# dmsetup

## NAME



           dmsetup — low level logical volume management
    


## SYNOPSIS



    
           **dmsetup clear** _device_name_
           **dmsetup create** _device_name_ [**-n** |**--notable** |**--table** _table_ |_table_file_]
                    [**--readahead**[**+**]_sectors_ |**auto** |**none**] [**-u** |**--uuid** _uuid_]
                    [**--addnodeoncreate** |**--addnodeonresume**]
           **dmsetup create --concise**[_concise_device_specification_]
           **dmsetup deps**[**-o** _options_] [_device_name_...]
           **dmsetup help**[**-c** |**-C** |**--columns**]
           **dmsetup info**[_device_name_...]
           **dmsetup info -c** |**-C** |**--columns**[**--count** _count_] [**--interval** _seconds_]
                    [**--noheadings**] [**-o** _fields_] [**-O** |**--sort** _sort_fields_]
                    [**--nameprefixes**] [**--separator** _separator_] [_device_name_]
           **dmsetup load** _device_name_ [**--table** _table_ |_table_file_]
           **dmsetup ls**[**--target** _target_type_] [**-o** _options_] [**--exec** _command_]
                    [**--tree**]
           **dmsetup mangle**[_device_name_...]
           **dmsetup measure**[_device_name_...]
           **dmsetup message** _device_name sector message_
           **dmsetup mknodes**[_device_name_...]
           **dmsetup reload** _device_name_ [**--table** _table_ |_table_file_]
           **dmsetup  remove**[**-f** |**--force**] [**--retry**] [**--deferred**] _device_name_...
    
           **dmsetup remove_all**[**-f** |**--force**] [**--deferred**]
           **dmsetup rename** _device_name new_name_
           **dmsetup rename** _device_name_ **--setuuid** _uuid_
           **dmsetup resume** _device_name_...  [**--addnodeoncreate** |**--addnodeonre‐**
                    **sume**] [**--noflush**] [**--nolockfs**] [**--readahead**
                    [**+**]_sectors_ |**auto** |**none**]
           **dmsetup setgeometry** _device_name cyl head sect start_
           **dmsetup splitname** _device_name_ [_subsystem_]
           **dmsetup stats** _command_ [_options_]
           **dmsetup status**[**--target** _target_type_] [**--noflush**] [_device_name_...]
    
           **dmsetup suspend**[**--nolockfs**] [**--noflush**] _device_name_...
           **dmsetup table**[**--concise**] [**--target** _target_type_] [**--showkeys**]
                    [_device_name_...]
           **dmsetup targets**
           **dmsetup udevcomplete** _cookie_
           **dmsetup udevcomplete_all**[_age_in_minutes_]
           **dmsetup udevcookie**
           **dmsetup udevcreatecookie**
           **dmsetup udevflags** _cookie_
           **dmsetup udevreleasecookie**[_cookie_]
           **dmsetup version**
           **dmsetup wait**[**--noflush**] _device_name_ [_event_nr_]
           **dmsetup wipe_table** _device_name_...  [**-f** |**--force**] [**--noflush**]
                    [**--nolockfs**]
    
           **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  dmsetup  tool as **devmap_name**(which is not normally
           distributed and is  supported  only  for  historical  reasons)  is
           equivalent to **dmsetup info -c --noheadings -j** _major_ **-m** _minor_.
    


## OPTIONS



           **--addnodeoncreate**
                  Ensure _/dev/mapper_ node exists after **dmsetup create**.
    
           **--addnodeonresume**
                  Ensure _/dev/mapper_ node exists after **dmsetup resume**(de‐
                  fault with udev).
    
           **--checks**
                  Perform additional checks on the operations requested and
                  report potential problems.  Useful when debugging scripts.
                  In some cases these checks may slow down operations notice‐
                  ably.
    
           **-c** |**-C** |**--columns**
                  Display output in columns rather than as Field: Value
                  lines.
    
           **--count** _count_
                  Specify the number of times to repeat a report. Set this to
                  zero continue until interrupted.  The default interval is
                  one second.
    
           **-f** |**--force**
                  Try harder to complete operation.
    
           **-h** |**--help**
                  Outputs a summary of the commands available, optionally in‐
                  cluding the list of report fields (synonym with **help** com‐
                  mand).
    
           **--inactive**
                  When returning any table information from the kernel report
                  on the inactive table instead of the live table.  Requires
                  kernel driver version 4.16.0 or above.
    
           **--interval** _seconds_
                  Specify the interval in seconds between successive itera‐
                  tions for repeating reports. If **--interval** is specified but
                  **--count** is not, reports will continue to repeat until in‐
                  terrupted.  The default interval is one second.
    
           **--manglename auto** |**hex** |**none**
                  Mangle any character not on a whitelist using mangling_mode
                  when processing device-mapper device names and UUIDs. The
                  names and UUIDs are mangled on input and unmangled on out‐
                  put where the mangling mode is one of: **auto**(only do the
                  mangling if not mangled yet, do nothing if already mangled,
                  error on mixed), **hex**(always do the mangling) and **none**(no
                  mangling).  Default mode is **auto**.  Character whitelist:
                  0-9, A-Z, a-z, #+-.:=@_. This whitelist is also supported
                  by udev. Any character not on a whitelist is replaced with
                  its hex value (two digits) prefixed by \x.  Mangling mode
                  could be also set through **DM_DEFAULT_NAME_MANGLING_MODE** en‐
                  vironment variable.
    
           **-j** |**--major** _major_
                  Specify the major number.
    
           **-m** |**--minor** _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.  Use‐
                  ful with **--noheadings** to produce a list of field=value
                  pairs that can 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 outstanding 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 suspend‐
                  ing 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 re‐
                  moving devices.
    
           **-o** |**--options** _options_
                  Specify which fields to display.
    
           **--readahead**[**+**]_sectors_ |**auto** |**none**
                  Specify read ahead size in units of sectors.  The default
                  value is **auto** which allows the kernel to choose a suitable
                  value automatically.  The **+** prefix lets you specify a mini‐
                  mum value which will not be used if it is smaller than the
                  value chosen by the kernel.  The value **none** is equivalent
                  to specifying zero.
    
           **-r** |**--readonly**
                  Set the table being loaded read-only.
    
           **-S** |**--select** _selection_
                  Process only items that match _selection_ criteria.  If the
                  command is producing report output, adding the "selected"
                  column (**-o selected**) displays all rows and shows 1 if the
                  row matches the _selection_ and 0 otherwise. The selection
                  criteria are defined by specifying column names and their
                  valid values while making use of supported comparison oper‐
                  ators. As a quick help and to see full list of column names
                  that can be used in selection and the set of supported se‐
                  lection operators, check the output of **dmsetup in‐**
                  **fo -c -S help** command.
    
           **--table** _table_
                  Specify a one-line table directly on the command line.  See
                  below for more information on the table format.
    
           **--udevcookie** _cookie_
                  Use cookie for udev synchronisation.  Note: Same cookie
                  should be used for same type of operations i.e. creation of
                  multiple different devices. It's not adviced to combine
                  different operations on the single device.
    
           **-u** |**--uuid** _uuid_
                  Specify the _uuid_.
    
           **-y** |**--yes**
                  Answer yes to all prompts automatically.
    
           **-v** |**--verbose**[**-v** |**--verbose**]
                  Produce additional output.
    
           **--verifyudev**
                  If udev synchronisation is enabled, verify that udev opera‐
                  tions get performed correctly and try to fix up the device
                  nodes afterwards if not.
    
           **--version**
                  Display the library and kernel driver version.
    


## COMMANDS



    
           **clear** _device_name_
                  Destroys the table in the inactive table slot for de‐
                  vice_name.
    
           **create** _device_name_ [**-n** |**--notable** |**--table** _table_ |_table_file_]
                  [**--readahead**[**+**]_sectors_ |**auto** |**none**] [**-u** |**--uuid** _uuid_]
                  [**--addnodeoncreate** |**--addnodeonresume**]
                  Creates  a  device  with  the  given name.  If _table_ or _ta‐_
                  _ble_file_ is supplied, the table is loaded  and  made  live.
                  Otherwise  a table is read from standard input unless **--no‐**
                  **table** is used.  The optional _uuid_ can be used in  place  of
                  device_name  in subsequent dmsetup commands.  If successful
                  the device will appear in table and  for  live  device  the
                  node  _/dev/mapper/device_name_  is  created.   See below for
                  more information on the table format.
    
           **create --concise**[_concise_device_specification_]
                  Creates one or more devices from a concise device  specifi‐
                  cation.   Each  device  is  specified  by a comma-separated
                  list: name, uuid, minor number, flags, comma-separated  ta‐
                  ble  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 spec‐
                  ifications 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 FORMAT 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 cus‐
                  tomised by following _options_ : **devno**(major and minor  pair,
                  used  by  default), **blkdevname**(block device name), **devname**
                  (map name for device-mapper devices,  equal  to  blkdevname
                  otherwise).
    
           **help**[**-c** |**-C** |**--columns**]
                  Outputs a summary of the commands available, optionally in‐
                  cluding the list of report fields.
    
           **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
    
           **info -c** |**-C** |**--columns**[**--count** _count_] [**--interval** _seconds_]
                  [**--noheadings**] [**-o** _fields_] [**-O** |**--sort** _sort_fields_]
                  [**--nameprefixes**] [**--separator** _separator_] [_device_name_]
                  Output you can customise.  Fields are  comma-separated  and
                  chosen  from  the following list: **name** , **major** , **minor** , **attr** ,
                  **open** , **segments** ,  **events** ,  **uuid**.   Attributes  are:  (**L**)ive,
                  (**I**)nactive,  (**s**)uspended,  (**r**)ead-only, read-(**w**)rite.  Pre‐
                  cede the list with '**+** ' to append to the  default  selection
                  of columns instead of replacing it.  Precede any sort field
                  with '**-** ' for a reverse sort on that column.
    
           **ls**[**--target** _target_type_] [**-o** _options_] [**--exec** _command_] [**--tree**]
                  List  device names.  Optionally only list devices that have
                  at least one target of the specified type.  Optionally exe‐
                  cute a command for each device.  The device name is append‐
                  ed to the supplied command.  Device names on output can  be
                  customised  by  following  options:  **devno**(major and minor
                  pair, used by default), **blkdevname**(block device name), **de‐**
                  **vname**(map name for device-mapper devices, equal to blkdev‐
                  name otherwise).  **--tree** displays dependencies between  de‐
                  vices  as  a tree.  It accepts a comma-separate list of _op‐_
                  _tions_.  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
                  standard input.
    
           **mangle**[_device_name_...]
                  Ensure existing device-mapper _device_name_ and  UUID  is  in
                  the  correct mangled form containing only whitelisted char‐
                  acters (supported by udev) and do a  rename  if  necessary.
                  Any character not on the whitelist will be mangled based on
                  the  **--manglename** setting. Automatic rename works only for
                  device names and not for device UUIDs  because  the  kernel
                  does not allow changing the UUID of active devices. Any in‐
                  correct  UUIDs  are reported only and they must be manually
                  corrected by deactivating the device first and then reacti‐
                  vating it with proper mangling mode used (see  also  **--man‐**
                  **glename**).
    
           **measure**[_device_name_...]
                  Show the data that _device_name_ would report to the IMA sub‐
                  system  if a measurement was triggered at the current time.
                  This is for debugging and does not actually trigger a  mea‐
                  surement.
    
           **message** _device_name sector message_
                  Send message to target. If sector not needed use 0.
    
           **mknodes**[_device_name_...]
                  Ensure that the node in _/dev/mapper_ for _device_name_ is cor‐
                  rect.  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 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 re‐
                  place the table with one that fails  all  I/O.   **--deferred**
                  will  enable  deferred removal of open devices - the device
                  will be removed when the last user closes it. The  deferred
                  removal  feature  is  supported since version 4.27.0 of the
                  device-mapper driver available in upstream  kernel  version
                  3.13.   (Use **dmsetup version** to check this.)  If an attempt
                  to remove a device fails, perhaps  because  a  process  run
                  from  a  quick udev rule temporarily opened the device, the
                  **--retry** option will cause the operation to be retried for a
                  few seconds before failing.  Do  NOT  combine  **--force** and
                  **--udevcookie** ,  as  udev  may start to process udev rules in
                  the middle of error target replacement and result in nonde‐
                  terministic 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!
                  Open devices cannot be removed, but adding **--force** will re‐
                  place  the  table  with one that fails all I/O.  **--deferred**
                  will enable deferred removal of open devices -  the  device
                  will be removed when the last user closes it.  The deferred
                  removal  feature  is  supported since version 4.27.0 of the
                  device-mapper driver available in upstream  kernel  version
                  3.13.
    
           **rename** _device_name new_name_
                  Renames a device.
    
           **rename** _device_name_ **--setuuid** _uuid_
                  Sets  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 processing.
    
           **setgeometry** _device_name cyl head sect start_
                  Sets 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 by concatenating the names of the Volume Group, Logi‐
                  cal  Volume and any internal Layer with a hyphen as separa‐
                  tor.  Any hyphens within the names are  doubled  to  escape
                  them.   The precise encoding might change without notice in
                  any future release, so we recommend 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 tar‐
                  gets.  With **--target** ,  only  information  relating  to  the
                  specified  target  type  any is displayed.  With **--noflush** ,
                  the thin target (from version  1.3.0)  doesn't  commit  any
                  outstanding  changes  to  disk before reporting its statis‐
                  tics.
    
           **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
                  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.  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  the  device  to  remain  un‐
                  flushed.
    
           **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
                  **--target** , only information relating to the specified target
                  type is displayed.  Real encryption keys are suppressed  in
                  the table output for crypt and integrity targets unless the
                  **--showkeys** parameter  is  supplied.  Kernel key references
                  prefixed with **:** are not affected by the parameter  and  get
                  displayed  always (crypt target only).  With **--concise** , the
                  output is presented concisely on  a  single  line.   Commas
                  then  separate  the  name, uuid, minor device number, flags
                  ('ro' or 'rw') and the table (if present). Semi-colons sep‐
                  arate devices. Backslashes escape any  commas,  semi-colons
                  or backslashes.  See CONCISE FORMAT below.
    
           **targets**
                  Displays  the  names  and  versions of the currently-loaded
                  targets.
    
           **udevcomplete** _cookie_
                  Wake 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 min‐
                  utes.  Any process waiting on a cookie will be resumed  im‐
                  mediately.
    
           **udevcookie**
                  List  all  existing  cookies. Cookies are system-wide sema‐
                  phores with keys prefixed by two predefined bytes (0x0D4D).
    
           **udevcreatecookie**
                  Creates a new cookie to synchronize actions with udev  pro‐
                  cessing.   The  output is a cookie value. Normally we don't
                  need to create cookies since dmsetup creates  and  destroys
                  them  for each action automatically. However, we can gener‐
                  ate one explicitly to group several  actions  together  and
                  use  only one cookie instead. We can define a cookie to use
                  for each relevant command by using **--udevcookie** option. Al‐
                  ternatively, we can export this value into the  environment
                  of  the  dmsetup  process as **DM_UDEV_COOKIE** variable and it
                  will be used automatically with all subsequent commands un‐
                  til it is unset.  Invoking this command will create system-
                  wide semaphore that needs to be cleaned  up  explicitly  by
                  calling udevreleasecookie command.
    
           **udevflags** _cookie_
                  Parses  given  _cookie_  value  and extracts any udev control
                  flags encoded.  The output is  in  environment  key  format
                  that is suitable 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  are  always  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
                  the  cookie  is not given directly, the command will try to
                  use a value defined by **DM_UDEV_COOKIE** environment variable.
    
           **version**
                  Outputs 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 the next event is triggered, use  **info** to  find
                  the  last  event  number.   With **--noflush** , the thin target
                  (from version 1.3.0) doesn't commit 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 sent to the device.  If successful, this should release
                  any devices held open by the device's table(s).
    


## 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_
    
           Simple target types and target args include:
    
           **linear** _destination_device start_sector_
                  The 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 1
                          LV chunk 2 → hdb1, chunk 1
                          LV chunk 3 → hda1, chunk 2
                          LV chunk 4 → hdb1, chunk 2
                          etc.
    
           **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
                  failing devices when testing.
    
           **mirror** Mirrors data across two or more devices.
    
           **multipath**
                  Mediates access through multiple paths to the same device.
    
           **raid** Offers an interface to the kernel's software raid driver,
                  md.
    
           **snapshot**
                  Supports snapshots of devices.
    
           **thin** , **thin-pool**
                  Supports 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 Documentation/de‐
           vice-mapper directory in the kernel source tree.  (Your distribu‐
           tion might include a copy of this information in the documentation
           directory for the device-mapper package.)
    


## 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
    


## CONCISE FORMAT



           A concise representation of one of more devices.
    
           - A comma separates the fields of each device.
           - A semi-colon separates devices.
    
           The representation of a device takes the form:
                  <name>,<uuid>,<minor>,<flags>,<table>[,<table>+]
                  [;<dev_name>,<uuid>,<minor>,<flags>,<table>[,<table>+]]
    
           The fields are:
    
           **name** The name of the device.
    
           **uuid** The UUID of the device (or empty).
    
           **minor** The minor number of the device.  If empty, the kernel as‐
                  signs a suitable minor number.
    
           **flags** Supported flags are:
                  **ro** Sets the table being loaded for the device read-only
                  **rw** Sets the table being loaded for the device read-write
                  (default)
    
           **table** One line of the table. See TABLE FORMAT above.
    


## EXAMPLES



           # A simple linear read-only device
           test-linear-small,,,ro,0 2097152 linear /dev/loop0 0,2097152
           2097152 linear /dev/loop1 0
           # Two linear devices
           test-linear-small,,,,0 2097152 linear /dev/loop0 0;test-
           linear-large,,,,0 2097152 linear /dev/loop1 0, 2097152 2097152
           linear /dev/loop2 0
    


## ENVIRONMENT VARIABLES



           **DM_DEV_DIR**
                  The device directory name.  Defaults to "_/dev_ " and must be
                  an absolute path.
    
           **DM_UDEV_COOKIE**
                  A cookie to use for all relevant commands to synchronize
                  with udev processing.  It is an alternative to using **--ude‐**
                  **vcookie** option.
    
           **DM_DEFAULT_NAME_MANGLING_MODE**
                  A default mangling mode. Defaults to "**auto** " and it is an
                  alternative to using **--manglename** option.
    


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