1LVMLOCKD(8) LVMLOCKD(8)
2
6 lvmlockd — LVM locking daemon
7
10 LVM commands use lvmlockd to coordinate access to shared storage.
11 When LVM is used on devices shared by multiple hosts, locks will:
12 · coordinate reading and writing of LVM metadata
14 · validate caching of LVM metadata
15 · prevent conflicting activation of logical volumes
16 lvmlockd uses an external lock manager to perform basic locking.
18 Lock manager (lock type) options are:
19 · sanlock: places locks on disk within LVM storage.
21 · dlm: uses network communication and a cluster manager.
22
25 lvmlockd [options]
26 For default settings, see lvmlockd -h.
28 --help | -h
30 Show this help information.
31 --version | -V
33 Show version of lvmlockd.
34 --test | -T
36 Test mode, do not call lock manager.
37 --foreground | -f
39 Don't fork.
40 --daemon-debug | -D
42 Don't fork and print debugging to stdout.
43 --pid-file | -p path
45 Set path to the pid file.
46 --socket-path | -s path
48 Set path to the socket to listen on.
49 --syslog-priority | -S err|warning|debug
51 Write log messages from this level up to syslog.
52 --gl-type | -g sanlock|dlm
54 Set global lock type to be sanlock or dlm.
55 --host-id | -i num
57 Set the local sanlock host id.
58 --host-id-file | -F path
60 A file containing the local sanlock host_id.
61 --sanlock-timeout | -o seconds
63 Override the default sanlock I/O timeout.
64 --adopt | -A 0|1
66 Adopt locks from a previous instance of lvmlockd.
67
71 Initial set up
72 Setting up LVM to use lvmlockd and a shared VG for the first time
73 includes some one time set up steps:
74 1. choose a lock manager
77 dlm
78 If dlm (or corosync) are already being used by other cluster software,
79 then select dlm. dlm uses corosync which requires additional configu‐
80 ration beyond the scope of this document. See corosync and dlm docu‐
81 mentation for instructions on configuration, set up and usage.
82 sanlock
84 Choose sanlock if dlm/corosync are not otherwise required. sanlock
85 does not depend on any clustering software or configuration.
86 2. configure hosts to use lvmlockd
89 On all hosts running lvmlockd, configure lvm.conf:
90 locking_type = 1
91 use_lvmlockd = 1
92 sanlock
94 Assign each host a unique host_id in the range 1-2000 by setting
95 /etc/lvm/lvmlocal.conf local/host_id
96 3. start lvmlockd
99 Start the lvmlockd daemon.
100 Use systemctl, a cluster resource agent, or run directly, e.g.
101 systemctl start lvm2-lvmlockd
102 4. start lock manager
105 sanlock
106 Start the sanlock and wdmd daemons.
107 Use systemctl or run directly, e.g.
108 systemctl start wdmd sanlock
109 dlm
111 Start the dlm and corosync daemons.
112 Use systemctl, a cluster resource agent, or run directly, e.g.
113 systemctl start corosync dlm
114 5. create VG on shared devices
117 vgcreate --shared <vgname> <devices>
118 The shared option sets the VG lock type to sanlock or dlm depending on
120 which lock manager is running. LVM commands acquire locks from lvm‐
121 lockd, and lvmlockd uses the chosen lock manager.
122 6. start VG on all hosts
125 vgchange --lock-start
126 Shared VGs must be started before they are used. Starting the VG per‐
128 forms lock manager initialization that is necessary to begin using
129 locks (i.e. creating and joining a lockspace). Starting the VG may
130 take some time, and until the start completes the VG may not be modi‐
131 fied or activated.
132 7. create and activate LVs
135 Standard lvcreate and lvchange commands are used to create and activate
136 LVs in a shared VG.
137 An LV activated exclusively on one host cannot be activated on another.
139 When multiple hosts need to use the same LV concurrently, the LV can be
140 activated with a shared lock (see lvchange options -aey vs -asy.)
141 (Shared locks are disallowed for certain LV types that cannot be used
142 from multiple hosts.)
143 Normal start up and shut down
147 After initial set up, start up and shut down include the following
148 steps. They can be performed directly or may be automated using sys‐
149 temd or a cluster resource manager/agents.
150 · start lvmlockd
152 · start lock manager
153 · vgchange --lock-start
154 · activate LVs in shared VGs
155 The shut down sequence is the reverse:
157 · deactivate LVs in shared VGs
159 · vgchange --lock-stop
160 · stop lock manager
161 · stop lvmlockd
162
165 Protecting VGs on shared devices
166 The following terms are used to describe the different ways of access‐
167 ing VGs on shared devices.
168 shared VG
170 A shared VG exists on shared storage that is visible to multiple hosts.
172 LVM acquires locks through lvmlockd to coordinate access to shared VGs.
173 A shared VG has lock_type "dlm" or "sanlock", which specifies the lock
174 manager lvmlockd will use.
175 When the lock manager for the lock type is not available (e.g. not
177 started or failed), lvmlockd is unable to acquire locks for LVM com‐
178 mands. In this situation, LVM commands are only allowed to read and
179 display the VG; changes and activation will fail.
180 local VG
182 A local VG is meant to be used by a single host. It has no lock type
184 or lock type "none". A local VG typically exists on local (non-shared)
185 devices and cannot be used concurrently from different hosts.
186 If a local VG does exist on shared devices, it should be owned by a
188 single host by having the system ID set, see lvmsystemid(7). The host
189 with a matching system ID can use the local VG and other hosts will
190 ignore it. A VG with no lock type and no system ID should be excluded
191 from all but one host using lvm.conf filters. Without any of these
192 protections, a local VG on shared devices can be easily damaged or
193 destroyed.
194 clvm VG
196 A clvm VG (or clustered VG) is a VG on shared storage (like a shared
198 VG) that requires clvmd for clustering and locking. See below for con‐
199 verting a clvm/clustered VG to a shared VG.
200 shared VGs from hosts not using lvmlockd
204 Hosts that do not use shared VGs will not be running lvmlockd. In this
205 case, shared VGs that are still visible to the host will be ignored
206 (like foreign VGs, see lvmsystemid(7).)
207 The --shared option for reporting and display commands causes shared
209 VGs to be displayed on a host not using lvmlockd, like the --foreign
210 option does for foreign VGs.
211 creating the first sanlock VG
215 Creating the first sanlock VG is not protected by locking, so it
216 requires special attention. This is because sanlock locks exist on
217 storage within the VG, so they are not available until after the VG is
218 created. The first sanlock VG that is created will automatically con‐
219 tain the "global lock". Be aware of the following special considera‐
220 tions:
221 · The first vgcreate command needs to be given the path to a device
224 that has not yet been initialized with pvcreate. The pvcreate ini‐
225 tialization will be done by vgcreate. This is because the pvcreate
226 command requires the global lock, which will not be available until
227 after the first sanlock VG is created.
228 · Because the first sanlock VG will contain the global lock, this VG
231 needs to be accessible to all hosts that will use sanlock shared VGs.
232 All hosts will need to use the global lock from the first sanlock VG.
233 · The device and VG name used by the initial vgcreate will not be pro‐
236 tected from concurrent use by another vgcreate on another host.
237 See below for more information about managing the sanlock global
239 lock.
240 using shared VGs
244 There are some special considerations when using shared VGs.
245 When use_lvmlockd is first enabled in lvm.conf, and before the first
247 shared VG is created, no global lock will exist. In this initial
248 state, LVM commands try and fail to acquire the global lock, producing
249 a warning, and some commands are disallowed. Once the first shared VG
250 is created, the global lock will be available, and LVM will be fully
251 operational.
252 When a new shared VG is created, its lockspace is automatically started
254 on the host that creates it. Other hosts need to run 'vgchange
255 --lock-start' to start the new VG before they can use it.
256 From the 'vgs' command, shared VGs are indicated by "s" (for shared) in
258 the sixth attr field, and by "shared" in the "--options shared" report
259 field. The specific lock type and lock args for a shared VG can be
260 displayed with 'vgs -o+locktype,lockargs'.
261 Shared VGs need to be "started" and "stopped", unlike other types of
263 VGs. See the following section for a full description of starting and
264 stopping.
265 Removing a shared VG will fail if other hosts have the VG started. Run
267 vgchange --lock-stop <vgname> on all other hosts before vgremove. (It
268 may take several seconds before vgremove recognizes that all hosts have
269 stopped a sanlock VG.)
270 starting and stopping VGs
273 Starting a shared VG (vgchange --lock-start) causes the lock manager to
274 start (join) the lockspace for the VG on the host where it is run.
275 This makes locks for the VG available to LVM commands on the host.
276 Before a VG is started, only LVM commands that read/display the VG are
277 allowed to continue without locks (and with a warning).
278 Stopping a shared VG (vgchange --lock-stop) causes the lock manager to
280 stop (leave) the lockspace for the VG on the host where it is run.
281 This makes locks for the VG inaccessible to the host. A VG cannot be
282 stopped while it has active LVs.
283 When using the lock type sanlock, starting a VG can take a long time
285 (potentially minutes if the host was previously shut down without
286 cleanly stopping the VG.)
287 A shared VG can be started after all the following are true:
289 · lvmlockd is running
290 · the lock manager is running
291 · the VG's devices are visible on the system
292 A shared VG can be stopped if all LVs are deactivated.
294 All shared VGs can be started/stopped using:
296 vgchange --lock-start
297 vgchange --lock-stop
298 Individual VGs can be started/stopped using:
301 vgchange --lock-start <vgname> ...
302 vgchange --lock-stop <vgname> ...
303 To make vgchange not wait for start to complete:
305 vgchange --lock-start --lock-opt nowait ...
306 lvmlockd can be asked directly to stop all lockspaces:
308 lvmlockctl -S--stop-lockspaces
309 To start only selected shared VGs, use the lvm.conf activa‐
311 tion/lock_start_list. When defined, only VG names in this list are
312 started by vgchange. If the list is not defined (the default), all
313 visible shared VGs are started. To start only "vg1", use the following
314 lvm.conf configuration:
315 activation {
317 lock_start_list = [ "vg1" ]
318 ...
319 }
320 automatic starting and automatic activation
324 When system-level scripts/programs automatically start VGs, they should
325 use the "auto" option. This option indicates that the command is being
326 run automatically by the system:
327 vgchange --lock-start --lock-opt auto [<vgname> ...]
329 The "auto" option causes the command to follow the lvm.conf activa‐
331 tion/auto_lock_start_list. If auto_lock_start_list is undefined, all
332 VGs are started, just as if the auto option was not used.
333 When auto_lock_start_list is defined, it lists the shared VGs that
335 should be started by the auto command. VG names that do not match an
336 item in the list will be ignored by the auto start command.
337 (The lock_start_list is also still used to filter VG names from all
339 start commands, i.e. with or without the auto option. When the
340 lock_start_list is defined, only VGs matching a list item can be
341 started with vgchange.)
342 The auto_lock_start_list allows a user to select certain shared VGs
344 that should be automatically started by the system (or indirectly,
345 those that should not).
346 internal command locking
350 To optimize the use of LVM with lvmlockd, be aware of the three kinds
351 of locks and when they are used:
352 Global lock
354 The global lock s associated with global information, which is informa‐
356 tion not isolated to a single VG. This includes:
357 · The global VG namespace.
359 · The set of orphan PVs and unused devices.
360 · The properties of orphan PVs, e.g. PV size.
361 The global lock is acquired in shared mode by commands that read this
363 information, or in exclusive mode by commands that change it. For
364 example, the command 'vgs' acquires the global lock in shared mode
365 because it reports the list of all VG names, and the vgcreate command
366 acquires the global lock in exclusive mode because it creates a new VG
367 name, and it takes a PV from the list of unused PVs.
368 When an LVM command is given a tag argument, or uses select, it must
370 read all VGs to match the tag or selection, which causes the global
371 lock to be acquired.
372 VG lock
374 A VG lock is associated with each shared VG. The VG lock is acquired
376 in shared mode to read the VG and in exclusive mode to change the VG or
377 activate LVs. This lock serializes access to a VG with all other LVM
378 commands accessing the VG from all hosts.
379 The command 'vgs <vgname>' does not acquire the global lock (it does
381 not need the list of all VG names), but will acquire the VG lock on
382 each VG name argument.
383 LV lock
385 An LV lock is acquired before the LV is activated, and is released
387 after the LV is deactivated. If the LV lock cannot be acquired, the LV
388 is not activated. (LV locks are persistent and remain in place when
389 the activation command is done. Global and VG locks are transient, and
390 are held only while an LVM command is running.)
391 lock retries
393 If a request for a Global or VG lock fails due to a lock conflict with
395 another host, lvmlockd automatically retries for a short time before
396 returning a failure to the LVM command. If those retries are insuffi‐
397 cient, the LVM command will retry the entire lock request a number of
398 times specified by global/lvmlockd_lock_retries before failing. If a
399 request for an LV lock fails due to a lock conflict, the command fails
400 immediately.
401 managing the global lock in sanlock VGs
405 The global lock exists in one of the sanlock VGs. The first sanlock VG
406 created will contain the global lock. Subsequent sanlock VGs will each
407 contain a disabled global lock that can be enabled later if necessary.
408 The VG containing the global lock must be visible to all hosts using
410 sanlock VGs. For this reason, it can be useful to create a small san‐
411 lock VG, visible to all hosts, and dedicated to just holding the global
412 lock. While not required, this strategy can help to avoid difficulty
413 in the future if VGs are moved or removed.
414 The vgcreate command typically acquires the global lock, but in the
416 case of the first sanlock VG, there will be no global lock to acquire
417 until the first vgcreate is complete. So, creating the first sanlock
418 VG is a special case that skips the global lock.
419 vgcreate determines that it's creating the first sanlock VG when no
421 other sanlock VGs are visible on the system. It is possible that other
422 sanlock VGs do exist, but are not visible when vgcreate checks for
423 them. In this case, vgcreate will create a new sanlock VG with the
424 global lock enabled. When the another VG containing a global lock
425 appears, lvmlockd will then see more than one VG with a global lock
426 enabled. LVM commands will report that there are duplicate global
427 locks.
428 If the situation arises where more than one sanlock VG contains a
430 global lock, the global lock should be manually disabled in all but one
431 of them with the command:
432 lvmlockctl --gl-disable <vgname>
434 (The one VG with the global lock enabled must be visible to all hosts.)
436 An opposite problem can occur if the VG holding the global lock is
438 removed. In this case, no global lock will exist following the vgre‐
439 move, and subsequent LVM commands will fail to acquire it. In this
440 case, the global lock needs to be manually enabled in one of the
441 remaining sanlock VGs with the command:
442 lvmlockctl --gl-enable <vgname>
444 (Using a small sanlock VG dedicated to holding the global lock can
446 avoid the case where the global lock must be manually enabled after a
447 vgremove.)
448 internal lvmlock LV
452 A sanlock VG contains a hidden LV called "lvmlock" that holds the san‐
453 lock locks. vgreduce cannot yet remove the PV holding the lvmlock LV.
454 To remove this PV, change the VG lock type to "none", run vgreduce,
455 then change the VG lock type back to "sanlock". Similarly, pvmove can‐
456 not be used on a PV used by the lvmlock LV.
457 To place the lvmlock LV on a specific device, create the VG with only
459 that device, then use vgextend to add other devices.
460 LV activation
464 In a shared VG, LV activation involves locking through lvmlockd, and
465 the following values are possible with lvchange/vgchange -a:
466 y|ey The command activates the LV in exclusive mode, allowing a sin‐
469 gle host to activate the LV. Before activating the LV, the com‐
470 mand uses lvmlockd to acquire an exclusive lock on the LV. If
471 the lock cannot be acquired, the LV is not activated and an
472 error is reported. This would happen if the LV is active on
473 another host.
474 sy The command activates the LV in shared mode, allowing multiple
477 hosts to activate the LV concurrently. Before activating the
478 LV, the command uses lvmlockd to acquire a shared lock on the
479 LV. If the lock cannot be acquired, the LV is not activated and
480 an error is reported. This would happen if the LV is active
481 exclusively on another host. If the LV type prohibits shared
482 access, such as a snapshot, the command will report an error and
483 fail. The shared mode is intended for a multi-host/cluster
484 application or file system. LV types that cannot be used con‐
485 currently from multiple hosts include thin, cache, raid, and
486 snapshot.
487 n The command deactivates the LV. After deactivating the LV, the
490 command uses lvmlockd to release the current lock on the LV.
491 manually repairing a shared VG
495 Some failure conditions may not be repairable while the VG has a shared
496 lock type. In these cases, it may be possible to repair the VG by
497 forcibly changing the lock type to "none". This is done by adding
498 "--lock-opt force" to the normal command for changing the lock type:
499 vgchange --lock-type none VG. The VG lockspace should first be stopped
500 on all hosts, and be certain that no hosts are using the VG before this
501 is done.
502 recover from lost PV holding sanlock locks
506 In a sanlock VG, the sanlock locks are held on the hidden "lvmlock" LV.
507 If the PV holding this LV is lost, a new lvmlock LV needs to be cre‐
508 ated. To do this, ensure no hosts are using the VG, then forcibly
509 change the lock type to "none" (see above). Then change the lock type
510 back to "sanlock" with the normal command for changing the lock type:
511 vgchange --lock-type sanlock VG. This recreates the internal lvmlock
512 LV with the necessary locks.
513 locking system failures
517 lvmlockd failure
518 If lvmlockd fails or is killed while holding locks, the locks are
520 orphaned in the lock manager. lvmlockd can be restarted with an option
521 to adopt locks in the lock manager that had been held by the previous
522 instance.
523 dlm/corosync failure
525 If dlm or corosync fail, the clustering system will fence the host
527 using a method configured within the dlm/corosync clustering environ‐
528 ment.
529 LVM commands on other hosts will be blocked from acquiring any locks
531 until the dlm/corosync recovery process is complete.
532 sanlock lease storage failure
534 If the PV under a sanlock VG's lvmlock LV is disconnected, unresponsive
536 or too slow, sanlock cannot renew the lease for the VG's locks. After
537 some time, the lease will expire, and locks that the host owns in the
538 VG can be acquired by other hosts. The VG must be forcibly deactivated
539 on the host with the expiring lease before other hosts can acquire its
540 locks.
541 When the sanlock daemon detects that the lease storage is lost, it runs
543 the command lvmlockctl --kill <vgname>. This command emits a syslog
544 message stating that lease storage is lost for the VG, and LVs must be
545 immediately deactivated.
546 If no LVs are active in the VG, then the lockspace with an expiring
548 lease will be removed, and errors will be reported when trying to use
549 the VG. Use the lvmlockctl --drop command to clear the stale lockspace
550 from lvmlockd.
551 If the VG has active LVs when the lock storage is lost, the LVs must be
553 quickly deactivated before the lockspace lease expires. After all LVs
554 are deactivated, run lvmlockctl --drop <vgname> to clear the expiring
555 lockspace from lvmlockd. If all LVs in the VG are not deactivated
556 within about 40 seconds, sanlock uses wdmd and the local watchdog to
557 reset the host. The machine reset is effectively a severe form of
558 "deactivating" LVs before they can be activated on other hosts. The
559 reset is considered a better alternative than having LVs used by multi‐
560 ple hosts at once, which could easily damage or destroy their content.
561 In the future, the lvmlockctl kill command may automatically attempt to
563 forcibly deactivate LVs before the sanlock lease expires. Until then,
564 the user must notice the syslog message and manually deactivate the VG
565 before sanlock resets the machine.
566 sanlock daemon failure
568 If the sanlock daemon fails or exits while a lockspace is started, the
570 local watchdog will reset the host. This is necessary to protect any
571 application resources that depend on sanlock leases.
572 changing dlm cluster name
576 When a dlm VG is created, the cluster name is saved in the VG metadata.
577 To use the VG, a host must be in the named dlm cluster. If the dlm
578 cluster name changes, or the VG is moved to a new cluster, the dlm
579 cluster name saved in the VG must also be changed.
580 To see the dlm cluster name saved in the VG, use the command:
582 vgs -o+locktype,lockargs <vgname>
583 To change the dlm cluster name in the VG when the VG is still used by
585 the original cluster:
586 · Start the VG on the host changing the lock type
589 vgchange --lock-start <vgname>
590 · Stop the VG on all other hosts:
593 vgchange --lock-stop <vgname>
594 · Change the VG lock type to none on the host where the VG is started:
597 vgchange --lock-type none <vgname>
598 · Change the dlm cluster name on the hosts or move the VG to the new
601 cluster. The new dlm cluster must now be running on the host. Ver‐
602 ify the new name by:
603 cat /sys/kernel/config/dlm/cluster/cluster_name
604 · Change the VG lock type back to dlm which sets the new cluster name:
607 vgchange --lock-type dlm <vgname>
608 · Start the VG on hosts to use it:
611 vgchange --lock-start <vgname>
612 To change the dlm cluster name in the VG when the dlm cluster name has
615 already been changed on the hosts, or the VG has already moved to a
616 different cluster:
617 · Ensure the VG is not being used by any hosts.
620 · The new dlm cluster must be running on the host making the change.
623 The current dlm cluster name can be seen by:
624 cat /sys/kernel/config/dlm/cluster/cluster_name
625 · Change the VG lock type to none:
628 vgchange --lock-type none --lock-opt force <vgname>
629 · Change the VG lock type back to dlm which sets the new cluster name:
632 vgchange --lock-type dlm <vgname>
633 · Start the VG on hosts to use it:
636 vgchange --lock-start <vgname>
637 changing a local VG to a shared VG
641 All LVs must be inactive to change the lock type.
642 lvmlockd must be configured and running as described in USAGE.
644 · Change a local VG to a shared VG with the command:
647 vgchange --lock-type sanlock|dlm <vgname>
648 · Start the VG on hosts to use it:
651 vgchange --lock-start <vgname>
652 changing a shared VG to a local VG
655 All LVs must be inactive to change the lock type.
656 · Start the VG on the host making the change:
659 vgchange --lock-start <vgname>
660 · Stop the VG on all other hosts:
663 vgchange --lock-stop <vgname>
664 · Change the VG lock type to none on the host where the VG is started:
667 vgchange --lock-type none <vgname>
668 If the VG cannot be started with the previous lock type, then the lock
671 type can be forcibly changed to none with:
672 vgchange --lock-type none --lock-opt force <vgname>
674 To change a VG from one lock type to another (i.e. between sanlock and
676 dlm), first change it to a local VG, then to the new type.
677 changing a clvm/clustered VG to a shared VG
681 All LVs must be inactive to change the lock type.
682 First change the clvm/clustered VG to a local VG. Within a running
684 clvm cluster, change a clustered VG to a local VG with the command:
685 vgchange -cn <vgname>
687 If the clvm cluster is no longer running on any nodes, then extra
689 options can be used to forcibly make the VG local. Caution: this is
690 only safe if all nodes have stopped using the VG:
691 vgchange --lock-type none --lock-opt force <vgname>
693 After the VG is local, follow the steps described in "changing a local
695 VG to a shared VG".
696 limitations of shared VGs
700 Things that do not yet work in shared VGs:
701 · using external origins for thin LVs
702 · splitting snapshots from LVs
703 · splitting mirrors in sanlock VGs
704 · pvmove of entire PVs, or under LVs activated with shared locks
705 · vgsplit and vgmerge (convert to a local VG to do this)
706 lvmlockd changes from clvmd
710 (See above for converting an existing clvm VG to a shared VG.)
711 While lvmlockd and clvmd are entirely different systems, LVM command
713 usage remains similar. Differences are more notable when using lvm‐
714 lockd's sanlock option.
715 Visible usage differences between shared VGs (using lvmlockd) and
717 clvm/clustered VGs (using clvmd):
718 · lvm.conf must be configured to use either lvmlockd (use_lvmlockd=1)
721 or clvmd (locking_type=3), but not both.
722 · vgcreate --shared creates a shared VG, and vgcreate --clustered y
725 creates a clvm/clustered VG.
726 · lvmlockd adds the option of using sanlock for locking, avoiding the
729 need for network clustering.
730 · lvmlockd defaults to the exclusive activation mode whenever the acti‐
733 vation mode is unspecified, i.e. -ay means -aey, not -asy.
734 · lvmlockd commands always apply to the local host, and never have an
737 effect on a remote host. (The activation option 'l' is not used.)
738 · lvmlockd works with thin and cache pools and LVs.
741 · lvmlockd works with lvmetad.
744 · lvmlockd saves the cluster name for a shared VG using dlm. Only
747 hosts in the matching cluster can use the VG.
748 · lvmlockd requires starting/stopping shared VGs with vgchange
751 --lock-start and --lock-stop.
752 · vgremove of a sanlock VG may fail indicating that all hosts have not
755 stopped the VG lockspace. Stop the VG on all hosts using vgchange
756 --lock-stop.
757 · vgreduce or pvmove of a PV in a sanlock VG will fail if it holds the
760 internal "lvmlock" LV that holds the sanlock locks.
761 · lvmlockd uses lock retries instead of lock queueing, so high lock
764 contention may require increasing global/lvmlockd_lock_retries to
765 avoid transient lock failures.
766 · lvmlockd includes VG reporting options lock_type and lock_args, and
769 LV reporting option lock_args to view the corresponding metadata
770 fields.
771 · In the 'vgs' command's sixth VG attr field, "s" for "shared" is dis‐
774 played for shared VGs.
775 · If lvmlockd fails or is killed while in use, locks it held remain but
778 are orphaned in the lock manager. lvmlockd can be restarted with an
779 option to adopt the orphan locks from the previous instance of lvm‐
780 lockd.
781Red Hat, Inc LVM TOOLS 2.02.180(2)-RHEL7 (2018-07-20) LVMLOCKD(8)