|
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)
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).
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).
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.
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 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.
/etc/lvm/lvm.conf
$HOME/.lvm_history
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)
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 2018-02-02. (At that time,
the date of the most recent commit that was found in the repository
was 2018-02-01.) 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 2.02.178(2)-git (2017-12-18) LVM(8)
Pages that refer to this page: lvm.conf(5), lvmcache(7), lvmraid(7), lvmreport(7), lvmsystemid(7), lvmthin(7), blkdeactivate(8), clvmd(8), cmirrord(8), fsadm(8), lvchange(8), lvconvert(8), lvcreate(8), lvdisplay(8), lvextend(8), lvm(8), lvmconf(8), lvmconfig(8), lvmdbusd(8), lvmdiskscan(8), lvmdump(8), lvmetad(8), lvm-fullreport(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), vgmerge(8), vgmknodes(8), vgreduce(8), vgremove(8), vgrename(8), vgs(8), vgscan(8), vgsplit(8), xfs_freeze(8), xfs_growfs(8)
|
HTML rendering created 2018-02-02 by Michael Kerrisk, author of The Linux Programming Interface, maintainer of the Linux man-pages project. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH.
|
|