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 provides a wide
choice of acceptable indentation styles. Comments begin with # and continue to
the end of the line. They are treated as whitespace.
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 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 "/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 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 (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
output.
- 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
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 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, 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=internal (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 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
liblvm2clusterlock.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
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 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
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 time.
- 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.
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)