Provided by: lvm2_2.03.02-2ubuntu6_amd64 bug

NAME

       lvm — LVM2 tools

SYNOPSIS

       lvm [command|file]

DESCRIPTION

       The  Logical  Volume  Manager  (LVM)  provides  tools to create virtual block devices from
       physical devices.  Virtual devices may be easier to manage than physical devices, and  can
       have  capabilities  beyond  what  the physical devices provide themselves.  A Volume Group
       (VG) is a collection of one or more physical devices, each called a Physical Volume  (PV).
       A  Logical  Volume  (LV)  is  a  virtual  block  device  that can be used by the system or
       applications.  Each block of data in an LV is  stored  on  one  or  more  PV  in  the  VG,
       according to algorithms implemented by Device Mapper (DM) in the kernel.

       The  lvm  command, and other commands listed below, are the command-line tools for LVM.  A
       separate manual page describes each command in detail.

       If lvm is invoked with no arguments  it  presents  a  readline  prompt  (assuming  it  was
       compiled with readline support).  LVM commands may be entered interactively at this prompt
       with readline facilities including history and command name and option completion.   Refer
       to readline(3) for details.

       If  lvm  is invoked with argv[0] set to the name of a specific LVM command (for example by
       using a hard or soft link) it acts as that command.

       On invocation, lvm requires that only the standard  file  descriptors  stdin,  stdout  and
       stderr  are  available.   If  others  are  found,  they get closed and messages are issued
       warning about the leak.  This  warning  can  be  suppressed  by  setting  the  environment
       variable LVM_SUPPRESS_FD_WARNINGS.

       Where  commands  take  VG or LV names as arguments, the full path name is optional.  An LV
       called "lvol0" in a VG called "vg0" can be specified as "vg0/lvol0".  Where a list of  VGs
       is required but is left empty, a list of all VGs will be substituted.  Where a list of LVs
       is required but a VG is given, a list of all the LVs in that VG will be  substituted.   So
       lvdisplay  vg0  will  display  all the LVs in "vg0".  Tags can also be used - see --addtag
       below.

       One advantage of using the built-in shell is that configuration  information  gets  cached
       internally between commands.

       A  file  containing  a  simple  script  with one command per line can also be given on the
       command line.  The script can also be executed directly if the first line is  #!  followed
       by the absolute path of lvm.

       Additional  hyphens  within  option  names  are  ignored.   For  example,  --readonly  and
       --read-only are both accepted.

BUILT-IN COMMANDS

       The following commands are built into lvm without links  normally  being  created  in  the
       filesystem for them.

       config        The same as lvmconfig(8) below.
       devtypes      Display the recognised built-in block device types.
       dumpconfig    The same as lvmconfig(8) below.
       formats       Display recognised metadata formats.
       fullreport    Report  information about PVs, PV segments, VGs, LVs and LV segments, all at
                     once.
       help          Display the help text.
       lastlog       Display log report of last command run in LVM shell if command log reporting
                     is enabled.
       lvpoll        Complete lvmpolld operations (Internal command).
       segtypes      Display recognised Logical Volume segment types.
       systemid      Display any system ID currently set on this host.
       tags          Display any tags defined on this host.
       version       Display version information.

COMMANDS

       The following commands implement the core LVM functionality.

       pvchange      Change attributes of a Physical Volume.
       pvck          Check Physical Volume metadata.
       pvcreate      Initialize a disk or partition for use by LVM.
       pvdisplay     Display attributes of a Physical Volume.
       pvmove        Move Physical Extents.
       pvremove      Remove a Physical Volume.
       pvresize      Resize a disk or partition in use by LVM2.
       pvs           Report information about Physical Volumes.
       pvscan        Scan all disks for Physical Volumes.
       vgcfgbackup   Backup Volume Group descriptor area.
       vgcfgrestore  Restore Volume Group descriptor area.
       vgchange      Change attributes of a Volume Group.
       vgck          Check Volume Group metadata.
       vgconvert     Convert Volume Group metadata format.
       vgcreate      Create a Volume Group.
       vgdisplay     Display attributes of Volume Groups.
       vgexport      Make volume Groups unknown to the system.
       vgextend      Add Physical Volumes to a Volume Group.
       vgimport      Make exported Volume Groups known to the system.
       vgimportclone Import and rename duplicated Volume Group (e.g. a hardware snapshot).
       vgmerge       Merge two Volume Groups.
       vgmknodes     Recreate Volume Group directory and Logical Volume special files
       vgreduce      Reduce a Volume Group by removing one or more Physical Volumes.
       vgremove      Remove a Volume Group.
       vgrename      Rename a Volume Group.
       vgs           Report information about Volume Groups.
       vgscan        Scan all disks for Volume Groups.
       vgsplit       Split  a  Volume  Group into two, moving any logical volumes from one Volume
                     Group to another by moving entire Physical Volumes.
       lvchange      Change attributes of a Logical Volume.
       lvconvert     Convert a Logical Volume from linear to mirror or snapshot.
       lvcreate      Create a Logical Volume in an existing Volume Group.
       lvdisplay     Display attributes of a Logical Volume.
       lvextend      Extend the size of a Logical Volume.
       lvmconfig     Display the configuration information  after  loading  lvm.conf(5)  and  any
                     other configuration files.
       lvmdiskscan   Scan for all devices visible to LVM2.
       lvmdump       Create lvm2 information dumps for diagnostic purposes.
       lvreduce      Reduce the size of a Logical Volume.
       lvremove      Remove a Logical Volume.
       lvrename      Rename a Logical Volume.
       lvresize      Resize a Logical Volume.
       lvs           Report information about Logical Volumes.
       lvscan        Scan (all disks) for Logical Volumes.

       The  following  LVM1  commands  are  not  implemented in LVM2: lvmchange, lvmsadc, lvmsar,
       pvdata.  For performance metrics, use dmstats(8) or to manipulate the kernel device-mapper
       driver used by LVM2 directly, use dmsetup(8).

VALID NAMES

       The valid characters for VG and LV names are: a-z A-Z 0-9 + _ . -

       VG  names  cannot  begin  with  a  hyphen.   The name of a new LV also cannot begin with a
       hyphen.  However, if the configuration setting metadata/record_lvs_history is enabled then
       an  LV  name  with a hyphen as a prefix indicates that, although the LV was removed, it is
       still being tracked because it forms part of the history of at least one LV that is  still
       present.  This helps to record the ancestry of thin snapshots even after some links in the
       chain have been removed.  A reference to the historical LV 'lvol1' in VG 'vg00'  would  be
       'vg00/\-lvol1'  or  just  '-lvol1'  if  the  VG  is already set.  (The latter form must be
       preceded by '--'  to  terminate  command  line  option  processing  before  reaching  this
       argument.)

       There are also various reserved names that are used internally by lvm that can not be used
       as LV or VG names. A VG cannot be called anything that exists in  /dev/  at  the  time  of
       creation,  nor can it be called '.' or '..'.  An LV cannot be called '.', '..', 'snapshot'
       or 'pvmove'.  The LV name may also not contain any of  the  following  strings:  '_cdata',
       '_cmeta',   '_corig',  '_mlog',  '_mimage',  '_pmspare',  '_rimage',  '_rmeta',  '_tdata',
       '_tmeta' or '_vorigin'.  A directory bearing the name of  each  Volume  Group  is  created
       under  /dev  when any of its Logical Volumes are activated.  Each active Logical Volume is
       accessible from this directory as a symbolic link leading to  a  device  node.   Links  or
       nodes  in  /dev/mapper  are  intended  only  for  internal  use and the precise format and
       escaping might change between releases and  distributions.   Other  software  and  scripts
       should  use  the  /dev/VolumeGroupName/LogicalVolumeName  format  to  reduce the chance of
       needing amendment when the software is updated.  Should you need to process the node names
       in  /dev/mapper,  you  may  use  dmsetup splitname to separate out the original VG, LV and
       internal layer names.

UNIQUE NAMES

       VG names should be unique.  vgcreate will produce  an  error  if  the  specified  VG  name
       matches  an  existing VG name.  However, there are cases where different VGs with the same
       name can appear to LVM, e.g. after moving disks or changing filters.

       When VGs with the same name exist, commands operating on all VGs will include all  of  the
       VGs  with  the  same name.  If the ambiguous VG name is specified on the command line, the
       command will produce an error.   The  error  states  that  multiple  VGs  exist  with  the
       specified  name.   To  process  one of the VGs specifically, the --select option should be
       used with the UUID of the intended VG: '--select vg_uuid=<uuid>'.

       An exception is if all  but  one  of  the  VGs  with  the  shared  name  is  foreign  (see
       lvmsystemid(7).)   In  this  case,  the  one  VG  that is not foreign is assumed to be the
       intended VG and is processed.

       LV names are unique within a VG.  The name of an historical LV cannot be reused until  the
       historical LV has itself been removed or renamed.

ALLOCATION

       When  an operation needs to allocate Physical Extents for one or more Logical Volumes, the
       tools proceed as follows:

       First of all, they generate the complete set of unallocated Physical Extents in the Volume
       Group.   If  any  ranges  of Physical Extents are supplied at the end of the command line,
       only unallocated Physical Extents within those ranges on the  specified  Physical  Volumes
       are considered.

       Then  they  try  each  allocation  policy  in  turn,  starting  with  the strictest policy
       (contiguous) and ending with the allocation policy specified using --alloc or set  as  the
       default  for  the  particular  Logical Volume or Volume Group concerned.  For each policy,
       working from the lowest-numbered Logical Extent of the empty  Logical  Volume  space  that
       needs  to be filled, they allocate as much space as possible according to the restrictions
       imposed by the policy.  If more space is needed, they move on to the next policy.

       The restrictions are as follows:

       Contiguous requires that the physical location of any Logical Extent that is not the first
       Logical  Extent  of  a  Logical Volume is adjacent to the physical location of the Logical
       Extent immediately preceding it.

       Cling requires that the Physical Volume used for any Logical Extent  to  be  added  to  an
       existing  Logical  Volume is already in use by at least one Logical Extent earlier in that
       Logical Volume.  If the configuration parameter allocation/cling_tag_list is defined, then
       two  Physical Volumes are considered to match if any of the listed tags is present on both
       Physical Volumes.  This allows groups of Physical Volumes with similar properties (such as
       their physical location) to be tagged and treated as equivalent for allocation purposes.

       When  a  Logical  Volume  is  striped  or  mirrored,  the  above  restrictions are applied
       independently to each stripe or mirror image (leg) that needs space.

       Normal will not choose a Physical Extent that shares the same Physical Volume as a Logical
       Extent  already  allocated to a parallel Logical Volume (i.e. a different stripe or mirror
       image/leg) at the same offset within that parallel Logical Volume.

       When allocating a mirror log at the same time as Logical Volumes to hold the mirror  data,
       Normal  will  first try to select different Physical Volumes for the log and the data.  If
       that's not  possible  and  the  allocation/mirror_logs_require_separate_pvs  configuration
       parameter is set to 0, it will then allow the log to share Physical Volume(s) with part of
       the data.

       When allocating thin pool metadata, similar considerations to those of a mirror log in the
       last       paragraph       apply       based       on      the      value      of      the
       allocation/thin_pool_metadata_require_separate_pvs configuration parameter.

       If you rely upon any layout behaviour beyond that documented here, be aware that it  might
       change in future versions of the code.

       For  example,  if  you  supply on the command line two empty Physical Volumes that have an
       identical number of free Physical Extents  available  for  allocation,  the  current  code
       considers  using each of them in the order they are listed, but there is no guarantee that
       future releases will maintain that property.  If it is  important  to  obtain  a  specific
       layout  for a particular Logical Volume, then you should build it up through a sequence of
       lvcreate(8) and lvconvert(8) steps such that the restrictions described above  applied  to
       each step leave the tools no discretion over the layout.

       To  view  the  way  the  allocation process currently works in any specific case, read the
       debug logging output, for example by adding -vvvv to a command.

LOGICAL VOLUME TYPES

       Some logical volume types are simple to create and can be done with a  single  lvcreate(8)
       command.   The  linear  and  striped  logical  volume types are an example of this.  Other
       logical volume types may require more than one command to create.  The cache (lvmcache(7))
       and thin provisioning (lvmthin(7)) types are examples of this.

DIAGNOSTICS

       All  tools  return  a status code of zero on success or non-zero on failure.  The non-zero
       codes distinguish only between the broad categories  of  unrecognised  commands,  problems
       processing the command line arguments and any other failures.  As LVM remains under active
       development, the code used in a  specific  case  occasionally  changes  between  releases.
       Message text may also change.

ENVIRONMENT VARIABLES

       HOME   Directory containing .lvm_history if the internal readline shell is invoked.

       LVM_OUT_FD
              File descriptor to use for common output from LVM commands.

       LVM_ERR_FD
              File descriptor to use for error output from LVM commands.

       LVM_REPORT_FD
              File descriptor to use for report output from LVM commands.

       LVM_COMMAND_PROFILE
              Name  of default command profile to use for LVM commands. This profile is overriden
              by direct use of --commandprofile command line option.

       LVM_RUN_BY_DMEVENTD
              This variable is normally set by dmeventd plugin  to  inform  lvm2  command  it  is
              running  from dmeventd plugin so lvm2 takes some extra action to avoid comunication
              and deadlocks with dmeventd.

       LVM_SYSTEM_DIR
              Directory  containing  lvm.conf(5)  and  other  LVM  system  files.   Defaults   to
              "/etc/lvm".

       LVM_SUPPRESS_FD_WARNINGS
              Suppress warnings about unexpected file descriptors passed into LVM.

       LVM_VG_NAME
              The  Volume  Group  name that is assumed for any reference to a Logical Volume that
              doesn't specify a path.  Not set by default.

       LVM_LVMPOLLD_PIDFILE
              Path to the file that stores the lvmpolld process ID.

       LVM_LVMPOLLD_SOCKET
              Path to the socket used to communicate with lvmpolld..

       LVM_LOG_FILE_EPOCH
              A string of up to 32 letters appended to the  log  filename  and  followed  by  the
              process  ID  and  a startup timestamp using this format string "_%s_%d_%llu".  When
              set, each process logs to a separate file.

       LVM_LOG_FILE_MAX_LINES
              If more than this number of lines are sent  to  the  log  file,  the  command  gets
              aborted.  Automated tests use this to terminate looping commands.

       LVM_EXPECTED_EXIT_STATUS
              The  status  anticipated  when  the  process  exits.   Use ">N" to match any status
              greater than N.  If the actual exit status matches and a log file got produced,  it
              is   deleted.    LVM_LOG_FILE_EPOCH  and  LVM_EXPECTED_EXIT_STATUS  together  allow
              automated test scripts to discard uninteresting log data.

       LVM_SUPPRESS_LOCKING_FAILURE_MESSAGES
              Used to suppress warning messages when  the  configured  locking  is  known  to  be
              unavailable.

       DM_ABORT_ON_INTERNAL_ERRORS
              Abort processing if the code detects a non-fatal internal error.

       DM_DISABLE_UDEV
              Avoid interaction with udev.  LVM will manage the relevant nodes in /dev directly.

       DM_DEBUG_WITH_LINE_NUMBERS
              Prepends source file name and code line number with libdm debugging.

FILES

       /etc/lvm/lvm.conf
       $HOME/.lvm_history

SEE ALSO

       lvm(8) lvm.conf(5) lvmconfig(8)

       pvchange(8)  pvck(8)  pvcreate(8)  pvdisplay(8)  pvmove(8)  pvremove(8) pvresize(8) pvs(8)
       pvscan(8)

       vgcfgbackup(8) vgcfgrestore(8) vgchange(8) vgck(8) vgcreate(8)  vgconvert(8)  vgdisplay(8)
       vgexport(8)  vgextend(8)  vgimport(8) vgimportclone(8) vgmerge(8) vgmknodes(8) vgreduce(8)
       vgremove(8) vgrename(8) vgs(8) vgscan(8) vgsplit(8)

       lvcreate(8) lvchange(8)  lvconvert(8)  lvdisplay(8)  lvextend(8)  lvreduce(8)  lvremove(8)
       lvrename(8) lvresize(8) lvs(8) lvscan(8)

       lvm-fullreport(8) lvm-lvpoll(8) lvm2-activation-generator(8) blkdeactivate(8) lvmdump(8)

       dmeventd(8) lvmpolld(8) lvmlockd(8) lvmlockctl(8) cmirrord(8) lvmdbusd(8)

       lvmsystemid(7) lvmreport(7) lvmraid(7) lvmthin(7) lvmcache(7)

       dmsetup(8), dmstats(8), readline(3)