lvm.conf
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
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 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-map-
per 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 satisfac-
torily 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 impossi-
ble 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 commu-
nicate 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 con-
tain code to process different formats of metadata. For exam-
ple, 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-clus-
ter=internal (the default) then 3 means to use built-in clus-
ter-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
configuration file called lvm_<host_tag>.conf it attempts to
load it. Any settings read in override settings found in ear-
lier files. Any additional host tags defined get appended to
the search list, so in turn they can lead to further configura-
tion 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 vol-
umes 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 missing data is replaced with this
device. It could perhaps be a block device that always returns
an error when it is accessed, or one that always returns zeros.
See lvcreate (8) for how to create such devices.
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
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 --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
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 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
development of the LVM2 metadata before the new on-disk meta-
data 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, vgcfgre-
store.
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 LVM.CONF(5)
