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632 lines
29 KiB
Groff
632 lines
29 KiB
Groff
.TH LVM.CONF 5 "LVM TOOLS #VERSION#" "Sistina Software UK" \" -*- nroff -*-
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.SH NAME
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lvm.conf \- Configuration file for LVM2
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.SH SYNOPSIS
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.B #DEFAULT_SYS_DIR#/lvm.conf
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.SH DESCRIPTION
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\fBlvm.conf\fP is loaded during the initialisation phase of
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\fBlvm\fP(8). This file can in turn lead to other files
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being loaded - settings read in later override earlier
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settings. File timestamps are checked between commands and if
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any have changed, all the files are reloaded.
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The settings defined in lvm.conf can be overridden by any
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of these extended configuration methods:
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.TP
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.B tag config
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.br
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See \fBtags\fP configuration setting description below.
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.TP
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.B profile config
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.br
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A profile is a set of selected customizable configuration settings
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that are aimed to achieve a certain characteristics in various
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environments or uses. Normally, the name of the profile should
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reflect that environment or use.
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LVM itself provides a few predefined configuration profiles.
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Users are allowed to add more profiles with different values if needed.
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For this purpose, there's the \fBdefault.profile\fP which contains all
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settings that are customizable by profiles. Users are encouraged
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to copy this default profile and edit it as needed. Alternatively,
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the \fBlvm dumpconfig --file <ProfileName.profile> --type profilable <section>\fP
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can be used to generate a configuration with profilable settings for
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given section and save it to new ProfileName.profile (if the section
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is not specified, all profilable settings are reported).
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The profiles are stored in #DEFAULT_PROFILE_DIR# directory by default.
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This location can be changed using the \fBconfig/profile_dir\fP setting.
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Each profile configuration is stored in \fBProfileName.profile\fP file
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in the profile directory. When referencing the profile, the \fB.profile\fP
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suffix is left out.
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The profile to use can be defined for each LVM command using the \fB\-\-profile ProfileName\fP
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command line option. When using a profile while creating Volume
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Groups or Logical Volumes, the ProfileName is stored in Volume Group
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metadata. When using such volumes later on, the profile is automatically
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loaded and applied. If Volume Group and any of its Logical Volumes have different
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profiles defined, the profile defined for the Logical Volume is used. Profiles
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attached to Volume Groups or Logical Volumes can be changed or detached
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using the \fBvgchange\fP(8) and \fBlvchange\fP(8) commands with \fB\-\-profile ProfileName\fP
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or \fB\-\-detachprofile\fP options. For any other LVM command, the \fB\-\-profile ProfileName\fP
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option causes the profile to be applied only temporarily during the command
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execution for any existing Volume Group or Logical Volume.
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The \fBvgs\fP and \fBlvs\fP reporting commands provide \fB-o vg_profile\fP and
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\fB-o lv_profile\fP output options to show the profile currently attached to a
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Volume Group or a Logical Volume.
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.TP
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.B direct config override on command line
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The \fB\-\-config ConfigurationString\fP command line option takes the
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ConfigurationString as direct string representation of the configuration
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to override the existing configuration. The ConfigurationString is of
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exactly the same format as used in any LVM configuration file.
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.LP
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When several configuration methods are used at the same time
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and when LVM looks for the value of a particular setting, it traverses
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this \fBconfig cascade\fP from left to right:
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\fBdirect config override on command line\fP -> \fBprofile config\fP -> \fBtag config\fP -> \fBlvm.conf\fP.
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No part of this cascade is compulsory. If there's no setting value found at
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the end of the cascade, a default value is used for that setting.
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Use \fBlvm dumpconfig\fP to check what settings are in use and what
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the default values are.
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.SH SYNTAX
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.LP
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This section describes the configuration file syntax.
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.LP
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Whitespace is not significant unless it is within quotes.
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This provides a wide choice of acceptable indentation styles.
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Comments begin with # and continue to the end of the line.
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They are treated as whitespace.
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.LP
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Here is an informal grammar:
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.TP
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.BR file " = " value *
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.br
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A configuration file consists of a set of values.
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.TP
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.BR value " = " section " | " assignment
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.br
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A value can either be a new section, or an assignment.
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.TP
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.BR section " = " identifier " '" { "' " value "* '" } '
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.br
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A section is groups associated values together.
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.br
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It is denoted by a name and delimited by curly brackets.
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.br
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e.g. backup {
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.br
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...
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.br
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}
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.TP
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.BR assignment " = " identifier " '" = "' ( " array " | " type " )"
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.br
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An assignment associates a type with an identifier.
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.br
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e.g. level = 7
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.br
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.TP
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.BR array " = '" [ "' ( " type " '" , "')* " type " '" ] "' | '" [ "' '" ] '
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.br
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Inhomogeneous arrays are supported.
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.br
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Elements must be separated by commas.
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.br
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An empty array is acceptable.
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.TP
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.BR type " = " integer " | " float " | " string
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.BR integer " = [0-9]*"
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.br
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.BR float " = [0-9]*'" . '[0-9]*
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.br
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.B string \fR= '\fB"\fR'.*'\fB"\fR'
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.IP
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Strings must be enclosed in double quotes.
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.SH SECTIONS
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.LP
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The sections that may be present in the file are:
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.TP
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\fBdevices\fP \(em Device settings
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.IP
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\fBdir\fP \(em Directory in which to create volume group device nodes.
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Defaults to "/dev". Commands also accept this as a prefix on volume
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group names.
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.IP
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\fBscan\fP \(em List of directories to scan recursively for
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LVM physical volumes.
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Devices in directories outside this hierarchy will be ignored.
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Defaults to "/dev".
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.IP
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\fBpreferred_names\fP \(em List of patterns compared in turn against
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all the pathnames referencing the same device in in the scanned directories.
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The pathname that matches the earliest pattern in the list is the
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one used in any output. As an example, if device-mapper multipathing
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is used, the following will select multipath device names:
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.br
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\fBdevices { preferred_names = [ "^/dev/mapper/mpath" ] }\fP
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.IP
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\fBfilter\fP \(em List of patterns to apply to devices found by a scan.
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Patterns are regular expressions delimited by any character and preceded
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by \fBa\fP (for accept) or \fBr\fP (for reject). The list is traversed
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in order, and the first regex that matches determines if the device
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will be accepted or rejected (ignored). Devices that don't match
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any patterns are accepted. If you want to reject patterns that
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don't match, end the list with "r/.*/".
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If there are several names for the same device (e.g. symbolic links
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in /dev), if the first matching pattern in the list for any of the names is an
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\fBa\fP pattern, the device is accepted; otherwise if the first matching
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pattern in the list for any of the names is an \fBr\fP pattern it is rejected;
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otherwise it is accepted. As an example, to ignore /dev/cdrom you could use:
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.br
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\fBdevices { filter=["r|cdrom|"] }\fP
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.IP
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\fBglobal_filter\fP \(em Since "filter" might get overridden from the command line, it
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is not suitable for system-wide device filtering (udev rules, lvmetad). To hide
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devices from LVM-specific udev processing and/or from lvmetad, you need to set
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global_filter. The syntax is the same as for normal "filter" above. Devices that
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fail the global_filter are not even opened by LVM.
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.IP
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\fBcache_dir\fP \(em Persistent filter cache file directory.
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Defaults to "#DEFAULT_CACHE_DIR#".
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.IP
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\fBwrite_cache_state\fP \(em Set to 0 to disable the writing out of the
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persistent filter cache file when \fBlvm\fP exits.
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Defaults to 1.
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.IP
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\fBtypes\fP \(em List of pairs of additional acceptable block device types
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found in /proc/devices together with maximum (non-zero) number of
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partitions (normally 16). By default, LVM2 supports ide, sd, md, loop,
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dasd, dac960, nbd, ida, cciss, ubd, ataraid, drbd, power2, i2o_block
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and iseries/vd. Block devices with major
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numbers of different types are ignored by LVM2.
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Example: \fBtypes = ["fd", 16]\fP.
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To create physical volumes on device-mapper volumes
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created outside LVM2, perhaps encrypted ones from \fBcryptsetup\fP,
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you'll need \fBtypes = ["device-mapper", 16]\fP. But if you do this,
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be careful to avoid recursion within LVM2. The figure for number
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of partitions is not currently used in LVM2 - and might never be.
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.IP
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\fBsysfs_scan\fP \(em If set to 1 and your kernel supports sysfs and
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it is mounted, sysfs will be used as a quick way of filtering out
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block devices that are not present.
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.IP
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\fBmd_component_detection\fP \(em If set to 1, LVM2 will ignore devices
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used as components of software RAID (md) devices by looking for md
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superblocks. This doesn't always work satisfactorily e.g. if a device
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has been reused without wiping the md superblocks first.
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.IP
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\fBmd_chunk_alignment\fP \(em If set to 1, and a Physical Volume is placed
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directly upon an md device, LVM2 will align its data blocks with the
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md device's stripe-width.
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.IP
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\fBdata_alignment_detection\fP \(em If set to 1, and your kernel provides
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topology information in sysfs for the Physical Volume, the start of data
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area will be aligned on a multiple of the ’minimum_io_size’ or
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’optimal_io_size’ exposed in sysfs. minimum_io_size is the smallest
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request the device can perform without incurring a read-modify-write
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penalty (e.g. MD's chunk size). optimal_io_size is the device's
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preferred unit of receiving I/O (e.g. MD's stripe width). minimum_io_size
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is used if optimal_io_size is undefined (0). If both \fBmd_chunk_alignment\fP
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and \fBdata_alignment_detection\fP are enabled the result of
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\fBdata_alignment_detection\fP is used.
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.IP
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\fBdata_alignment\fP \(em Default alignment (in KB) of start of data area
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when creating a new Physical Volume using the \fBlvm2\fP format.
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If a Physical Volume is placed directly upon an md device and
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\fBmd_chunk_alignment\fP or \fBdata_alignment_detection\fP is enabled
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this parameter is ignored. Set to 0 to use the default alignment of
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64KB or the page size, if larger.
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.IP
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\fBdata_alignment_offset_detection\fP \(em If set to 1, and your kernel
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provides topology information in sysfs for the Physical Volume, the
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start of the aligned data area of the Physical Volume will be shifted
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by the alignment_offset exposed in sysfs.
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.sp
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To see the location of the first Physical Extent of an existing Physical Volume
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use \fBpvs -o +pe_start\fP . It will be a multiple of the requested
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\fBdata_alignment\fP plus the alignment_offset from
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\fBdata_alignment_offset_detection\fP (if enabled) or the pvcreate
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commandline.
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.IP
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\fBdisable_after_error_count\fP \(em During each LVM operation errors received
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from each device are counted. If the counter of a particular device exceeds
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the limit set here, no further I/O is sent to that device for the remainder of
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the respective operation. Setting the parameter to 0 disables the counters
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altogether.
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.IP
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\fBpv_min_size\fP \(em
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Minimal size (in KB) of the block device which can be used as a PV.
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In clustered environment all nodes have to use the same value.
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Any value smaller than 512KB is ignored. Up to and include version 2.02.84
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the default was 512KB. From 2.02.85 onwards it was changed to 2MB to
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avoid floppy drives by default.
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.IP
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\fBissue_discards\fP \(em
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Issue discards to a logical volumes's underlying physical volume(s) when the
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logical volume is no longer using the physical volumes' space (e.g. lvremove,
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lvreduce, etc). Discards inform the storage that a region is no longer in use.
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Storage that supports discards advertise the protocol specific way discards
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should be issued by the kernel (TRIM, UNMAP, or WRITE SAME with UNMAP bit set).
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Not all storage will support or benefit from discards but SSDs and thinly
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provisioned LUNs generally do. If set to 1, discards will only be issued if
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both the storage and kernel provide support.
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.IP
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.TP
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\fBallocation\fP \(em Space allocation policies
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.IP
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\fBcling_tag_list\fP \(em List of PV tags matched by the \fBcling\fP allocation policy.
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.IP
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When searching for free space to extend an LV, the \fBcling\fP
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allocation policy will choose space on the same PVs as the last
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segment of the existing LV. If there is insufficient space and a
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list of tags is defined here, it will check whether any of them are
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attached to the PVs concerned and then seek to match those PV tags
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between existing extents and new extents.
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.IP
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The @ prefix for tags is required.
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Use the special tag "@*" as a wildcard to match any PV tag and so use
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all PV tags for this purpose.
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.IP
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For example, LVs are mirrored between two sites within a single VG.
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PVs are tagged with either @site1 or @site2 to indicate where
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they are situated and these two PV tags are selected for use with this
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allocation policy:
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.IP
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cling_tag_list = [ "@site1", "@site2" ]
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.TP
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\fBlog\fP \(em Default log settings
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.IP
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\fBfile\fP \(em Location of log file. If this entry is not present, no
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log file is written.
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.IP
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\fBoverwrite\fP \(em Set to 1 to overwrite the log file each time a tool
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is invoked. By default tools append messages to the log file.
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.IP
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\fBlevel\fP \(em Log level (0-9) of messages to write to the file.
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9 is the most verbose; 0 should produce no output.
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.IP
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\fBverbose\fP \(em Default level (0-3) of messages sent to stdout or stderr.
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3 is the most verbose; 0 should produce the least output.
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.IP
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\fBsilent\fP \(em Set to 1 to suppress all non-essential tool output.
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When set, display and reporting tools will still write the requested
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device properties to standard output, but messages confirming that
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something was or wasn't changed will be reduced to the 'verbose' level
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and not appear unless -v is supplied.
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.IP
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\fBsyslog\fP \(em Set to 1 (the default) to send log messages through syslog.
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Turn off by setting to 0. If you set to an integer greater than one,
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this is used - unvalidated - as the facility. The default is LOG_USER.
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See /usr/include/sys/syslog.h for safe facility values to use.
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For example, LOG_LOCAL0 might be 128.
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.IP
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\fBindent\fP \(em When set to 1 (the default) messages are indented
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according to their severity, two spaces per level.
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Set to 0 to turn off indentation.
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.IP
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\fBcommand_names\fP \(em When set to 1, the command name is used as a
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prefix for each message.
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Default is 0 (off).
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.IP
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\fBprefix\fP \(em Prefix used for all messages (after the command name).
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Default is two spaces.
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.IP
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\fBactivation\fP \(em Set to 1 to log messages while
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devices are suspended during activation.
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Only set this temporarily while debugging a problem because
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in low memory situations this setting can cause your machine to lock up.
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.TP
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\fBbackup\fP \(em Configuration for metadata backups.
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.IP
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\fBarchive_dir\fP \(em Directory used for automatic metadata archives.
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Backup copies of former metadata for each volume group are archived here.
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Defaults to "#DEFAULT_ARCHIVE_DIR#".
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.IP
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\fBbackup_dir\fP \(em Directory used for automatic metadata backups.
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A single backup copy of the current metadata for each volume group
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is stored here.
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Defaults to "#DEFAULT_BACKUP_DIR#".
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.IP
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\fBarchive\fP \(em Whether or not tools automatically archive existing
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metadata into \fBarchive_dir\fP before making changes to it.
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Default is 1 (automatic archives enabled).
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Set to 0 to disable.
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Disabling this might make metadata recovery difficult or impossible
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if something goes wrong.
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.IP
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\fBbackup\fP \(em Whether or not tools make an automatic backup
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into \fBbackup_dir\fP after changing metadata.
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Default is 1 (automatic backups enabled). Set to 0 to disable.
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Disabling this might make metadata recovery difficult or impossible
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if something goes wrong.
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.IP
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\fBretain_min\fP \(em Minimum number of archives to keep.
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Defaults to 10.
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.IP
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\fBretain_days\fP \(em Minimum number of days to keep archive files.
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Defaults to 30.
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.TP
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\fBshell\fP \(em LVM2 built-in readline shell settings
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.IP
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\fBhistory_size\fP \(em Maximum number of lines of shell history to retain (default 100) in $HOME/.lvm_history
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.TP
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\fBglobal\fP \(em Global settings
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.IP
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\fBtest\fP \(em If set to 1, run tools in test mode i.e. no changes to
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the on-disk metadata will get made. It's equivalent to having the
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-t option on every command.
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.IP
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\fBactivation\fP \(em Set to 0 to turn off all communication with
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the device-mapper driver. Useful if you want to manipulate logical
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volumes while device-mapper is not present in your kernel.
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.IP
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\fBproc\fP \(em Mount point of proc filesystem.
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Defaults to /proc.
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.IP
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\fBumask\fP \(em File creation mask for any files and directories created.
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Interpreted as octal if the first digit is zero.
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Defaults to 077.
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Use 022 to allow other users to read the files by default.
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.IP
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\fBformat\fP \(em The default value of \fB--metadatatype\fP used
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to determine which format of metadata to use when creating new
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physical volumes and volume groups. \fBlvm1\fP or \fBlvm2\fP.
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.IP
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\fBfallback_to_lvm1\fP \(em Set this to 1 if you need to
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be able to switch between 2.4 kernels using LVM1 and kernels
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including device-mapper.
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The LVM2 tools should be installed as normal and
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the LVM1 tools should be installed with a .lvm1 suffix e.g.
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vgscan.lvm1.
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If an LVM2 tool is then run but unable to communicate
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with device-mapper, it will automatically invoke the equivalent LVM1
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version of the tool. Note that for LVM1 tools to
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manipulate physical volumes and volume groups created by LVM2 you
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must use \fB--metadataformat lvm1\fP when creating them.
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.IP
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\fBlibrary_dir\fP \(em A directory searched for LVM2's shared libraries
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ahead of the places \fBdlopen\fP (3) searches.
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.IP
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\fBformat_libraries\fP \(em A list of shared libraries to load that contain
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code to process different formats of metadata. For example, liblvm2formatpool.so
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is needed to read GFS pool metadata if LVM2 was configured \fB--with-pool=shared\fP.
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.IP
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\fBlocking_type\fP \(em What type of locking to use.
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1 is the default, which use flocks on files in \fBlocking_dir\fP
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(see below) to
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avoid conflicting LVM2 commands running concurrently on a single
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machine. 0 disables locking and risks corrupting your metadata.
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If set to 2, the tools will load the external \fBlocking_library\fP
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(see below).
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If the tools were configured \fB--with-cluster=internal\fP
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(the default) then 3 means to use built-in cluster-wide locking.
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Type 4 enforces read-only metadata and forbids any operations that
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might want to modify Volume Group metadata.
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All changes to logical volumes and their states are communicated
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using locks.
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.IP
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\fBwait_for_locks\fP \(em When set to 1, the default, the tools
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wait if a lock request cannot be satisfied immediately.
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When set to 0, the operation is aborted instead.
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.IP
|
||
\fBlocking_dir\fP \(em The directory LVM2 places its file locks
|
||
if \fBlocking_type\fP is set to 1. The default is \fB/var/lock/lvm\fP.
|
||
.IP
|
||
\fBlocking_library\fP \(em The name of the external locking
|
||
library to load if \fBlocking_type\fP is set to 2.
|
||
The default is \fBliblvm2clusterlock.so\fP. If you need to write
|
||
such a library, look at the lib/locking source code directory.
|
||
.IP
|
||
\fBuse_lvmetad\fP \(em Whether to use (trust) a running instance of lvmetad. If
|
||
this is set to 0, all commands fall back to the usual scanning mechanisms. When
|
||
set to 1 \fBand\fP when lvmetad is running (it is not auto-started), the volume
|
||
group metadata and PV state flags are obtained from the lvmetad instance and no
|
||
scanning is done by the individual commands. In a setup with lvmetad, lvmetad
|
||
udev rules \fBmust\fP be set up for LVM to work correctly. Without proper udev
|
||
rules, all changes in block device configuration will be \fBignored\fP until a
|
||
manual 'pvscan --cache' is performed.
|
||
.br
|
||
If lvmetad has been running while use_lvmetad was 0, it \fBMUST\fP be stopped before
|
||
changing use_lvmetad to 1 and started again afterwards.
|
||
.TP
|
||
\fBtags\fP \(em Host tag settings
|
||
.IP
|
||
\fBhosttags\fP \(em 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 \fBuname\fP (2).
|
||
.IP
|
||
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 \fBhost_list\fP
|
||
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.
|
||
.IP
|
||
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_\fB<host_tag>\fP.conf it attempts to load it.
|
||
The activation/volume_list, devices/filter and devices/types settings are merged
|
||
(these all are lists), otherwise 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 \fBlvm dumpconfig\fP to check the result of config
|
||
file processing.
|
||
.IP
|
||
The following example always sets host tags \fBtag1\fP and
|
||
sets \fBtag2\fP on machines fs1 and fs2:
|
||
.IP
|
||
tags { tag1 { } tag2 { host_list = [ "fs1", "fs2" ] } }
|
||
.IP
|
||
These options are useful if you are replicating configuration files
|
||
around a cluster. Use of \fBhosttags = 1\fP means every machine
|
||
can have static and identical local configuration files yet use
|
||
different settings and activate different logical volumes by
|
||
default. See also \fBvolume_list\fP below and \fB--addtag\fP
|
||
in \fBlvm\fP (8).
|
||
.TP
|
||
\fBactivation\fP \(em Settings affecting device-mapper activation
|
||
.IP
|
||
\fBmissing_stripe_filler\fP \(em 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 \fBlvcreate\fP (8).
|
||
.IP
|
||
\fBmirror_region_size\fP \(em Unit size in KB for copy operations
|
||
when mirroring.
|
||
.IP
|
||
\fBreadahead\fP \(em Used when there is no readahead value stored
|
||
in the volume group metadata. Set to \fBnone\fP to disable
|
||
readahead in these circumstances or \fBauto\fP to use the default
|
||
value chosen by the kernel.
|
||
.IP
|
||
\fBreserved_memory\fP, \fBreserved_stack\fP \(em 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.
|
||
.IP
|
||
\fBprocess_priority\fP \(em 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.
|
||
.IP
|
||
\fBvolume_list\fP \(em 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
|
||
\fBtags\fP above).
|
||
Logical volume and volume groups can also be included in the list
|
||
by name e.g. vg00, vg00/lvol1.
|
||
If this setting is not present but at least one host tag is defined
|
||
then a default single-entry list containing @* is assumed.
|
||
.IP
|
||
\fBauto_activation_volume_list\fP \(em This acts as a filter through
|
||
which all requests to autoactivate a logical volume on this machine
|
||
are passed. A logical volume is autoactivated if it matches
|
||
an item in the list. Volumes must also pass the \fBvolume_list\fP
|
||
filter, if present. 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 \fBtags\fP above).
|
||
Logical volume and volume groups can also be included in the list
|
||
by name e.g. vg00, vg00/lvol1.
|
||
.IP
|
||
\fBread_only_volume_list\fP \(em This acts as a filter through
|
||
which all requests to activate a logical volume on this machine
|
||
are passed. A logical volume is activated in read-only mode (instead
|
||
of read-write) if it matches an item in the list. Volumes must first
|
||
pass the \fBvolume_list\fP filter, if present. 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
|
||
\fBtags\fP above).
|
||
Logical volume and volume groups can also be included in the list
|
||
by name e.g. vg00, vg00/lvol1.
|
||
.TP
|
||
\fBmetadata\fP \(em Advanced metadata settings
|
||
.IP
|
||
\fBpvmetadatacopies\fP \(em 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 \fB--pvmetadatacopies\fP
|
||
(see \fBpvcreate\fP).
|
||
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.
|
||
.IP
|
||
\fBpvmetadatasize\fP \(em 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.
|
||
.IP
|
||
\fBpvmetadataignore\fP When creating a physical volume using the LVM2
|
||
metadata format, this states whether metadata areas should be ignored.
|
||
The default is "n". If metadata areas on a physical volume are ignored,
|
||
LVM will not not store metadata in the metadata areas present on newly
|
||
created Physical Volumes. The option can be overridden on the command
|
||
line with \fB--metadataignore\fP (See \fBpvcreate\fP and \fBpvchange\fP).
|
||
Metadata areas cannot be created or extended after Logical Volumes have
|
||
been allocated on the device.
|
||
If you do not want to store metadata on this device, it is still wise
|
||
always to allocate a metadata area (use a non-zero value for
|
||
\fB--pvmetadatacopies\fP) in case you need it in the future and to use
|
||
this option to instruct LVM2 to ignore it.
|
||
.IP
|
||
\fBvgmetadatacopies\fP \(em When creating a volume group using the
|
||
LVM2 metadata format, this is the default number of copies of metadata
|
||
desired across all the physical volumes in the volume group. If set to
|
||
a non-zero value, LVM will automatically set or clear the metadataignore
|
||
flag on the physical volumes (see \fBpvcreate\fP and \fBpvchange\fP
|
||
\fB--metadataignore\fP) in order to achieve the desired number of metadata
|
||
copies. An LVM command that adds or removes physical volumes (for example,
|
||
\fBvgextend\fP, \fBvgreduce\fP, \fBvgsplit\fP, or \fBvgmerge\fP), may cause
|
||
LVM to automatically set or clear the metadataignore flags. Also, if
|
||
physical volumes go missing or reappear, or a new number of copies is
|
||
explicitly set (see \fBvgchange --vgmetadatacopies\fP), LVM may adjust
|
||
the metadataignore flags.
|
||
Set \fBvgmetadatacopies\fP to 0 instructs LVM not to set or clear the
|
||
metadataignore flags automatically. You may set a value larger than the
|
||
sum of all metadata areas on all physical volumes. The value can
|
||
be overridden on the command line with \fB--vgmetadatacopies\fP for various
|
||
commands (for example, \fBvgcreate\fP and \fBvgchange\fP), and can be
|
||
queryied with the \fBvg_mda_copies\fP field of \fBvgs\fP. This option
|
||
is useful for volume groups containing large numbers of physical volumes
|
||
with metadata as it may be used to minimize metadata read and write overhead.
|
||
.IP
|
||
\fBdirs\fP \(em 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, \fBpvmetadatacopies = 0\fP.
|
||
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.
|
||
.SH FILES
|
||
.I #DEFAULT_SYS_DIR#/lvm.conf
|
||
.br
|
||
.I #DEFAULT_ARCHIVE_DIR#
|
||
.br
|
||
.I #DEFAULT_BACKUP_DIR#
|
||
.br
|
||
.I #DEFAULT_CACHE_DIR#/.cache
|
||
.br
|
||
.I #DEFAULT_LOCK_DIR#
|
||
.SH SEE ALSO
|
||
.BR lvm (8),
|
||
.BR umask (2),
|
||
.BR uname (2),
|
||
.BR dlopen (3),
|
||
.BR syslog (3),
|
||
.BR syslog.conf (5)
|