix plus the field name to the output. Useful with --noheadings to produce a list of field=value pairs thatcan be used to set environment variables (for example, in udev(7) rules).

--noheadings

Suppress the headings line when using columnar output.

--noflush

Do not flush outstading I/O when suspending a device, or do not commit thin-pool metadata when obtaining thin-pool status.

--nolockfs

Do not attempt to synchronize filesystem eg, when suspending a device.

--noopencount

Tell the kernel not to supply the open reference count for the device.

--noudevrules

Do not allow udev to manage nodes for devices in device-mapper directory.

--noudevsync

Do not synchronise with udev when creating, renaming or removing devices.

-o|--options

Specify which fields to display.

--readahead

Specify read ahead size in units of sectors. The default value is auto which allows the kernel to choose a suitable valueautomatically. The + prefix lets you specify a minimum value which will not be used if it is smaller than the value chosen bythe kernel. The value none is equivalent to specifying zero.

-r|--readonly

Set the table being loaded read-only.

-S|--select

Process only items that match selection criteria. If the command is producing report output, adding the "selected" column (-oselected) displays all rows and shows 1 if the row matches the selection and 0 otherwise. The selection criteria are definedby specifying column names and their valid values while making use of supported comparison operators. As a quick help and tosee full list of column names that can be used in selection and the set of supported selection operators, check the output ofdmsetup info -c -S help command.

--table

Specify a one-line table directly on the command line. See below for more information on the table format.

--udevcookie

Use cookie for udev synchronisation. Note: Same cookie should be used for same type of operations i.e. creation of multipledifferent devices. It's not adviced to combine different operations on the single device.

-u|--uuid

Specify the uuid.

-y|--yes

Answer yes to all prompts automatically.

-v|--verbose

Produce additional output.

--verifyudev

If udev synchronisation is enabled, verify that udev operations get performed correctly and try to fix up the device nodesafterwards if not.

--version

Display the library and kernel driver version.COMMANDSclear device_nameDestroys the table in the inactive table slot for device_name.create device_name [-u|--uuid uuid] [--addnodeoncreate|--addnodeonresume] [-n|--notable|--table table|table_file] [--readahead[+]sectors|auto|none]Creates a device with the given name. If table or table_file is supplied, the table is loaded and made live. Otherwise a ta‐ble is read from standard input unless --notable is used. The optional uuid can be used in place of device_name in subsequentdmsetup commands. If successful the device will appear in table and for live device the node /dev/mapper/device_name is cre‐ated. See below for more information on the table format.create --concise [concise_device_specification]Creates one or more devices from a concise device specification. Each device is specified by a comma-separated list: name,uuid, minor number, flags, comma-separated table lines. Flags defaults to read-write (rw) or may be read-only (ro). Uuid,minor number and flags are optional so those fields may be empty. A semi-colon separates specifications of different devices.Use a backslash to escape the following character, for example a comma or semi-colon in a name or table. See also CONCISE FOR‐MAT below.deps [-o options] [device_name...]Outputs a list of devices referenced by the live table for the specified device. Device names on output can be customised byfollowing options: devno (major and minor pair, used by default), blkdevname (block device name), devname (map name fordevice-mapper devices, equal to blkdevname otherwise).help [-c|-C|--columns]Outputs a summary of the commands available, optionally including the list of report fields.info [device_name...]Outputs some brief information about the device in the form:State: SUSPENDED|ACTIVE, READ-ONLYTables present: LIVE and/or INACTIVEOpen reference countLast event sequence number (used by wait)Major and minor device numberNumber of targets in the live tableUUIDinfo -c|-C|--columns [--count count] [--interval seconds] [--nameprefixes] [--noheadings] [-o fields] [-O|--sort sort_fields] [--sep‐arator separator] [device_name]Output you can customise. Fields are comma-separated and chosen from the following list: name, major, minor, attr, open, seg‐ments, events, uuid. Attributes are: (L)ive, (I)nactive, (s)uspended, (r)ead-only, read-(w)rite. Precede the list with '+'to append to the default selection of columns instead of replacing it. Precede any sort field with '-' for a reverse sort onthat column.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 acommand for each device. The device name is appended to the supplied command. Device names on output can be customised byfollowing options: devno (major and minor pair, used by default), blkdevname (block device name), devname (map name fordevice-mapper devices, equal to blkdevname otherwise). --tree displays dependencies between devices as a tree. It accepts acomma-separate list of options. Some specify the information displayed against each node: device/nodevice; blkdevname;active, open, rw, uuid. Others specify how the tree is displayed: ascii, utf, vt100; compact, inverted, notrunc.load|reload device_name [--table table|table_file]Loads table or table_file into the inactive table slot for device_name. If neither is supplied, reads a table from standardinput.mangle [device_name...]Ensure existing device-mapper device_name and UUID is in the correct mangled form containing only whitelisted characters (sup‐ported by udev) and do a rename if necessary. Any character not on the whitelist will be mangled based on the --manglenamesetting. Automatic rename works only for device names and not for device UUIDs because the kernel does not allow changing theUUID of active devices. Any incorrect UUIDs are reported only and they must be manually corrected by deactivating the devicefirst and then reactivating it with proper mangling mode used (see also --manglename).message device_name sector messageSend message to target. If sector not needed use 0.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 removingnodes as necessary.remove [-f|--force] [--retry] [--deferred] device_name...Removes a device. It will no longer be visible to dmsetup. Open devices cannot be removed, but adding --force will replacethe table with one that fails all I/O. --deferred will enable deferred removal of open devices - the device will be removedwhen the last user closes it. The deferred removal feature is supported since version 4.27.0 of the device-mapper driveravailable in upstream kernel version 3.13. (Use dmsetup version to check this.) If an attempt to remove a device fails, per‐haps because a process run from a quick udev rule temporarily opened the device, the --retry option will cause the operationto be retried for a few seconds before failing. Do NOT combine --force and --udevcookie, as udev may start to process udevrules in the middle of error target replacement and result in nondeterministic result.remove_all [-f|--force] [--deferred]Attempts to remove all device definitions i.e. reset the driver. This also runs mknodes afterwards. Use with care! Opendevices cannot be removed, but adding --force will replace the table with one that fails all I/O. --deferred will enabledeferred removal of open devices - the device will be removed when the last user closes it. The deferred removal feature issupported since version 4.27.0 of the device-mapper driver available in upstream kernel version 3.13.rename device_name new_nameRenames a device.rename device_name --setuuid uuidSets the uuid of a device that was created without a uuid. After a uuid has been set it cannot be changed.resume device_name... [--addnodeoncreate|--addnodeonresume] [--noflush] [--nolockfs] [--readahead [+]sectors|auto|none]Un-suspends a device. If an inactive table has been loaded, it becomes live. Postponed I/O then gets re-queued for process‐ing.setgeometry device_name cyl head sect startSets the device geometry to C/H/S.splitname device_name [subsystem]Splits given device name into subsystem constituents. The default subsystem is LVM. LVM currently generates device names byconcatenating the names of the Volume Group, Logical Volume and any internal Layer with a hyphen as separator. Any hyphenswithin the names are doubled to escape them. The precise encoding might change without notice in any future release, so werecommend you always decode using the current version of this command.stats command [options]Manages IO statistics regions for devices. See dmstats(8) for more details.status [--target target_type] [--noflush] [device_name...]Outputs status information for each of the device's targets. With --target, only information relating to the specified targettype any is displayed. With --noflush, the thin target (from version 1.3.0) doesn't commit any outstanding changes to diskbefore reporting its statistics.suspend [--nolockfs] [--noflush] 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 furtherI/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. Some targets such as recent(October 2006) versions of multipath may support the --noflush option. This lets outstanding I/O that has not yet reached thedevice to remain unflushed.table [--concise] [--target target_type] [--showkeys] [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 --tar‐get, only information relating to the specified target type is displayed. Real encryption keys are suppressed in the tableoutput for the crypt target unless the --showkeys parameter is supplied. Kernel key references prefixed with : are notaffected by the parameter and get displayed always. With --concise, the output is presented concisely on a single line. Com‐mas then separate the name, uuid, minor device number, flags ('ro' or 'rw') and the table (if present). Semi-colons separatedevices. Backslashes escape any commas, semi-colons or backslashes. See CONCISE FORMAT below.targetsDisplays the names and versions of the currently-loaded targets.udevcomplete cookieWake any processes that are waiting for udev to complete processing the specified cookie.udevcomplete_all [age_in_minutes]Remove all cookies older than the specified number of minutes. Any process waiting on a cookie will be resumed immediately.udevcookieList all existing cookies. Cookies are system-wide semaphores with keys prefixed by two predefined bytes (0x0D4D).udevcreatecookieCreates a new cookie to synchronize actions with udev processing. The output is a cookie value. Normally we don't need tocreate cookies since dmsetup creates and destroys them for each action automatically. However, we can generate one explicitlyto group several actions together and use only one cookie instead. We can define a cookie to use for each relevant command byusing --udevcookie option. Alternatively, we can export this value into the environment of the dmsetup process asDM_UDEV_COOKIE variable and it will be used automatically with all subsequent commands until it is unset. Invoking this com‐mand will create system-wide semaphore that needs to be cleaned up explicitly by calling udevreleasecookie command.udevflags cookieParses given cookie value and extracts any udev control flags encoded. The output is in environment key format that is suit‐able for use in udev rules. If the flag has its symbolic name assigned then the output is DM_UDEV_FLAG_<flag_name> = '1',DM_UDEV_FLAG<flag_position> = '1' otherwise. Subsystem udev flags don't have symbolic names assigned and these ones arealways reported as DM_SUBSYSTEM_UDEV_FLAG<flag_position> = '1'. There are 16 udev flags altogether.udevreleasecookie [cookie]Waits for all pending udev processing bound to given cookie value and clean up the cookie with underlying semaphore. If thecookie is not given directly, the command will try to use a value defined by DM_UDEV_COOKIE environment variable.versionOutputs version information.wait [--noflush] 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 thenext event is triggered, use info to find the last event number. With --noflush, the thin target (from version 1.3.0) doesn'tcommit any outstanding changes to disk before reporting its statistics.wipe_table device_name... [-f|--force] [--noflush] [--nolockfs]Wait for any I/O in-flight through the device to complete, then replace the table with a new table that fails any new I/O sentto the device. If successful, this should release any devices held open by the device's table(s).TABLE FORMATEach line of the table specifies a single target and is of the form:logical_start_sector num_sectors target_type target_argsSimple target types and target args include:linear destination_device start_sectorThe traditional linear mapping.striped 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 1LV chunk 2-> hdb1, chunk 1LV chunk 3-> hda1, chunk 2LV chunk 4-> hdb1, chunk 2etc.error Errors any I/O that goes to this area. Useful for testing or for creating devices with holes in them.zero Returns blocks of zeroes on reads. Any data written is discarded silently. This is a block-device equivalent of the/dev/zero character-device data sink described in null(4).More complex targets include:cache Improves performance of a block device (eg, a spindle) by dynamically migrating some of its data to a faster smaller device(eg, an SSD).crypt Transparent encryption of block devices using the kernel crypto API.delay Delays reads and/or writes to different devices. Useful for testing.flakey Creates a similar mapping to the linear target but exhibits unreliable behaviour periodically. Useful for simulating failingdevices when testing.mirror Mirrors data across two or more devices.multipathMediates access through multiple paths to the same device.raid Offers an interface to the kernel's software raid driver, md.snapshotSupports snapshots of devices.thin, thin-poolSupports thin provisioning of devices and also provides a better snapshot support.To find out more about the various targets and their table formats and status lines, please read the files in the Documenta‐tion/device-mapper directory in the kernel source tree. (Your distribution might include a copy of this information in the documen‐tation directory for the device-mapper package.)EXAMPLES# A table to join two disks together0 1028160 linear /dev/hda 01028160 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 volume0 2056320 striped 2 32 /dev/hda 0 /dev/hdb 02056320 2875602 linear /dev/hdb 1028160CONCISE FORMATA concise representation of one of more devices.

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A comma separates the fields of each device.