Provided by: dmsetup_1.02.20-2ubuntu2_i386 bug

NAME

       dmsetup - low level logical volume management

SYNOPSIS

       dmsetup help [-c|-C|--columns]
       dmsetup create device_name [-u uuid] [--notable | --table <table> |
       table_file]
       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
       options]]
       dmsetup info [device_name]
       dmsetup info -c|-C|--columns [--noheadings] [--separator separator] [-o
       fields] [-O|--sort sort_fields] [device_name]
       dmsetup export [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]
       dmsetup targets
       dmsetup version
       dmsetup setgeometry device_name cyl head sect start

       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 command as devmap_name is equivalent to
       dmsetup info -c --noheadings -j major -m minor.

OPTIONS

       -c|-C|--columns
              Display output in columns rather than as Field: Value lines.

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

       -m|--minor minor
              Specify the minor number.

       -n|--noheadings
              Suppress the headings line when using columnar output.

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

       --notable
              When creating a device, don’t load any table.

       -o|--options
              Specify which fields to display.

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

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

       -u|--uuid
              Specify the uuid.

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

       --version
              Display the library and kernel driver version.

COMMANDS

       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
              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.

       export [device_name]
              Outputs  information in key/value format to be imported by other
              programs.

       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
              including 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   [--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,
              segments,  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,
              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.

       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 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.

       remove_all
              [-f|--force]
              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 processess 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.

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

       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.

       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 unflushed.

       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
              displayed.

       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 (thornber@sistina.com)

SEE ALSO

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