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       lvm.conf - Configuration file for LVM2




       lvm.conf  is  loaded  during the initialisation phase of lvm (8).  This
       file can in turn lead to other files being loaded -  settings  read  in
       later  override  earlier settings.  File timestamps are checked between
       commands and if any have changed, all the files are reloaded.

       Use lvm dumpconfig to check what settings are in use.


       This section describes the configuration file syntax.

       Whitespace is  not  significant  unless  it  is  within  quotes.   This
       provides  a  wide  choice  of  acceptable indentation styles.  Comments
       begin with # and continue to the end of the line.  They are treated  as

       Here is an informal grammar:

       file = value*
              A configuration file consists of a set of values.

       value = section | assignment
              A value can either be a new section, or an assignment.

       section = identifier{value*}’
              A section is groups associated values together.
              It is denoted by a name and delimited by curly brackets.
              e.g. backup {

       assignment = identifier=(array | type)
              An assignment associates a type with an identifier.
              e.g. max_archives = 42

       array =[(type,)* type]|[’ ’]’
              Inhomogeneous arrays are supported.
              Elements must be separated by commas.
              An empty array is acceptable.

       type = integer | float | string
              integer = [0-9]*
              float = [0-9]*.[0-9]*
              string =".*"’

              Strings must be enclosed in double quotes.


       The sections that may be present in the file are:

       devices — Device settings

              dir  —  Directory  in which to create volume group device nodes.
              Defaults to "/dev".  Commands also accept this as  a  prefix  on
              volume group names.

              scan  — List of directories to scan recursively for LVM physical
              volumes.  Devices in directories outside this hierarchy will  be
              ignored.  Defaults to "/dev".

              preferred_names  — List of patterns compared in turn against all
              the pathnames referencing the same  device  in  in  the  scanned
              directories.   The pathname that matches the earliest pattern in
              the list is the one used in  any  output.   As  an  example,  if
              device-mapper  multipathing  is  used, the following will select
              multipath device names:
              devices { preferred_names = [ "^/dev/mapper/mpath" ] }

              filter — List of patterns to apply to devices found by  a  scan.
              Patterns  are regular expressions delimited by any character and
              preceded by a (for accept) or  r  (for  reject).   The  list  is
              traversed  in order, and the first regex that matches determines
              if the device will be accepted or rejected  (ignored).   Devices
              that  don’t  match  any  patterns  are  accepted. If you want to
              reject patterns that don’t match, end the list with "r/.*/".  If
              there are several names for the same device (e.g. symbolic links
              in /dev), if any name matches  any  a  pattern,  the  device  is
              accepted;  otherwise  if  any  name  matches any r pattern it is
              rejected; otherwise it is accepted.  As an  example,  to  ignore
              /dev/cdrom you could use:
              devices { filter=["r|cdrom|"] }

              cache_dir — Persistent filter cache file directory.  Defaults to

              write_cache_state — Set to 0 to disable the writing out  of  the
              persistent filter cache file when lvm exits.  Defaults to 1.

              types  —  List  of  pairs  of additional acceptable block device
              types found in /proc/devices together  with  maximum  (non-zero)
              number  of  partitions (normally 16).  By default, LVM2 supports
              ide, sd, md, loop, dasd, dac960, nbd, ida, cciss, ubd,  ataraid,
              drbd,  power2,  i2o_block  and  iseries/vd.   Block devices with
              major numbers of different types are ignored by LVM2.   Example:
              types = ["fd", 16].  To create physical volumes on device-mapper
              volumes  created  outside  LVM2,  perhaps  encrypted  ones  from
              cryptsetup,  you’ll  need types = ["device-mapper", 16].  But if
              you do this, be careful to avoid  recursion  within  LVM2.   The
              figure  for number of partitions is not currently used in LVM2 -
              and might never be.

              sysfs_scan — If set to 1 and your kernel supports sysfs  and  it
              is  mounted,  sysfs will be used as a quick way of filtering out
              block devices that are not present.

              md_component_detection — If set to 1, LVM2 will  ignore  devices
              used  as components of software RAID (md) devices by looking for
              md superblocks. This doesn’t always work satisfactorily e.g.  if
              a  device  has  been  reused  without  wiping the md superblocks

              md_chunk_alignment — If set to  1,  and  a  Physical  Volume  is
              placed  directly  upon  an  md  device, LVM2 will align its data
              blocks with the md device’s stripe-width.

              data_alignment_detection — If set to 1, and your kernel provides
              topology information in sysfs for the Physical Volume, the start
              of data area will be aligned on a multiple of the âârequest  the
              device can perform without incurring a read-modify-write penalty
              (e.g.  MD’s  chunk  size).   optimal_io_size  is  the   device’s
              preferred  unit  of  receiving  I/O  (e.g.  MD’s  stripe width).
              minimum_io_size is used if optimal_io_size is undefined (0).  If
              both md_chunk_alignment and data_alignment_detection are enabled
              the result of data_alignment_detection is used.

              data_alignment — Default alignment (in KB) of start of data area
              when creating a new Physical Volume using the lvm2 format.  If a
              Physical Volume  is  placed  directly  upon  an  md  device  and
              md_chunk_alignment  or  data_alignment_detection is enabled this
              parameter is ignored.  Set to 0 to use the default alignment  of
              64KB or the page size, if larger.

              data_alignment_offset_detection  —  If set to 1, and your kernel
              provides topology information in sysfs for the Physical  Volume,
              the  start  of the aligned data area of the Physical Volume will
              be shifted by the alignment_offset exposed in sysfs.

              To see the location of the first Physical Extent of an  existing
              Physical Volume use pvs -o +pe_start .  It will be a multiple of
              the requested  data_alignment  plus  the  alignment_offset  from
              data_alignment_offset_detection  (if  enabled)  or  the pvcreate

       log — Default log settings

              file — Location of log file.  If this entry is not  present,  no
              log file is written.

              overwrite  — Set to 1 to overwrite the log file each time a tool
              is invoked.  By default tools append messages to the log file.

              level — Log level (0-9) of messages to write to the file.  9  is
              the most verbose; 0 should produce no output.

              verbose  —  Default  level  (0-3)  of messages sent to stdout or
              stderr.  3 is the most  verbose;  0  should  produce  the  least

              syslog  —  Set  to  1 (the default) to send log messages through
              syslog.  Turn off by setting to 0.  If you  set  to  an  integer
              greater  than one, this is used - unvalidated - as the facility.
              The default is LOG_USER.  See /usr/include/sys/syslog.h for safe
              facility values to use.  For example, LOG_LOCAL0 might be 128.

              indent  —  When  set  to  1  (the default) messages are indented
              according to their severity, two spaces per level.  Set to 0  to
              turn off indentation.

              command_names  —  When  set  to 1, the command name is used as a
              prefix for each message.  Default is 0 (off).

              prefix — Prefix used for all messages (after the command  name).
              Default is two spaces.

              activation  —  Set  to  1  to  log  messages  while  devices are
              suspended during activation.  Only set  this  temporarily  while
              debugging  a  problem  because  in  low  memory  situations this
              setting can cause your machine to lock up.

       backup — Configuration for metadata backups.

              archive_dir — Directory used for  automatic  metadata  archives.
              Backup  copies  of  former  metadata  for  each volume group are
              archived here.  Defaults to "/etc/lvm/archive".

              backup_dir — Directory used for automatic metadata  backups.   A
              single backup copy of the current metadata for each volume group
              is stored here.  Defaults to "/etc/lvm/backup".

              archive — Whether or not tools  automatically  archive  existing
              metadata  into archive_dir before making changes to it.  Default
              is 1  (automatic  archives  enabled).   Set  to  0  to  disable.
              Disabling   this  might  make  metadata  recovery  difficult  or
              impossible if something goes wrong.

              backup — Whether or not tools  make  an  automatic  backup  into
              backup_dir  after  changing  metadata.   Default is 1 (automatic
              backups enabled).  Set to 0 to disable.   Disabling  this  might
              make metadata recovery difficult or impossible if something goes

              retain_min — Minimum number of archives to  keep.   Defaults  to

              retain_days  —  Minimum  number  of  days to keep archive files.
              Defaults to 30.

       shell — LVM2 built-in readline shell settings

              history_size — Maximum number  of  lines  of  shell  history  to
              retain (default 100) in $HOME/.lvm_history

       global — Global settings

              test  —  If  set to 1, run tools in test mode i.e. no changes to
              the on-disk metadata will get made.  It’s equivalent  to  having
              the -t option on every command.

              activation  —  Set  to  0 to turn off all communication with the
              device-mapper driver.  Useful if you want to manipulate  logical
              volumes while device-mapper is not present in your kernel.

              proc — Mount point of proc filesystem.  Defaults to /proc.

              umask  —  File  creation  mask  for  any  files  and directories
              created.  Interpreted as octal  if  the  first  digit  is  zero.
              Defaults to 077.  Use 022 to allow other users to read the files
              by default.

              format — The default value of --metadatatype used  to  determine
              which  format  of  metadata  to  use  when creating new physical
              volumes and volume groups. lvm1 or lvm2.

              fallback_to_lvm1 — Set this to 1 if  you  need  to  be  able  to
              switch  between  2.4  kernels  using  LVM1 and kernels including
              device-mapper.  The LVM2 tools should be installed as normal and
              the  LVM1  tools  should  be  installed with a .lvm1 suffix e.g.
              vgscan.lvm1.  If  an  LVM2  tool  is  then  run  but  unable  to
              communicate with device-mapper, it will automatically invoke the
              equivalent LVM1 version of the tool.  Note that for  LVM1  tools
              to manipulate physical volumes and volume groups created by LVM2
              you must use --metadataformat lvm1 when creating them.

              library_dir — A directory searched for LVM2’s  shared  libraries
              ahead of the places dlopen (3) searches.

              format_libraries  —  A  list  of  shared  libraries to load that
              contain code to  process  different  formats  of  metadata.  For
              example,  is  needed  to  read  GFS  pool
              metadata if LVM2 was configured --with-pool=shared.

              locking_type — What type of locking to use.  1 is  the  default,
              which  use  flocks  on files in locking_dir (see below) to avoid
              conflicting LVM2  commands  running  concurrently  on  a  single
              machine.  0 disables locking and risks corrupting your metadata.
              If set to 2, the tools will load  the  external  locking_library
              (see   below).    If   the   tools   were   configured   --with-
              cluster=internal (the default) then  3  means  to  use  built-in
              cluster-wide  locking.   Type  4 enforces read-only metadata and
              forbids any operations that might want to  modify  Volume  Group
              metadata.   All  changes to logical volumes and their states are
              communicated using locks.

              wait_for_locks — When set to 1, the default, the tools wait if a
              lock  request  cannot  be satisfied immediately.  When set to 0,
              the operation is aborted instead.

              locking_dir — The  directory  LVM2  places  its  file  locks  if
              locking_type is set to 1.  The default is /var/lock/lvm.

              locking_library  —  The  name of the external locking library to
              load  if  locking_type  is   set   to   2.    The   default   is
       If  you  need  to write such a library,
              look at the lib/locking source code directory.

       tags — Host tag settings

              hosttags — If set to 1, create a host tag with the machine name.
              Setting  this to 0 does nothing, neither creating nor destroying
              any tag.  The machine name used is the nodename as  returned  by
              uname (2).

              Additional   host   tags  to  be  set  can  be  listed  here  as
              subsections.  The @ prefix for tags is optional.  Each of  these
              host  tag  subsections  can  contain  a  host_list array of host
              names. If any one of these  entries  matches  the  machine  name
              exactly  then the host tag gets defined on this particular host,
              otherwise it doesn’t.

              After lvm.conf has been processed, LVM2 works through each  host
              tag   that  has  been  defined  in  turn,  and  if  there  is  a
              configuration file called  lvm_<host_tag>.conf  it  attempts  to
              load  it.   Any  settings  read  in  override  settings found in
              earlier files.  Any additional host tags defined get appended to
              the   search   list,  so  in  turn  they  can  lead  to  further
              configuration files being  processed.   Use  lvm  dumpconfig  to
              check the result of config file processing.

              The  following  example always sets host tags tag1 and sets tag2
              on machines fs1 and fs2:

              tags { tag1 { } tag2 { host_list = [ "fs1", "fs2" ] } }

              These options are useful if you  are  replicating  configuration
              files around a cluster.  Use of hosttags = 1 means every machine
              can have static and identical local configuration files yet  use
              different  settings  and  activate  different logical volumes by
              default.  See also volume_list below and --addtag in lvm (8).

       activation — Settings affecting device-mapper activation

              missing_stripe_filler — When activating  an  incomplete  logical
              volume  in  partial  mode,  this option dictates how the missing
              data is replaced.  A value of "error" will cause  activation  to
              create  error  mappings  for the missing data, meaning that read
              access to missing portions of the  volume  will  result  in  I/O
              errors. You can instead also use a device path, and in that case
              this device will be used in place of missing  stripes.  However,
              note  that  using  anything  other than "error" with mirrored or
              snapshotted volumes is likely to result in data corruption.  For
              instructions  on  how  to  create  a  device that always returns
              zeros, see lvcreate (8).

              mirror_region_size — Unit size in KB for  copy  operations  when

              readahead  — Used when there is no readahead value stored in the
              volume group metadata.  Set to  none  to  disable  readahead  in
              these  circumstances  or auto to use the default value chosen by
              the kernel.

              reserved_memory, reserved_stack — How many  KB  to  reserve  for
              LVM2   to   use   while   logical  volumes  are  suspended.   If
              insufficient memory is reserved before suspension,  there  is  a
              risk of machine deadlock.

              process_priority  —  The  nice  value  to  use while devices are
              suspended.  This is set to  a  high  priority  so  that  logical
              volumes  are suspended (with I/O generated by other processes to
              those logical volumes getting queued) for the shortest  possible

              volume_list  —  This acts as a filter through which all requests
              to activate a logical volume on  this  machine  are  passed.   A
              logical  volume  is  only activated if it matches an item in the
              list.  Tags must be preceded by @ and are  checked  against  all
              tags defined in the logical volume and volume group metadata for
              a match.  @* is short-hand to check every tag set  on  the  host
              machine  (see tags above).  Logical volume and volume groups can
              also be included in the list by name e.g. vg00, vg00/lvol1.

       metadata — Advanced metadata settings

              pvmetadatacopies — When creating a  physical  volume  using  the
              LVM2  metadata  format,  this is the default number of copies of
              metadata to store on each physical volume.  Currently it can  be
              set  to  0, 1 or 2.  The default is 1.  If set to 2, one copy is
              placed at the beginning of the disk and the other is  placed  at
              the  end.   It  can  be  overridden  on  the  command  line with
              --metadatacopies.  If creating a  volume  group  with  just  one
              physical volume, it’s a good idea to have 2 copies.  If creating
              a large volume group with many physical volumes, you may  decide
              that  3 copies of the metadata is sufficient, i.e. setting it to
              1 on three of the physical volumes, and 0 on  the  rest.   Every
              volume  group  must contain at least one physical volume with at
              least 1 copy of  the  metadata  (unless  using  the  text  files
              described  below).  The disadvantage of having lots of copies is
              that every time the tools access the volume group, every copy of
              the  metadata has to be accessed, and this slows down the tools.

              pvmetadatasize — Approximate number of sectors to set aside  for
              each  copy  of the metadata. Volume groups with large numbers of
              physical  or  logical  volumes,  or  volumes  groups  containing
              complex logical volume structures will need additional space for
              their metadata.  The metadata  areas  are  treated  as  circular
              buffers,  so  unused space becomes filled with an archive of the
              most recent previous versions of the metadata.

              dirs — List of directories holding live copies of LVM2  metadata
              as  text  files.   These  directories  must  not  be  on logical
              volumes.   It  is  possible  to  use  LVM2  with  a  couple   of
              directories  here,  preferably on different (non-logical-volume)
              filesystems and with no other on-disk metadata, pvmetadatacopies
              =  0.  Alternatively these directories can be in addition to the
              on-disk metadata areas.  This feature  was  created  during  the
              development of the LVM2 metadata before the new on-disk metadata
              areas were designed and  no  longer  gets  tested.   It  is  not
              supported under low-memory conditions, and it is important never
              to edit these metadata files unless  you  fully  understand  how
              things  work: to make changes you should always use the tools as
              normal, or else vgcfgbackup, edit backup, vgcfgrestore.


       /etc/lvm/lvm.conf           /etc/lvm/archive            /etc/lvm/backup
       /etc/lvm/cache/.cache /var/lock/lvm


       lvm(8), umask(2), uname(2), dlopen(3), syslog(3), syslog.conf(5)