Ubuntu Manpage: lvm — LVM2 tools

Provided by: lvm2_2.02.133-1ubuntu10_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. 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.

BUILT-IN COMMANDS

       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.
       help          Display the help text.
       lvpoll        Complete lvmpolld operations (Internal command).
       pvdata        Not implemented in LVM2.
       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

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.
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 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.

Additional hyphens within option names are ignored. For example, --readonly and --read-only are both
accepted.

-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. Repeat once to also suppress any prompts
with answer 'no'.

--yes
Don't prompt for confirmation interactively but instead always assume the answer is 'yes'. Take
great care if you use this!

-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).

-S|--select Selection
For reporting commands, display only rows that match Selection criteria. All rows are displayed
with the additional "selected" column (-o selected) showing 1 if the row matches the Selection and
0 otherwise. For non-reporting commands which process LVM entities, the selection can be used to
match items to process. See SELECTION CRITERIA section of this man page for more information about
the way the selection criteria are constructed.

-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 lvm.conf(5).

--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.

--ignoreskippedcluster
Use to avoid exiting with an non-zero status code if the command is run without clustered locking
and some clustered Volume Groups have to be skipped over.

--readonly
Run the command in a special read-only mode which will read on-disk metadata without needing to
take any locks. This can be used to peek inside metadata used by a virtual machine image while
the virtual machine is running. It can also be used to peek inside the metadata of clustered
Volume Groups when clustered locking is not configured or running. No attempt will be made to
communicate with the device-mapper kernel driver, so this option is unable to report whether or
not Logical Volumes are actually in use.

--foreign
Cause the command to access foreign VGs, that would otherwise be skipped. It can be used to
report or display a VG that is owned by another host. This option can cause a command to perform
poorly because lvmetad caching is not used and metadata is read from disks.

--shared
Cause the command to access shared VGs, that would otherwise be skipped when lvmlockd is not being
used. It can be used to report or display a lockd VG without locking.

--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 {anywhere|contiguous|cling|inherit|normal}
Selects the allocation policy when a command needs to allocate Physical Extents from the Volume
Group. 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.

--commandprofile ProfileName
Selects the command configuration profile to use when processing an LVM command. See also
lvm.conf(5) for more information about command profile config and the way it fits with other LVM
configuration methods. Using --commandprofile option overrides any command profile specified via
LVM_COMMAND_PROFILE environment variable.

--metadataprofile ProfileName
Selects the metadata configuration profile to use when processing an LVM command. When using
metadata profile during Volume Group or Logical Volume creation, the metadata profile name is
saved in metadata. When such Volume Group or Logical Volume is processed next time, the metadata
profile is automatically applied and the use of --metadataprofile option is not necessary. See
also lvm.conf(5) for more information about metadata profile config and the way it fits with other
LVM configuration methods.

--profile ProfileName
A short form of --metadataprofile for vgcreate, lvcreate, vgchange and lvchange command and a
short form of --commandprofile for any other command (with the exception of lvmconfig command
where the --profile has special meaning, see lvmconfig(8) for more information).

--config ConfigurationString
Uses the ConfigurationString as direct string representation of the configuration to override the
existing configuration. The ConfigurationString is of exactly the same format as used in any LVM
configuration file. See lvm.conf(5) for more information about direct config override on command
line and the way it fits with other LVM configuration methods.

VALID NAMES

       The valid characters for VG and LV names are: 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 '..'.  An  LV  cannot  be  called  '.',  '..',
       'snapshot'  or  'pvmove'.   The  LV  name  may also not contain any of the following strings: 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.

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.

LOGICAL VOLUME TYPES

       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.

SELECTION CRITERIA

       The  selection criteria are a set of statements combined by logical and grouping operators. The statement
       consists of column name for which a set of valid  values  is  defined  using  comparison  operators.  For
       complete  list  of  column names (fields) that can be used in selection, see the output of <lvm reporting
       command> -S help.

   Comparison operators (cmp_op)
       =~     Matching regular expression.
       !~     Not matching regular expression.
       =      Equal to.
       !=     Not equal to.
       >=     Greater than or equal to.
       >      Greater than
       <=     Less than or equal to.
       <      Less than.

   Binary logical operators (cmp_log)
       &&     All fields must match
       ,      All fields must match
       ||     At least one field must match
       #      At least one field must match

   Unary logical operators
       !      Logical negation

   Grouping operators
       (      Left parenthesis
       )      Right parenthesis
       [      List start
       ]      List end
       {      List subset start
       }      List subset end

   Informal grammar specification

       STATEMENT = column cmp_op VALUE | STATEMENT log_op STATEMENT | (STATEMENT) | !(STATEMENT)

       VALUE = [VALUE log_op VALUE]
              For list-based types: string list. Matches strictly.  The log_op must always be of one type within
              the whole list value.

       VALUE = {VALUE log_op VALUE}
              For list-based types: string list. Matches a subset.  The log_op must always be of one type within
              the whole list value.

       VALUE = value
              For scalar types: number (integer), size (floating point number with size  unit  suffix),  percent
              (floating point number with or without % suffix), string.

DIAGNOSTICS

       All tools return a status code of zero on success or non-zero on failure.

ENVIRONMENT VARIABLES

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

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_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
timestamp. When set, each process logs to a separate file.

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

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