lvm man page on ElementaryOS

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LVM(8)									LVM(8)

NAME
       lvm - LVM2 tools

SYNOPSIS
       lvm [command | file]

DESCRIPTION
       lvm  provides  the command-line tools for LVM2.	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  com‐
       mand  (for  example  by using a hard or soft link) it acts as that com‐
       mand.

       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.

       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  substi‐
       tuted.	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	infor‐
       mation 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.

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

       dumpconfig — Display the configuration information after
	      loading lvm.conf(5) and any other configuration files.

       formats — Display recognised metadata formats.

       help — Display the help text.

       pvdata — Not implemented in LVM2.

       segtypes — Display recognised Logical Volume segment types.

       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 hard‐
       ware 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 and rebuild caches.

       vgsplit — Split a Volume Group into two, moving any logical
	      volumes from one Volume Group to another by moving entire Physi‐
	      cal 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.

       lvmchange — Change attributes of the Logical Volume Manager.

       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 commands are not implemented in LVM2 but might be in the
       future: lvmsadc, lvmsar, pvdata.

OPTIONS
       The following options are available for many of the commands.  They are
       implemented  generically	 and  documented  here rather than repeated on
       individual manual pages.

       -h, --help
	      Display the help text.

       --version
	      Display version information.

       -v, --verbose
	      Set verbose level. Repeat from 1 to  3  times  to	 increase  the
	      detail  of messages sent to stdout and stderr.  Overrides config
	      file setting.

       -d, --debug
	      Set debug level. Repeat from 1 to 6 times to increase the detail
	      of  messages sent to the log file and/or syslog (if configured).
	      Overrides config file setting.

       -q, --quiet
	      Suppress output and log messages.	 Overrides -d and -v.

       -t, --test
	      Run in test mode. Commands will not update  metadata.   This  is
	      implemented  by  disabling all metadata writing but nevertheless
	      returning success to the calling function.   This	 may  lead  to
	      unusual  error  messages	in  multi-stage	 operations  if a tool
	      relies on reading back metadata  it  believes  has  changed  but
	      hasn't.

       --driverloaded {y|n}
	      Whether  or  not	the device-mapper kernel driver is loaded.  If
	      you set this to n, no  attempt  will  be	made  to  contact  the
	      driver.

       -A, --autobackup {y|n}
	      Whether  or  not	to  metadata should be backed up automatically
	      after a change.  You are strongly advised not to	disable	 this!
	      See vgcfgbackup(8).

       -P, --partial
	      When set, the tools will do their best to provide access to Vol‐
	      ume Groups that are only partially available (one or more Physi‐
	      cal  Volumes  belonging to the Volume Group are missing from the
	      system).	Where part of a logical volume is missing,  /dev/ioer‐
	      ror  will	 be  substituted,  and you could use dmsetup(8) to set
	      this up to return I/O errors when accessed, or create  it	 as  a
	      large  block  device of nulls.  Metadata may not be changed with
	      this option. To insert a replacement Physical Volume of the same
	      or large size use pvcreate -u to set the uuid to match the orig‐
	      inal followed by vgcfgrestore(8).

       -M, --metadatatype Type
	      Specifies which type of on-disk metadata to use, such as lvm1 or
	      lvm2,  which  can	 be  abbreviated  to 1 or 2 respectively.  The
	      default (lvm2) can be changed by setting format  in  the	global
	      section of the config file.

       --ignorelockingfailure
	      This lets you proceed with read-only metadata operations such as
	      lvchange -ay and vgchange -ay even if the locking module	fails.
	      One  use	for this is in a system init script if the lock direc‐
	      tory is mounted read-only when the script runs.

       --addtag Tag
	      Add the tag Tag to a PV, VG or LV.  Supply this argument	multi‐
	      ple  times  to  add  more than one tag at once.  A tag is a word
	      that can be  used	 to  group  LVM2  objects  of  the  same  type
	      together.	 Tags can be given on the command line in place of PV,
	      VG or LV arguments.  Tags should be prefixed  with  @  to	 avoid
	      ambiguity.   Each	 tag  is  expanded  by	replacing  it with all
	      objects possessing that tag which are of the  type  expected  by
	      its  position  on	 the  command line.  PVs can only possess tags
	      while they are part of a Volume Group: PV tags are discarded  if
	      the  PV  is  removed  from the VG.  As an example, you could tag
	      some LVs as database and others as userdata  and	then  activate
	      the database ones with lvchange -ay @database.  Objects can pos‐
	      sess multiple tags simultaneously.  Only the new	LVM2  metadata
	      format  supports tagging: objects using the LVM1 metadata format
	      cannot be tagged because the on-disk format does not support it.
	      Characters  allowed  in  tags are: A-Z a-z 0-9 _ + . - and as of
	      version 2.02.78 the following characters are also accepted: /  =
	      ! : # &

       --deltag Tag
	      Delete the tag Tag from a PV, VG or LV, if it's present.	Supply
	      this argument multiple times to remove  more  than  one  tag  at
	      once.

       --alloc AllocationPolicy
	      The  allocation  policy  to use: contiguous, cling, normal, any‐
	      where or inherit.	 When a command	 needs	to  allocate  Physical
	      Extents  from  the  Volume Group, the allocation policy controls
	      how they are chosen.  Each Volume Group and Logical  Volume  has
	      an allocation policy defined.  The default for a Volume Group is
	      normal which applies common-sense rules such as not placing par‐
	      allel  stripes  on  the same Physical Volume.  The default for a
	      Logical Volume is inherit which applies the same policy  as  for
	      the   Volume   Group.   These  policies  can  be	changed	 using
	      lvchange(8) and vgchange(8) or overridden on the command line of
	      any  command  that  performs  allocation.	 The contiguous policy
	      requires that new Physical Extents be placed adjacent to	exist‐
	      ing  Physical  Extents.	The  cling  policy places new Physical
	      Extents on the same Physical Volume as existing Physical Extents
	      in  the  same stripe of the Logical Volume.  If there are suffi‐
	      cient free Physical Extents to satisfy an allocation request but
	      normal  doesn't  use  them, anywhere will - even if that reduces
	      performance by placing two stripes on the same Physical Volume.

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

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

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

       VG and LV names cannot begin with a hyphen.   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 '..'.	A LV cannot be
       called '.' '..' 'snapshot' or 'pvmove'. The LV name may also  not  con‐
       tain the strings '_mlog', '_mimage', '_rimage', '_tdata', '_tmeta'.

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 con‐
       sidered.

       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	 Logi‐
       cal  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 configura‐
       tion 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 Vol‐
       ume (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	Physi‐
       cal  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 param‐
       eter.

       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  Vol‐
       umes  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.

DIAGNOSTICS
       All tools return a status code of zero on success or non-zero on	 fail‐
       ure.

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

SEE ALSO
       clvmd(8),  lvchange(8),	lvcreate(8),  lvdisplay(8),  lvextend(8), lvm‐
       change(8), lvmdiskscan(8), lvreduce(8), lvremove(8), lvrename(8), lvre‐
       size(8),	 lvs(8),  lvscan(8), pvchange(8), pvck(8), pvcreate(8), pvdis‐
       play(8), pvmove(8),  pvremove(8),  pvs(8),  pvscan(8),  vgcfgbackup(8),
       vgchange(8),  vgck(8),  vgconvert(8),  vgcreate(8), vgdisplay(8), vgex‐
       tend(8), vgimport(8), vgimportclone(8), vgmerge(8), vgmknodes(8), vgre‐
       duce(8), vgremove(8), vgrename(8), vgs(8), vgscan(8), vgsplit(8), read‐
       line(3), lvm.conf(5)

Sistina Software UK    LVM TOOLS 2.02.98(2) (2012-10-15)		LVM(8)
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