Provided by: lvm2_2.02.98-6ubuntu2_amd64 
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 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.
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.
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 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.
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 Volume Groups that are only partially
available (one or more Physical Volumes belonging to the Volume Group are missing from the
system). Where part of a logical volume is missing, /dev/ioerror 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 original
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
directory is mounted read-only when the script runs.
--addtag Tag
Add the tag Tag to a PV, VG or LV. Supply this argument multiple 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 possess 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, anywhere 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 parallel 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 existing 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 sufficient 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 contain 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 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.
DIAGNOSTICS
All tools return a status code of zero on success or non-zero on failure.
FILES
/etc/lvm/lvm.conf
$HOME/.lvm_history
SEE ALSO
clvmd(8), lvchange(8), lvcreate(8), lvdisplay(8), lvextend(8), lvmchange(8), lvmdiskscan(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), pvs(8), pvscan(8), vgcfgbackup(8), vgchange(8), vgck(8),
vgconvert(8), vgcreate(8), vgdisplay(8), vgextend(8), vgimport(8), vgimportclone(8), vgmerge(8),
vgmknodes(8), vgreduce(8), vgremove(8), vgrename(8), vgs(8), vgscan(8), vgsplit(8), readline(3),
lvm.conf(5)
Sistina Software UK LVM TOOLS 2.02.98(2) (2012-10-15) LVM(8)