NAME | SYNOPSIS | DESCRIPTION | BUILT-IN COMMANDS | COMMANDS | VALID NAMES | UNIQUE NAMES | ALLOCATION | LOGICAL VOLUME TYPES | DIAGNOSTICS | ENVIRONMENT VARIABLES | FILES | SEE ALSO | COLOPHON

LVM(8)                     System Manager's Manual                    LVM(8)

NAME         top

       lvm — LVM2 tools

SYNOPSIS         top

       lvm [command|file]

DESCRIPTION         top

       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         top

       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         top

       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 and rebuild caches.
       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         top

       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         top

       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         top

       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         top

       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         top

       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         top

       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_LVMETAD_PIDFILE
              Path to the file that stores the lvmetad process ID.

       LVM_LVMETAD_SOCKET
              Path to the socket used to communicate with lvmetad.

       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.

FILES         top

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

SEE ALSO         top

       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) lvmetad(8) lvmpolld(8) lvmlockd(8) lvmlockctl(8) clvmd(8)
       cmirrord(8) lvmdbusd(8)

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

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

COLOPHON         top

       This page is part of the lvm2 (Logical Volume Manager 2) project.
       Information about the project can be found at 
       ⟨http://www.sourceware.org/lvm2/⟩.  If you have a bug report for this
       manual page, send it to linux-lvm@redhat.com.  This page was obtained
       from the project's upstream Git repository 
       ⟨git://sourceware.org/git/lvm2.git⟩ on 2017-09-15.  If you discover
       any rendering problems in this HTML version of the page, or you
       believe there is a better or more up-to-date source for the page, or
       you have corrections or improvements to the information in this
       COLOPHON (which is not part of the original manual page), send a mail
       to man-pages@man7.org

Red Hat, Inc.      LVM TOOLS 2.02.175(2)-git (2017-09-13)             LVM(8)

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