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NAME | SYNOPSIS | DESCRIPTION | BUILT-IN COMMANDS | COMMANDS | VALID NAMES | UNIQUE NAMES | ALLOCATION | LOGICAL VOLUME TYPES | DIAGNOSTICS | ENVIRONMENT VARIABLES | FILES | SEE ALSO | COLOPHON |
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LVM(8) System Manager's Manual LVM(8)
lvm — LVM2 tools
lvm [command|file]
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.
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.
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).
vgimportdevices
Add PVs from a VG to the devices file.
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.
lvmdevices
Manage the devices file.
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).
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', '_iorig',
'_mimage', '_mlog', '_pmspare', '_rimage', '_rmeta', '_tdata',
'_tmeta', '_vdata', '_vorigin' or '_wcorig'. 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.
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.
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.
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.
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.
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 overridden 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 communication 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_SUPPRESS_SYSLOG
Suppress contacting syslog.
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.
/etc/lvm/lvm.conf
$HOME/.lvm_history
lvm(8), lvm.conf(5), lvmconfig(8), lvmdevices(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), vgimportdevices(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), blkdeactivate(8), lvmdump(8),
dmeventd(8), lvmpolld(8), lvmlockd(8), lvmlockctl(8),
cmirrord(8), lvmdbusd(8), fsadm(8),
lvmsystemid(7), lvmreport(7), lvmcache(7), lvmraid(7),
lvmthin(7), lvmvdo(7), lvmautoactivation(7),
dmsetup(8), dmstats(8), readline(3)
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, see ⟨https://github.com/lvmteam/lvm2/issues⟩.
This page was obtained from the project's upstream Git repository
⟨git://sourceware.org/git/lvm2.git⟩ on 2024-06-14. (At that
time, the date of the most recent commit that was found in the
repository was 2024-06-11.) 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 2.03.25(2)-git (2024-05-16) LVM(8)
Pages that refer to this page: lvm.conf(5), lvmcache(7), lvmraid(7), lvmreport(7), lvmsystemid(7), lvmthin(7), lvmvdo(7), blkdeactivate(8), cmirrord(8), dmeventd(8), fsadm(8), lvchange(8), lvconvert(8), lvcreate(8), lvdisplay(8), lvextend(8), lvm(8), lvmconfig(8), lvmdbusd(8), lvmdevices(8), lvmdiskscan(8), lvmdump(8), lvm-fullreport(8), lvm_import_vdo(8), lvmlockctl(8), lvmlockd(8), lvm-lvpoll(8), lvmpolld(8), lvmsadc(8), lvmsar(8), lvreduce(8), lvremove(8), lvrename(8), lvresize(8), lvs(8), lvscan(8), pvchange(8), pvck(8), pvcreate(8), pvdisplay(8), pvmove(8), pvremove(8), pvresize(8), pvs(8), pvscan(8), resize2fs(8), vgcfgbackup(8), vgcfgrestore(8), vgchange(8), vgck(8), vgconvert(8), vgcreate(8), vgdisplay(8), vgexport(8), vgextend(8), vgimport(8), vgimportclone(8), vgimportdevices(8), vgmerge(8), vgmknodes(8), vgreduce(8), vgremove(8), vgrename(8), vgs(8), vgscan(8), vgsplit(8), xfs_freeze(8), xfs_growfs(8), xfs_info(8)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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