LVM.CONF(5)                                                        LVM.CONF(5)



NAME
       lvm.conf - Configuration file for LVM2

SYNOPSIS
       /etc/lvm/lvm.conf

DESCRIPTION
       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.

SYNTAX
       This section describes the configuration file syntax.

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

       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.


SECTIONS
       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  tra-
              versed  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 "/etc/lvm/cache".

              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 crypt-
              setup, 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 (em 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 (em 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
              first.

       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  out-
              put.

              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 sus-
              pended during  activation.   Only  set  this  temporarily  while
              debugging  a  problem because in low memory situations this set-
              ting 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.   Dis-
              abling 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
              wrong.

              retain_min -- Minimum number of archives to keep.   Defaults  to
              10.

              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 cre-
              ated.   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 vol-
              umes 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 communi-
              cate with device-mapper, it will automatically invoke the equiv-
              alent 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 con-
              tain code to process different formats of metadata. For example,
              liblvm2formatpool.so 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=inter-
              nal (the default) then 3  means  to  use  built-in  cluster-wide
              locking.   All  changes  to logical volumes and their states are
              communicated using locks.

              locking_dir -- The directory LVM2 places its file locks if lock-
              ing_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  liblvm2clus-
              terlock.so.   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 subsec-
              tions.  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 configura-
              tion 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 con-
              fig 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
              mirroring.

              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 insuffi-
              cient memory is reserved before suspension, there is a  risk  of
              machine deadlock.

              process_priority -- The nice value to use while devices are sus-
              pended.  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  time.

              volume_list  -- This acts as a filter through which all requests
              to activate a logical volume on this machine are passed.  A log-
              ical 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 --meta-
              datacopies.  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  meta-
              data 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 com-
              plex 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  vol-
              umes.   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 devel-
              opment of the LVM2 metadata  before  the  new  on-disk  metadata
              areas  were  designed and no longer gets tested.  It is not sup-
              ported 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.

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

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



Sistina Software UK    LVM TOOLS 2.02.44-cvs (02-17-09)            LVM.CONF(5)

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