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DMSETUP(8)                   MAINTENTANCE COMMANDS                  DMSETUP(8)



NAME
       dmsetup - low level logical volume management

SYNOPSIS
       dmsetup create device_name [-u uuid] [--notable] [table_file]
       dmsetup remove device_name
       dmsetup remove_all
       dmsetup suspend 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
       dmsetup info [device_name]
       dmsetup deps [device_name]
       dmsetup status [device_name]
       dmsetup table [device_name]
       dmsetup wait device_name [event_nr]
       dmsetup mknodes [device_name]
       dmsetup targets
       dmsetup version

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.

OPTIONS
       -j|--major major
              Specify the major number to use on creation.

       -j|--minor minor
              Specify the minor number to use on creation.

       -r|--readonly
              Set the table being loaded read-only.

       -v|--verbose
              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
              List device names.

       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.

       remove device_name
              Removes  a  device.  It will no longer be visible to dmsetup and
              will be deleted when its open_count is zero.

       remove_all
              Attempts to remove all device definitions i.e. reset the driver.
              Use with care!

       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 [device_name]
              Outputs status information for each of the device's targets.

       suspend
              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.

       table  [device_name]
              Outputs the current table for the device in a format that can be
              fed back in using the create or load commands.

       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.


       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.


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 (thornberATsistina.com)


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



Linux                             Sep 17 2003                       DMSETUP(8)