1CTDB(7)                  CTDB - clustered TDB database                 CTDB(7)
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NAME

6       ctdb - Clustered TDB
7

DESCRIPTION

9       CTDB is a clustered database component in clustered Samba that provides
10       a high-availability load-sharing CIFS server cluster.
11
12       The main functions of CTDB are:
13
14       •   Provide a clustered version of the TDB database with automatic
15           rebuild/recovery of the databases upon node failures.
16
17       •   Monitor nodes in the cluster and services running on each node.
18
19       •   Manage a pool of public IP addresses that are used to provide
20           services to clients. Alternatively, CTDB can be used with LVS.
21
22       Combined with a cluster filesystem CTDB provides a full
23       high-availablity (HA) environment for services such as clustered Samba,
24       NFS and other services.
25
26       In addition to the CTDB manual pages there is much more information
27       available at https://wiki.samba.org/index.php/CTDB_and_Clustered_Samba.
28

ANATOMY OF A CTDB CLUSTER

30       A CTDB cluster is a collection of nodes with 2 or more network
31       interfaces. All nodes provide network (usually file/NAS) services to
32       clients. Data served by file services is stored on shared storage
33       (usually a cluster filesystem) that is accessible by all nodes.
34
35       CTDB provides an "all active" cluster, where services are load balanced
36       across all nodes.
37

RECOVERY LOCK

39       CTDB uses a recovery lock to avoid a split brain, where a cluster
40       becomes partitioned and each partition attempts to operate
41       independently. Issues that can result from a split brain include file
42       data corruption, because file locking metadata may not be tracked
43       correctly.
44
45       CTDB uses a cluster leader and follower model of cluster management.
46       All nodes in a cluster elect one node to be the leader. The leader node
47       coordinates privileged operations such as database recovery and IP
48       address failover. CTDB refers to the leader node as the recovery
49       master. This node takes and holds the recovery lock to assert its
50       privileged role in the cluster.
51
52       By default, the recovery lock is implemented using a file (specified by
53       recovery lock in the [cluster] section of ctdb.conf(5)) residing in
54       shared storage (usually) on a cluster filesystem. To support a recovery
55       lock the cluster filesystem must support lock coherence. See
56       ping_pong(1) for more details.
57
58       The recovery lock can also be implemented using an arbitrary cluster
59       mutex helper (or call-out). This is indicated by using an exclamation
60       point ('!') as the first character of the recovery lock parameter. For
61       example, a value of !/usr/bin/myhelper recovery would run the given
62       helper with the specified arguments. The helper will continue to run as
63       long as it holds its mutex. See ctdb/doc/cluster_mutex_helper.txt in
64       the source tree, and related code, for clues about writing helpers.
65
66       When a file is specified for the recovery lock parameter (i.e. no
67       leading '!') the file lock is implemented by a default helper
68       (/usr/libexec/ctdb/ctdb_mutex_fcntl_helper). This helper has arguments
69       as follows:
70
71
72           ctdb_mutex_fcntl_helper FILE [RECHECK-INTERVAL]
73
74
75
76       ctdb_mutex_fcntl_helper will take a lock on FILE and then check every
77       RECHECK-INTERVAL seconds to ensure that FILE still exists and that its
78       inode number is unchanged from when the lock was taken. The default
79       value for RECHECK-INTERVAL is 5.
80
81       If a cluster becomes partitioned (for example, due to a communication
82       failure) and a different recovery master is elected by the nodes in
83       each partition, then only one of these recovery masters will be able to
84       take the recovery lock. The recovery master in the "losing" partition
85       will not be able to take the recovery lock and will be excluded from
86       the cluster. The nodes in the "losing" partition will elect each node
87       in turn as their recovery master so eventually all the nodes in that
88       partition will be excluded.
89
90       CTDB does sanity checks to ensure that the recovery lock is held as
91       expected.
92
93       CTDB can run without a recovery lock but this is not recommended as
94       there will be no protection from split brains.
95

PRIVATE VS PUBLIC ADDRESSES

97       Each node in a CTDB cluster has multiple IP addresses assigned to it:
98
99       •   A single private IP address that is used for communication between
100           nodes.
101
102       •   One or more public IP addresses that are used to provide NAS or
103           other services.
104
105
106   Private address
107       Each node is configured with a unique, permanently assigned private
108       address. This address is configured by the operating system. This
109       address uniquely identifies a physical node in the cluster and is the
110       address that CTDB daemons will use to communicate with the CTDB daemons
111       on other nodes.
112
113       Private addresses are listed in the file /etc/ctdb/nodes). This file
114       contains the list of private addresses for all nodes in the cluster,
115       one per line. This file must be the same on all nodes in the cluster.
116
117       Some users like to put this configuration file in their cluster
118       filesystem. A symbolic link should be used in this case.
119
120       Private addresses should not be used by clients to connect to services
121       provided by the cluster.
122
123       It is strongly recommended that the private addresses are configured on
124       a private network that is separate from client networks. This is
125       because the CTDB protocol is both unauthenticated and unencrypted. If
126       clients share the private network then steps need to be taken to stop
127       injection of packets to relevant ports on the private addresses. It is
128       also likely that CTDB protocol traffic between nodes could leak
129       sensitive information if it can be intercepted.
130
131       Example /etc/ctdb/nodes for a four node cluster:
132
133           192.168.1.1
134           192.168.1.2
135           192.168.1.3
136           192.168.1.4
137
138
139   Public addresses
140       Public addresses are used to provide services to clients. Public
141       addresses are not configured at the operating system level and are not
142       permanently associated with a particular node. Instead, they are
143       managed by CTDB and are assigned to interfaces on physical nodes at
144       runtime.
145
146       The CTDB cluster will assign/reassign these public addresses across the
147       available healthy nodes in the cluster. When one node fails, its public
148       addresses will be taken over by one or more other nodes in the cluster.
149       This ensures that services provided by all public addresses are always
150       available to clients, as long as there are nodes available capable of
151       hosting this address.
152
153       The public address configuration is stored in
154       /etc/ctdb/public_addresses on each node. This file contains a list of
155       the public addresses that the node is capable of hosting, one per line.
156       Each entry also contains the netmask and the interface to which the
157       address should be assigned. If this file is missing then no public
158       addresses are configured.
159
160       Some users who have the same public addresses on all nodes like to put
161       this configuration file in their cluster filesystem. A symbolic link
162       should be used in this case.
163
164       Example /etc/ctdb/public_addresses for a node that can host 4 public
165       addresses, on 2 different interfaces:
166
167           10.1.1.1/24 eth1
168           10.1.1.2/24 eth1
169           10.1.2.1/24 eth2
170           10.1.2.2/24 eth2
171
172
173       In many cases the public addresses file will be the same on all nodes.
174       However, it is possible to use different public address configurations
175       on different nodes.
176
177       Example: 4 nodes partitioned into two subgroups:
178
179           Node 0:/etc/ctdb/public_addresses
180                10.1.1.1/24 eth1
181                10.1.1.2/24 eth1
182
183           Node 1:/etc/ctdb/public_addresses
184                10.1.1.1/24 eth1
185                10.1.1.2/24 eth1
186
187           Node 2:/etc/ctdb/public_addresses
188                10.1.2.1/24 eth2
189                10.1.2.2/24 eth2
190
191           Node 3:/etc/ctdb/public_addresses
192                10.1.2.1/24 eth2
193                10.1.2.2/24 eth2
194
195
196       In this example nodes 0 and 1 host two public addresses on the 10.1.1.x
197       network while nodes 2 and 3 host two public addresses for the 10.1.2.x
198       network.
199
200       Public address 10.1.1.1 can be hosted by either of nodes 0 or 1 and
201       will be available to clients as long as at least one of these two nodes
202       are available.
203
204       If both nodes 0 and 1 become unavailable then public address 10.1.1.1
205       also becomes unavailable. 10.1.1.1 can not be failed over to nodes 2 or
206       3 since these nodes do not have this public address configured.
207
208       The ctdb ip command can be used to view the current assignment of
209       public addresses to physical nodes.
210

NODE STATUS

212       The current status of each node in the cluster can be viewed by the
213       ctdb status command.
214
215       A node can be in one of the following states:
216
217       OK
218           This node is healthy and fully functional. It hosts public
219           addresses to provide services.
220
221       DISCONNECTED
222           This node is not reachable by other nodes via the private network.
223           It is not currently participating in the cluster. It does not host
224           public addresses to provide services. It might be shut down.
225
226       DISABLED
227           This node has been administratively disabled. This node is
228           partially functional and participates in the cluster. However, it
229           does not host public addresses to provide services.
230
231       UNHEALTHY
232           A service provided by this node has failed a health check and
233           should be investigated. This node is partially functional and
234           participates in the cluster. However, it does not host public
235           addresses to provide services. Unhealthy nodes should be
236           investigated and may require an administrative action to rectify.
237
238       BANNED
239           CTDB is not behaving as designed on this node. For example, it may
240           have failed too many recovery attempts. Such nodes are banned from
241           participating in the cluster for a configurable time period before
242           they attempt to rejoin the cluster. A banned node does not host
243           public addresses to provide services. All banned nodes should be
244           investigated and may require an administrative action to rectify.
245
246       STOPPED
247           This node has been administratively exclude from the cluster. A
248           stopped node does no participate in the cluster and does not host
249           public addresses to provide services. This state can be used while
250           performing maintenance on a node.
251
252       PARTIALLYONLINE
253           A node that is partially online participates in a cluster like a
254           healthy (OK) node. Some interfaces to serve public addresses are
255           down, but at least one interface is up. See also ctdb ifaces.
256

CAPABILITIES

258       Cluster nodes can have several different capabilities enabled. These
259       are listed below.
260
261       RECMASTER
262           Indicates that a node can become the CTDB cluster recovery master.
263           The current recovery master is decided via an election held by all
264           active nodes with this capability.
265
266           Default is YES.
267
268       LMASTER
269           Indicates that a node can be the location master (LMASTER) for
270           database records. The LMASTER always knows which node has the
271           latest copy of a record in a volatile database.
272
273           Default is YES.
274
275       The RECMASTER and LMASTER capabilities can be disabled when CTDB is
276       used to create a cluster spanning across WAN links. In this case CTDB
277       acts as a WAN accelerator.
278

LVS

280       LVS is a mode where CTDB presents one single IP address for the entire
281       cluster. This is an alternative to using public IP addresses and
282       round-robin DNS to loadbalance clients across the cluster.
283
284       This is similar to using a layer-4 loadbalancing switch but with some
285       restrictions.
286
287       One extra LVS public address is assigned on the public network to each
288       LVS group. Each LVS group is a set of nodes in the cluster that
289       presents the same LVS address public address to the outside world.
290       Normally there would only be one LVS group spanning an entire cluster,
291       but in situations where one CTDB cluster spans multiple physical sites
292       it might be useful to have one LVS group for each site. There can be
293       multiple LVS groups in a cluster but each node can only be member of
294       one LVS group.
295
296       Client access to the cluster is load-balanced across the HEALTHY nodes
297       in an LVS group. If no HEALTHY nodes exists then all nodes in the group
298       are used, regardless of health status. CTDB will, however never
299       load-balance LVS traffic to nodes that are BANNED, STOPPED, DISABLED or
300       DISCONNECTED. The ctdb lvs command is used to show which nodes are
301       currently load-balanced across.
302
303       In each LVS group, one of the nodes is selected by CTDB to be the LVS
304       leader. This node receives all traffic from clients coming in to the
305       LVS public address and multiplexes it across the internal network to
306       one of the nodes that LVS is using. When responding to the client, that
307       node will send the data back directly to the client, bypassing the LVS
308       leader node. The command ctdb lvs leader will show which node is the
309       current LVS leader.
310
311       The path used for a client I/O is:
312
313        1. Client sends request packet to LVS leader.
314
315        2. LVS leader passes the request on to one node across the internal
316           network.
317
318        3. Selected node processes the request.
319
320        4. Node responds back to client.
321
322       This means that all incoming traffic to the cluster will pass through
323       one physical node, which limits scalability. You can send more data to
324       the LVS address that one physical node can multiplex. This means that
325       you should not use LVS if your I/O pattern is write-intensive since you
326       will be limited in the available network bandwidth that node can
327       handle. LVS does work very well for read-intensive workloads where only
328       smallish READ requests are going through the LVS leader bottleneck and
329       the majority of the traffic volume (the data in the read replies) goes
330       straight from the processing node back to the clients. For
331       read-intensive i/o patterns you can achieve very high throughput rates
332       in this mode.
333
334       Note: you can use LVS and public addresses at the same time.
335
336       If you use LVS, you must have a permanent address configured for the
337       public interface on each node. This address must be routable and the
338       cluster nodes must be configured so that all traffic back to client
339       hosts are routed through this interface. This is also required in order
340       to allow samba/winbind on the node to talk to the domain controller.
341       This LVS IP address can not be used to initiate outgoing traffic.
342
343       Make sure that the domain controller and the clients are reachable from
344       a node before you enable LVS. Also ensure that outgoing traffic to
345       these hosts is routed out through the configured public interface.
346
347   Configuration
348       To activate LVS on a CTDB node you must specify the
349       CTDB_LVS_PUBLIC_IFACE, CTDB_LVS_PUBLIC_IP and CTDB_LVS_NODES
350       configuration variables.  CTDB_LVS_NODES specifies a file containing
351       the private address of all nodes in the current node's LVS group.
352
353       Example:
354
355           CTDB_LVS_PUBLIC_IFACE=eth1
356           CTDB_LVS_PUBLIC_IP=10.1.1.237
357           CTDB_LVS_NODES=/etc/ctdb/lvs_nodes
358
359
360       Example /etc/ctdb/lvs_nodes:
361
362           192.168.1.2
363           192.168.1.3
364           192.168.1.4
365
366
367       Normally any node in an LVS group can act as the LVS leader. Nodes that
368       are highly loaded due to other demands maybe flagged with the
369       "follower-only" option in the CTDB_LVS_NODES file to limit the LVS
370       functionality of those nodes.
371
372       LVS nodes file that excludes 192.168.1.4 from being the LVS leader
373       node:
374
375           192.168.1.2
376           192.168.1.3
377           192.168.1.4 follower-only
378
379

TRACKING AND RESETTING TCP CONNECTIONS

381       CTDB tracks TCP connections from clients to public IP addresses, on
382       known ports. When an IP address moves from one node to another, all
383       existing TCP connections to that IP address are reset. The node taking
384       over this IP address will also send gratuitous ARPs (for IPv4, or
385       neighbour advertisement, for IPv6). This allows clients to reconnect
386       quickly, rather than waiting for TCP timeouts, which can be very long.
387
388       It is important that established TCP connections do not survive a
389       release and take of a public IP address on the same node. Such
390       connections can get out of sync with sequence and ACK numbers,
391       potentially causing a disruptive ACK storm.
392

NAT GATEWAY

394       NAT gateway (NATGW) is an optional feature that is used to configure
395       fallback routing for nodes. This allows cluster nodes to connect to
396       external services (e.g. DNS, AD, NIS and LDAP) when they do not host
397       any public addresses (e.g. when they are unhealthy).
398
399       This also applies to node startup because CTDB marks nodes as UNHEALTHY
400       until they have passed a "monitor" event. In this context, NAT gateway
401       helps to avoid a "chicken and egg" situation where a node needs to
402       access an external service to become healthy.
403
404       Another way of solving this type of problem is to assign an extra
405       static IP address to a public interface on every node. This is simpler
406       but it uses an extra IP address per node, while NAT gateway generally
407       uses only one extra IP address.
408
409   Operation
410       One extra NATGW public address is assigned on the public network to
411       each NATGW group. Each NATGW group is a set of nodes in the cluster
412       that shares the same NATGW address to talk to the outside world.
413       Normally there would only be one NATGW group spanning an entire
414       cluster, but in situations where one CTDB cluster spans multiple
415       physical sites it might be useful to have one NATGW group for each
416       site.
417
418       There can be multiple NATGW groups in a cluster but each node can only
419       be member of one NATGW group.
420
421       In each NATGW group, one of the nodes is selected by CTDB to be the
422       NATGW leader and the other nodes are consider to be NATGW followers.
423       NATGW followers establish a fallback default route to the NATGW leader
424       via the private network. When a NATGW follower hosts no public IP
425       addresses then it will use this route for outbound connections. The
426       NATGW leader hosts the NATGW public IP address and routes outgoing
427       connections from follower nodes via this IP address. It also
428       establishes a fallback default route.
429
430   Configuration
431       NATGW is usually configured similar to the following example
432       configuration:
433
434           CTDB_NATGW_NODES=/etc/ctdb/natgw_nodes
435           CTDB_NATGW_PRIVATE_NETWORK=192.168.1.0/24
436           CTDB_NATGW_PUBLIC_IP=10.0.0.227/24
437           CTDB_NATGW_PUBLIC_IFACE=eth0
438           CTDB_NATGW_DEFAULT_GATEWAY=10.0.0.1
439
440
441       Normally any node in a NATGW group can act as the NATGW leader. Some
442       configurations may have special nodes that lack connectivity to a
443       public network. In such cases, those nodes can be flagged with the
444       "follower-only" option in the CTDB_NATGW_NODES file to limit the NATGW
445       functionality of those nodes.
446
447       See the NAT GATEWAY section in ctdb-script.options(5) for more details
448       of NATGW configuration.
449
450   Implementation details
451       When the NATGW functionality is used, one of the nodes is selected to
452       act as a NAT gateway for all the other nodes in the group when they
453       need to communicate with the external services. The NATGW leader is
454       selected to be a node that is most likely to have usable networks.
455
456       The NATGW leader hosts the NATGW public IP address CTDB_NATGW_PUBLIC_IP
457       on the configured public interfaces CTDB_NATGW_PUBLIC_IFACE and acts as
458       a router, masquerading outgoing connections from follower nodes via
459       this IP address. If CTDB_NATGW_DEFAULT_GATEWAY is set then it also
460       establishes a fallback default route to the configured this gateway
461       with a metric of 10. A metric 10 route is used so it can co-exist with
462       other default routes that may be available.
463
464       A NATGW follower establishes its fallback default route to the NATGW
465       leader via the private network CTDB_NATGW_PRIVATE_NETWORKwith a metric
466       of 10. This route is used for outbound connections when no other
467       default route is available because the node hosts no public addresses.
468       A metric 10 routes is used so that it can co-exist with other default
469       routes that may be available when the node is hosting public addresses.
470
471       CTDB_NATGW_STATIC_ROUTES can be used to have NATGW create more specific
472       routes instead of just default routes.
473
474       This is implemented in the 11.natgw eventscript. Please see the
475       eventscript file and the NAT GATEWAY section in ctdb-script.options(5)
476       for more details.
477

POLICY ROUTING

479       Policy routing is an optional CTDB feature to support complex network
480       topologies. Public addresses may be spread across several different
481       networks (or VLANs) and it may not be possible to route packets from
482       these public addresses via the system's default route. Therefore, CTDB
483       has support for policy routing via the 13.per_ip_routing eventscript.
484       This allows routing to be specified for packets sourced from each
485       public address. The routes are added and removed as CTDB moves public
486       addresses between nodes.
487
488   Configuration variables
489       There are 4 configuration variables related to policy routing:
490       CTDB_PER_IP_ROUTING_CONF, CTDB_PER_IP_ROUTING_RULE_PREF,
491       CTDB_PER_IP_ROUTING_TABLE_ID_LOW, CTDB_PER_IP_ROUTING_TABLE_ID_HIGH.
492       See the POLICY ROUTING section in ctdb-script.options(5) for more
493       details.
494
495   Configuration
496       The format of each line of CTDB_PER_IP_ROUTING_CONF is:
497
498           <public_address> <network> [ <gateway> ]
499
500
501       Leading whitespace is ignored and arbitrary whitespace may be used as a
502       separator. Lines that have a "public address" item that doesn't match
503       an actual public address are ignored. This means that comment lines can
504       be added using a leading character such as '#', since this will never
505       match an IP address.
506
507       A line without a gateway indicates a link local route.
508
509       For example, consider the configuration line:
510
511             192.168.1.99 192.168.1.1/24
512
513
514       If the corresponding public_addresses line is:
515
516             192.168.1.99/24     eth2,eth3
517
518
519       CTDB_PER_IP_ROUTING_RULE_PREF is 100, and CTDB adds the address to eth2
520       then the following routing information is added:
521
522             ip rule add from 192.168.1.99 pref 100 table ctdb.192.168.1.99
523             ip route add 192.168.1.0/24 dev eth2 table ctdb.192.168.1.99
524
525
526       This causes traffic from 192.168.1.1 to 192.168.1.0/24 go via eth2.
527
528       The ip rule command will show (something like - depending on other
529       public addresses and other routes on the system):
530
531             0:      from all lookup local
532             100:         from 192.168.1.99 lookup ctdb.192.168.1.99
533             32766:  from all lookup main
534             32767:  from all lookup default
535
536
537       ip route show table ctdb.192.168.1.99 will show:
538
539             192.168.1.0/24 dev eth2 scope link
540
541
542       The usual use for a line containing a gateway is to add a default route
543       corresponding to a particular source address. Consider this line of
544       configuration:
545
546             192.168.1.99 0.0.0.0/0 192.168.1.1
547
548
549       In the situation described above this will cause an extra routing
550       command to be executed:
551
552             ip route add 0.0.0.0/0 via 192.168.1.1 dev eth2 table ctdb.192.168.1.99
553
554
555       With both configuration lines, ip route show table ctdb.192.168.1.99
556       will show:
557
558             192.168.1.0/24 dev eth2 scope link
559             default via 192.168.1.1 dev eth2
560
561
562   Sample configuration
563       Here is a more complete example configuration.
564
565           /etc/ctdb/public_addresses:
566
567             192.168.1.98 eth2,eth3
568             192.168.1.99 eth2,eth3
569
570           /etc/ctdb/policy_routing:
571
572             192.168.1.98 192.168.1.0/24
573             192.168.1.98 192.168.200.0/24    192.168.1.254
574             192.168.1.98 0.0.0.0/0      192.168.1.1
575             192.168.1.99 192.168.1.0/24
576             192.168.1.99 192.168.200.0/24    192.168.1.254
577             192.168.1.99 0.0.0.0/0      192.168.1.1
578
579
580       The routes local packets as expected, the default route is as
581       previously discussed, but packets to 192.168.200.0/24 are routed via
582       the alternate gateway 192.168.1.254.
583

NOTIFICATIONS

585       When certain state changes occur in CTDB, it can be configured to
586       perform arbitrary actions via notifications. For example, sending SNMP
587       traps or emails when a node becomes unhealthy or similar.
588
589       The notification mechanism runs all executable files ending in
590       ".script" in /etc/ctdb/events/notification/, ignoring any failures and
591       continuing to run all files.
592
593       CTDB currently generates notifications after CTDB changes to these
594       states:
595           init
596           setup
597           startup
598           healthy
599           unhealthy
600

LOG LEVELS

602       Valid log levels, in increasing order of verbosity, are:
603           ERROR
604           WARNING
605           NOTICE
606           INFO
607           DEBUG
608

REMOTE CLUSTER NODES

610       It is possible to have a CTDB cluster that spans across a WAN link. For
611       example where you have a CTDB cluster in your datacentre but you also
612       want to have one additional CTDB node located at a remote branch site.
613       This is similar to how a WAN accelerator works but with the difference
614       that while a WAN-accelerator often acts as a Proxy or a MitM, in the
615       ctdb remote cluster node configuration the Samba instance at the remote
616       site IS the genuine server, not a proxy and not a MitM, and thus
617       provides 100% correct CIFS semantics to clients.
618
619       See the cluster as one single multihomed samba server where one of the
620       NICs (the remote node) is very far away.
621
622       NOTE: This does require that the cluster filesystem you use can cope
623       with WAN-link latencies. Not all cluster filesystems can handle
624       WAN-link latencies! Whether this will provide very good WAN-accelerator
625       performance or it will perform very poorly depends entirely on how
626       optimized your cluster filesystem is in handling high latency for data
627       and metadata operations.
628
629       To activate a node as being a remote cluster node you need to set the
630       following two parameters in /etc/ctdb/ctdb.conf for the remote node:
631
632           [legacy]
633             lmaster capability = false
634             recmaster capability = false
635
636
637       Verify with the command "ctdb getcapabilities" that that node no longer
638       has the recmaster or the lmaster capabilities.
639

SEE ALSO

641       ctdb(1), ctdbd(1), ctdbd_wrapper(1), ctdb_diagnostics(1), ltdbtool(1),
642       onnode(1), ping_pong(1), ctdb.conf(5), ctdb-script.options(5),
643       ctdb.sysconfig(5), ctdb-statistics(7), ctdb-tunables(7),
644       https://wiki.samba.org/index.php/CTDB_and_Clustered_Samba,
645       http://ctdb.samba.org/
646

AUTHOR

648       This documentation was written by Ronnie Sahlberg, Amitay Isaacs,
649       Martin Schwenke
650
652       Copyright © 2007 Andrew Tridgell, Ronnie Sahlberg
653
654       This program is free software; you can redistribute it and/or modify it
655       under the terms of the GNU General Public License as published by the
656       Free Software Foundation; either version 3 of the License, or (at your
657       option) any later version.
658
659       This program is distributed in the hope that it will be useful, but
660       WITHOUT ANY WARRANTY; without even the implied warranty of
661       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
662       General Public License for more details.
663
664       You should have received a copy of the GNU General Public License along
665       with this program; if not, see http://www.gnu.org/licenses.
666
667
668
669
670ctdb                              11/13/2021                           CTDB(7)
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