1LVM(8) System Manager's Manual LVM(8)
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6 lvm — LVM2 tools
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9 lvm [command|file]
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12 The Logical Volume Manager (LVM) provides tools to create virtual block
13 devices from physical devices. Virtual devices may be easier to manage
14 than physical devices, and can have capabilities beyond what the physi‐
15 cal devices provide themselves. A Volume Group (VG) is a collection of
16 one or more physical devices, each called a Physical Volume (PV). A
17 Logical Volume (LV) is a virtual block device that can be used by the
18 system or applications. Each block of data in an LV is stored on one
19 or more PV in the VG, according to algorithms implemented by Device
20 Mapper (DM) in the kernel.
21 The lvm command, and other commands listed below, are the command-line
23 tools for LVM. A separate manual page describes each command in de‐
24 tail.
25 If lvm is invoked with no arguments it presents a readline prompt (as‐
27 suming it was compiled with readline support). LVM commands may be en‐
28 tered interactively at this prompt with readline facilities including
29 history and command name and option completion. Refer to readline(3)
30 for details.
31 If lvm is invoked with argv[0] set to the name of a specific LVM com‐
33 mand (for example by using a hard or soft link) it acts as that com‐
34 mand.
35 On invocation, lvm requires that only the standard file descriptors
37 stdin, stdout and stderr are available. If others are found, they get
38 closed and messages are issued warning about the leak. This warning
39 can be suppressed by setting the environment variable LVM_SUP‐
40 PRESS_FD_WARNINGS.
41 Where commands take VG or LV names as arguments, the full path name is
43 optional. An LV called "lvol0" in a VG called "vg0" can be specified
44 as "vg0/lvol0". Where a list of VGs is required but is left empty, a
45 list of all VGs will be substituted. Where a list of LVs is required
46 but a VG is given, a list of all the LVs in that VG will be substi‐
47 tuted. So lvdisplay vg0 will display all the LVs in "vg0". Tags can
48 also be used - see --addtag below.
49 One advantage of using the built-in shell is that configuration infor‐
51 mation gets cached internally between commands.
52 A file containing a simple script with one command per line can also be
54 given on the command line. The script can also be executed directly if
55 the first line is #! followed by the absolute path of lvm.
56 Additional hyphens within option names are ignored. For example,
58 --readonly and --read-only are both accepted.
59
61 The following commands are built into lvm without links normally being
62 created in the filesystem for them.
63 config The same as lvmconfig(8) below.
65 devtypes Display the recognised built-in block device types.
66 dumpconfig The same as lvmconfig(8) below.
67 formats Display recognised metadata formats.
68 fullreport Report information about PVs, PV segments, VGs, LVs and
69 LV segments, all at once.
70 help Display the help text.
71 lastlog Display log report of last command run in LVM shell if
72 command log reporting is enabled.
73 lvpoll Complete lvmpolld operations (Internal command).
74 segtypes Display recognised Logical Volume segment types.
75 systemid Display any system ID currently set on this host.
76 tags Display any tags defined on this host.
77 version Display version information.
78
80 The following commands implement the core LVM functionality.
81 pvchange Change attributes of a Physical Volume.
83 pvck Check Physical Volume metadata.
84 pvcreate Initialize a disk or partition for use by LVM.
85 pvdisplay Display attributes of a Physical Volume.
86 pvmove Move Physical Extents.
87 pvremove Remove a Physical Volume.
88 pvresize Resize a disk or partition in use by LVM2.
89 pvs Report information about Physical Volumes.
90 pvscan Scan all disks for Physical Volumes.
91 vgcfgbackup Backup Volume Group descriptor area.
92 vgcfgrestore Restore Volume Group descriptor area.
93 vgchange Change attributes of a Volume Group.
94 vgck Check Volume Group metadata.
95 vgconvert Convert Volume Group metadata format.
96 vgcreate Create a Volume Group.
97 vgdisplay Display attributes of Volume Groups.
98 vgexport Make volume Groups unknown to the system.
99 vgextend Add Physical Volumes to a Volume Group.
100 vgimport Make exported Volume Groups known to the system.
101 vgimportclone Import and rename duplicated Volume Group (e.g. a hard‐
102 ware snapshot).
103 vgmerge Merge two Volume Groups.
104 vgmknodes Recreate Volume Group directory and Logical Volume spe‐
105 cial files
106 vgreduce Reduce a Volume Group by removing one or more Physical
107 Volumes.
108 vgremove Remove a Volume Group.
109 vgrename Rename a Volume Group.
110 vgs Report information about Volume Groups.
111 vgscan Scan all disks for Volume Groups.
112 vgsplit Split a Volume Group into two, moving any logical volumes
113 from one Volume Group to another by moving entire Physi‐
114 cal Volumes.
115 lvchange Change attributes of a Logical Volume.
116 lvconvert Convert a Logical Volume from linear to mirror or snap‐
117 shot.
118 lvcreate Create a Logical Volume in an existing Volume Group.
119 lvdisplay Display attributes of a Logical Volume.
120 lvextend Extend the size of a Logical Volume.
121 lvmconfig Display the configuration information after loading
122 lvm.conf(5) and any other configuration files.
123 lvmdiskscan Scan for all devices visible to LVM2.
124 lvmdump Create lvm2 information dumps for diagnostic purposes.
125 lvreduce Reduce the size of a Logical Volume.
126 lvremove Remove a Logical Volume.
127 lvrename Rename a Logical Volume.
128 lvresize Resize a Logical Volume.
129 lvs Report information about Logical Volumes.
130 lvscan Scan (all disks) for Logical Volumes.
131 The following LVM1 commands are not implemented in LVM2: lvmchange,
133 lvmsadc, lvmsar, pvdata. For performance metrics, use dmstats(8) or to
134 manipulate the kernel device-mapper driver used by LVM2 directly, use
135 dmsetup(8).
136
138 The valid characters for VG and LV names are: a-z A-Z 0-9 + _ . -
139 VG names cannot begin with a hyphen. The name of a new LV also cannot
141 begin with a hyphen. However, if the configuration setting meta‐
142 data/record_lvs_history is enabled then an LV name with a hyphen as a
143 prefix indicates that, although the LV was removed, it is still being
144 tracked because it forms part of the history of at least one LV that is
145 still present. This helps to record the ancestry of thin snapshots
146 even after some links in the chain have been removed. A reference to
147 the historical LV 'lvol1' in VG 'vg00' would be 'vg00/\-lvol1' or just
148 '-lvol1' if the VG is already set. (The latter form must be preceded
149 by '--' to terminate command line option processing before reaching
150 this argument.)
151 There are also various reserved names that are used internally by lvm
153 that can not be used as LV or VG names. A VG cannot be called anything
154 that exists in /dev/ at the time of creation, nor can it be called '.'
155 or '..'. An LV cannot be called '.', '..', 'snapshot' or 'pvmove'.
156 The LV name may also not contain any of the following strings:
157 '_cdata', '_cmeta', '_corig', '_mlog', '_mimage', '_pmspare', '_rim‐
158 age', '_rmeta', '_tdata', '_tmeta', '_vorigin' or '_vdata'. A direc‐
159 tory bearing the name of each Volume Group is created under /dev when
160 any of its Logical Volumes are activated. Each active Logical Volume
161 is accessible from this directory as a symbolic link leading to a de‐
162 vice node. Links or nodes in /dev/mapper are intended only for inter‐
163 nal use and the precise format and escaping might change between re‐
164 leases and distributions. Other software and scripts should use the
165 /dev/VolumeGroupName/LogicalVolumeName format to reduce the chance of
166 needing amendment when the software is updated. Should you need to
167 process the node names in /dev/mapper, you may use dmsetup splitname to
168 separate out the original VG, LV and internal layer names.
169
171 VG names should be unique. vgcreate will produce an error if the spec‐
172 ified VG name matches an existing VG name. However, there are cases
173 where different VGs with the same name can appear to LVM, e.g. after
174 moving disks or changing filters.
175 When VGs with the same name exist, commands operating on all VGs will
177 include all of the VGs with the same name. If the ambiguous VG name is
178 specified on the command line, the command will produce an error. The
179 error states that multiple VGs exist with the specified name. To
180 process one of the VGs specifically, the --select option should be used
181 with the UUID of the intended VG: '--select vg_uuid=<uuid>'.
182 An exception is if all but one of the VGs with the shared name is for‐
184 eign (see lvmsystemid(7).) In this case, the one VG that is not for‐
185 eign is assumed to be the intended VG and is processed.
186 LV names are unique within a VG. The name of an historical LV cannot
188 be reused until the historical LV has itself been removed or renamed.
189
192 When an operation needs to allocate Physical Extents for one or more
193 Logical Volumes, the tools proceed as follows:
194 First of all, they generate the complete set of unallocated Physical
196 Extents in the Volume Group. If any ranges of Physical Extents are
197 supplied at the end of the command line, only unallocated Physical Ex‐
198 tents within those ranges on the specified Physical Volumes are consid‐
199 ered.
200 Then they try each allocation policy in turn, starting with the
202 strictest policy (contiguous) and ending with the allocation policy
203 specified using --alloc or set as the default for the particular Logi‐
204 cal Volume or Volume Group concerned. For each policy, working from
205 the lowest-numbered Logical Extent of the empty Logical Volume space
206 that needs to be filled, they allocate as much space as possible ac‐
207 cording to the restrictions imposed by the policy. If more space is
208 needed, they move on to the next policy.
209 The restrictions are as follows:
211 Contiguous requires that the physical location of any Logical Extent
213 that is not the first Logical Extent of a Logical Volume is adjacent to
214 the physical location of the Logical Extent immediately preceding it.
215 Cling requires that the Physical Volume used for any Logical Extent to
217 be added to an existing Logical Volume is already in use by at least
218 one Logical Extent earlier in that Logical Volume. If the configura‐
219 tion parameter allocation/cling_tag_list is defined, then two Physical
220 Volumes are considered to match if any of the listed tags is present on
221 both Physical Volumes. This allows groups of Physical Volumes with
222 similar properties (such as their physical location) to be tagged and
223 treated as equivalent for allocation purposes.
224 When a Logical Volume is striped or mirrored, the above restrictions
226 are applied independently to each stripe or mirror image (leg) that
227 needs space.
228 Normal will not choose a Physical Extent that shares the same Physical
230 Volume as a Logical Extent already allocated to a parallel Logical Vol‐
231 ume (i.e. a different stripe or mirror image/leg) at the same offset
232 within that parallel Logical Volume.
233 When allocating a mirror log at the same time as Logical Volumes to
235 hold the mirror data, Normal will first try to select different Physi‐
236 cal Volumes for the log and the data. If that's not possible and the
237 allocation/mirror_logs_require_separate_pvs configuration parameter is
238 set to 0, it will then allow the log to share Physical Volume(s) with
239 part of the data.
240 When allocating thin pool metadata, similar considerations to those of
242 a mirror log in the last paragraph apply based on the value of the al‐
243 location/thin_pool_metadata_require_separate_pvs configuration parame‐
244 ter.
245 If you rely upon any layout behaviour beyond that documented here, be
247 aware that it might change in future versions of the code.
248 For example, if you supply on the command line two empty Physical Vol‐
250 umes that have an identical number of free Physical Extents available
251 for allocation, the current code considers using each of them in the
252 order they are listed, but there is no guarantee that future releases
253 will maintain that property. If it is important to obtain a specific
254 layout for a particular Logical Volume, then you should build it up
255 through a sequence of lvcreate(8) and lvconvert(8) steps such that the
256 restrictions described above applied to each step leave the tools no
257 discretion over the layout.
258 To view the way the allocation process currently works in any specific
260 case, read the debug logging output, for example by adding -vvvv to a
261 command.
262
264 Some logical volume types are simple to create and can be done with a
265 single lvcreate(8) command. The linear and striped logical volume
266 types are an example of this. Other logical volume types may require
267 more than one command to create. The cache (lvmcache(7)) and thin pro‐
268 visioning (lvmthin(7)) types are examples of this.
269
271 All tools return a status code of zero on success or non-zero on fail‐
272 ure. The non-zero codes distinguish only between the broad categories
273 of unrecognised commands, problems processing the command line argu‐
274 ments and any other failures. As LVM remains under active development,
275 the code used in a specific case occasionally changes between releases.
276 Message text may also change.
277
279 HOME Directory containing .lvm_history if the internal readline shell
280 is invoked.
281 LVM_OUT_FD
283 File descriptor to use for common output from LVM commands.
284 LVM_ERR_FD
286 File descriptor to use for error output from LVM commands.
287 LVM_REPORT_FD
289 File descriptor to use for report output from LVM commands.
290 LVM_COMMAND_PROFILE
292 Name of default command profile to use for LVM commands. This
293 profile is overriden by direct use of --commandprofile command
294 line option.
295 LVM_RUN_BY_DMEVENTD
297 This variable is normally set by dmeventd plugin to inform lvm2
298 command it is running from dmeventd plugin so lvm2 takes some
299 extra action to avoid comunication and deadlocks with dmeventd.
300 LVM_SYSTEM_DIR
302 Directory containing lvm.conf(5) and other LVM system files.
303 Defaults to "/etc/lvm".
304 LVM_SUPPRESS_FD_WARNINGS
306 Suppress warnings about unexpected file descriptors passed into
307 LVM.
308 LVM_SUPPRESS_SYSLOG
310 Suppress contacting syslog.
311 LVM_VG_NAME
313 The Volume Group name that is assumed for any reference to a
314 Logical Volume that doesn't specify a path. Not set by default.
315 LVM_LVMPOLLD_PIDFILE
317 Path to the file that stores the lvmpolld process ID.
318 LVM_LVMPOLLD_SOCKET
320 Path to the socket used to communicate with lvmpolld..
321 LVM_LOG_FILE_EPOCH
323 A string of up to 32 letters appended to the log filename and
324 followed by the process ID and a startup timestamp using this
325 format string "_%s_%d_%llu". When set, each process logs to a
326 separate file.
327 LVM_LOG_FILE_MAX_LINES
329 If more than this number of lines are sent to the log file, the
330 command gets aborted. Automated tests use this to terminate
331 looping commands.
332 LVM_EXPECTED_EXIT_STATUS
334 The status anticipated when the process exits. Use ">N" to
335 match any status greater than N. If the actual exit status
336 matches and a log file got produced, it is deleted.
337 LVM_LOG_FILE_EPOCH and LVM_EXPECTED_EXIT_STATUS together allow
338 automated test scripts to discard uninteresting log data.
339 LVM_SUPPRESS_LOCKING_FAILURE_MESSAGES
341 Used to suppress warning messages when the configured locking is
342 known to be unavailable.
343 DM_ABORT_ON_INTERNAL_ERRORS
345 Abort processing if the code detects a non-fatal internal error.
346 DM_DISABLE_UDEV
348 Avoid interaction with udev. LVM will manage the relevant nodes
349 in /dev directly.
350 DM_DEBUG_WITH_LINE_NUMBERS
352 Prepends source file name and code line number with libdm debug‐
353 ging.
354
356 /etc/lvm/lvm.conf
357 $HOME/.lvm_history
358
360 lvm(8) lvm.conf(5) lvmconfig(8)
361 pvchange(8) pvck(8) pvcreate(8) pvdisplay(8) pvmove(8) pvremove(8)
363 pvresize(8) pvs(8) pvscan(8)
364 vgcfgbackup(8) vgcfgrestore(8) vgchange(8) vgck(8) vgcreate(8)
366 vgconvert(8) vgdisplay(8) vgexport(8) vgextend(8) vgimport(8)
367 vgimportclone(8) vgmerge(8) vgmknodes(8) vgreduce(8) vgremove(8)
368 vgrename(8) vgs(8) vgscan(8) vgsplit(8)
369 lvcreate(8) lvchange(8) lvconvert(8) lvdisplay(8) lvextend(8)
371 lvreduce(8) lvremove(8) lvrename(8) lvresize(8) lvs(8) lvscan(8)
372 lvm-fullreport(8) lvm-lvpoll(8) lvm2-activation-generator(8)
374 blkdeactivate(8) lvmdump(8)
375 dmeventd(8) lvmpolld(8) lvmlockd(8) lvmlockctl(8) cmirrord(8)
377 lvmdbusd(8)
378 lvmsystemid(7) lvmreport(7) lvmraid(7) lvmthin(7) lvmcache(7)
380 dmsetup(8), dmstats(8), readline(3)
382Red Hat, Inc. LVM TOOLS 2.03.11(2) (2021-01-08) LVM(8)