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 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.
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.
/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)