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More lvm.conf and tagging documentation.
This commit is contained in:
Alasdair Kergon
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166
man/lvm.conf.5
166
man/lvm.conf.5
@ -112,7 +112,8 @@ 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.
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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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@ -210,10 +211,167 @@ Defaults to /proc.
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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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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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\fBlocking_dir\fP \(em The directory LVM2 places its file locks
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if \fBlocking_type\fP is set to 1. The default is \fB/var/lock/lvm\fP.
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.IP
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\fBlocking_library\fP \(em The name of the external locking
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library to load if \fBlocking_type\fP is set to 2.
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The default is \fBlvm2_locking.so\fP. If you need to write
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such a library, look at the lib/locking source code directory.
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.TP
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\fBtags\fP \(em Host tag settings
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.IP
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\fBhosttags\fP \(em If set to 1, create a host tag with the machine name.
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Setting this to 0 does nothing, neither creating nor destroying any tag.
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The machine name used is the nodename as returned by \fBuname\fP (2).
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.IP
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Additional host tags to be set can be listed here as subsections.
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The @ prefix for tags is optional.
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Each of these host tag subsections can contain a \fBhost_list\fP
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array of host names. If any one of these entries matches the machine
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name exactly then the host tag gets defined on this particular host,
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otherwise it doesn't.
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.IP
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After lvm.conf has been processed, LVM2 works through each host
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tag that has been defined in turn, and if there is a configuration
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file called lvm_\fB<host_tag>\fP.conf it attempts to load it.
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Any settings read in override settings found in earlier files.
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Any additional host tags defined get appended to the search list,
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so in turn they can lead to further configuration files being processed.
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Use \fBlvm dumpconfig\fP to check the result of config
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file processing.
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.IP
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The following example always sets host tags \fBtag1\fP and
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sets \fBtag2\fP on machines fs1 and fs2:
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.IP
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tags { tag1 { } tag2 { host_list = [ "fs1", "fs2" ] } }
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.IP
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These options are useful if you are replicating configuration files
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around a cluster. Use of \fBhosttags = 1\fP means every machine
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can have static and identical local configuration files yet use
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different settings and activate different logical volumes by
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default. See also \fBvolume_list\fP below and \fB--addtag\fP
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in \fBlvm\fP (8).
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.TP
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\fBactivation\fP \(em Settings affecting device-mapper activation
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.IP
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\fBmissing_stripe_filler\fP \(em When activating an incomplete
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logical volume in partial mode, this missing data is replaced
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with this device. It could perhaps be a block device that always
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returns an error when it is accessed, or one that always
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returns zeros. See \fBlvcreate\fP (8) for how to create
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such devices.
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.IP
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\fBmirror_region_size\fP \(em Unit size in KB for copy operations
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when mirroring.
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.IP
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\fBreserved_memory\fP, \fBreserved_stack\fP \(em How many KB to reserve
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for LVM2 to use while logical volumes are suspended. If insufficient
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memory is reserved before suspension, there is a risk of machine deadlock.
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.IP
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\fBprocess_priority\fP \(em The nice value to use while devices are
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suspended. This is set to a high priority so that logical volumes
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are suspended (with I/O generated by other processes to those
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logical volumes getting queued) for the shortest possible time.
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.IP
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\fBvolume_list\fP \(em This acts as a filter through which
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all requests to activate a logical volume on this machine
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are passed. A logical volume is only activated if it matches
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an item in the list. Tags must be preceded by @ and are checked
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against all tags defined in the logical volume and volume group
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metadata for a match.
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@* is short-hand to check every tag set on the host machine (see
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\fBtags\fP above).
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Logical volume and volume groups can also be included in the list
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by name e.g. vg00, vg00/lvol1.
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.TP
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\fBmetadata\fP \(em Advanced metadata settings
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.IP
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\fBpvmetadatacopies\fP \(em When creating a physical volume using the
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LVM2 metadata format, this is the default number of copies of metadata
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to store on each physical volume.
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Currently it can be set to 0, 1 or 2. The default is 1.
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If set to 2, one copy is placed at the beginning of the disk
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and the other is placed at the end.
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It can be overridden on the command line with \fB--metadatacopies\fP.
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If creating a volume group with just one physical volume, it's a
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good idea to have 2 copies. If creating a large volume group with
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many physical volumes, you may decide that 3 copies of the metadata
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is sufficient, i.e. setting it to 1 on three of the physical volumes,
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and 0 on the rest. Every volume group must contain at least one
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physical volume with at least 1 copy of the metadata (unless using
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the text files described below). The disadvantage of having lots
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of copies is that every time the tools access the volume group, every
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copy of the metadata has to be accessed, and this slows down the
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tools.
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.IP
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\fBpvmetadatasize\fP \(em Approximate number of sectors to set aside
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for each copy of the metadata. Volume groups with large numbers of
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physical or logical volumes, or volumes groups containing complex
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logical volume structures will need additional space for their metadata.
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The metadata areas are treated as circular buffers, so
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unused space becomes filled with an archive of the most recent
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previous versions of the metadata.
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.IP
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\fBdirs\fP \(em List of directories holding live copies of LVM2
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metadata as text files. These directories must not be on logical
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volumes. It is possible to use LVM2 with a couple of directories
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here, preferably on different (non-logical-volume) filesystems
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and with no other on-disk metadata, \fBpvmetadatacopies = 0\fP.
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Alternatively these directories can be in addition to the
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on-disk metadata areas. This feature was created during the
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development of the LVM2 metadata before the new on-disk metadata
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areas were designed and no longer gets tested.
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It is not supported under low-memory conditions, and it is
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important never to edit these metadata files unless you fully
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understand how things work: to make changes you should always use
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the tools as normal, or else vgcfgbackup, edit backup, vgcfgrestore.
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.SH FILES
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.I /etc/lvm/lvm.conf
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.I /etc/lvm/.cache
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.I /etc/lvm/archive
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.I /etc/lvm/backup
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.I /var/lock/lvm
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.SH SEE ALSO
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.BR lvm (8)
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.BR umask (2)
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.BR syslog (3)
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.BR lvm (8),
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.BR umask (2),
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.BR uname (2),
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.BR dlopen (3),
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.BR syslog (3),
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.BR syslog.conf (5)
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