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       dmsetup - low level logical volume management

       dmsetup help [-c|-C|--columns]
       dmsetup create device_name [-u uuid] [--notable | --table <table> | ta-
       dmsetup remove [-f|--force] device_name
       dmsetup remove_all [-f|--force]
       dmsetup suspend [--nolockfs] [--noflush] device_name
       dmsetup resume device_name
       dmsetup load device_name [--table <table> | table_file]
       dmsetup clear device_name
       dmsetup reload device_name [--table <table> | table_file]
       dmsetup rename device_name new_name
       dmsetup message device_name sector message
       dmsetup ls [--target target_type] [--exec command] [--tree [-o
       dmsetup info [device_name]
       dmsetup info -c|-C|--columns [--noheadings] [--separator separator] [-o
       fields] [-O|--sort sort_fields] [device_name]
       dmsetup deps [device_name]
       dmsetup status [--target target_type] [device_name]
       dmsetup table [--target target_type] [--showkeys] [device_name]
       dmsetup wait device_name [event_nr]
       dmsetup mknodes [device_name]
       dmsetup udevcreatecookie
       dmsetup udevreleasecookie [cookie]
       dmsetup udevflags cookie
       dmsetup udevcomplete cookie
       dmsetup udevcomplete_all
       dmsetup udevcookies
       dmsetup targets
       dmsetup version
       dmsetup setgeometry device_name cyl head sect start
       dmsetup splitname device_name [subsystem]

       devmap_name major minor
       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.

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

	      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.

       -j|--major major
	      Specify the major number.

       -m|--minor minor
	      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.

       --udevcookie cookie
	      Use cookie for udev synchronisation.

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

	      Do not synchronise with udev when creating, renaming or removing

	      Specify which fields to display.

	      Set the table being loaded read-only.

       --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 minimum value
	      which will not be used if it is smaller than the value chosen by
	      the kernel.  "None" is equivalent to specifying zero.

       --table <table>
	      Specify a one-line table directly on the command line.

	      Specify the uuid.

	      Answer yes to all prompts automatically.

       -v|--verbose [-v|--verbose]
	      Produce additional output.

	      Display the library and kernel driver version.

       create device_name [-u uuid] [--notable | --table <table> | table_file]
	      Creates  a device with the given name.  If table_file or <table>
	      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  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.

       help   [-c|-C|--columns]
	      Outputs a summary of the commands available, optionally  includ-
	      ing the list of report fields.

       info   [device_name]
	      Outputs some brief information about the device in the form:
		  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

       info   -c|-C|--columns	[--noheadings]	 [--separator  separator]  [-o
	      fields] [-O|--sort sort_fields] [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
	      on that 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 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,

	      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 stan-
	      dard input.

	      device_name sector message
	      Send message to target. If sector not needed use 0.

	      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
	      as necessary.

       remove [-f|--force] device_name
	      Removes a device.  It will no  longer  be  visible  to  dmsetup.
	      Open  devices  cannot  be removed except with older kernels that
	      contain a version of device-mapper prior to 4.8.0.  In this case
	      the  device  will  be deleted when its open_count drops to zero.
	      From version 4.8.0 onwards, if a device can't be removed because
	      an uninterruptible process is waiting for I/O to return from it,
	      adding --force will replace the table with one  that  fails  all
	      I/O, which might allow the process to be killed.

	      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 processes 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.

	      device_name cyl head sect start
	      Sets the device geometry to C/H/S.

	      device_name [subsystem]
	      Splits  given  device name into subsystem constituents.  Default
	      subsystem is LVM.

       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.

	      [--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 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 the
	      device to remain unflushed.

       table  [--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  dis-
	      played.	Encryption keys are suppressed in the table output for
	      the crypt target unless the --showkeys parameter is supplied.

	      Displays the names and versions of the currently-loaded targets.

	      Creates a new cookie to synchronize actions with	udev  process-
	      ing.   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 generate 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. Alternatively, 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	until  it is unset.  Invoking this command will create
	      system-wide semaphore that needs to be cleaned up explicitly  by
	      calling udevreleasecookie command.

	      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.

	      Parses 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   ouput  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.

	      Wake  any  processes  that are waiting for udev to complete pro-
	      cessing the specified cookie.

	      Remove all cookies. Any process waiting  on  a  cookie  will  be
	      resumed immediately.

	      List  all  existing  cookies. Cookies are system-wide semaphores
	      with keys prefixed by two predefined bytes (0x0D4D).

	      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

	      The  device  directory  name.  Defaults to "/dev" and must be an
	      absolute path.

	      A cookie to use for all relevant commands  to  synchronize  with
	      udev  processing.   It  is  an alternative to using --udevcookie

       Original version: Joe Thornber (thornber@sistina.com)

       Device-mapper resource page: http://sources.redhat.com/dm/

Linux				  Apr 06 2006			    DMSETUP(8)

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