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1 <?xml version="1.0" encoding="iso-8859-1"?>
2 <!DOCTYPE refentry PUBLIC "-//Samba-Team//DTD DocBook V4.2-Based Variant V1.0//EN" "http://www.samba.org/samba/DTD/samba-doc">
3 <refentry id="ctdbd.1">
5 <refmeta>
6 <refentrytitle>ctdbd</refentrytitle>
7 <manvolnum>1</manvolnum>
8 <refmiscinfo class="source">ctdb</refmiscinfo>
9 <refmiscinfo class="manual">CTDB - clustered TDB database</refmiscinfo>
10 </refmeta>
13 <refnamediv>
14 <refname>ctdbd</refname>
15 <refpurpose>The CTDB cluster daemon</refpurpose>
16 </refnamediv>
18 <refsynopsisdiv>
19 <cmdsynopsis>
20 <command>ctdbd</command>
21 </cmdsynopsis>
23 <cmdsynopsis>
24 <command>ctdbd</command>
25 <arg choice="opt">-? --help</arg>
26 <arg choice="opt">-d --debug=<INTEGER></arg>
27 <arg choice="req">--dbdir=<directory></arg>
28 <arg choice="req">--dbdir-persistent=<directory></arg>
29 <arg choice="opt">--event-script-dir=<directory></arg>
30 <arg choice="opt">-i --interactive</arg>
31 <arg choice="opt">--listen=<address></arg>
32 <arg choice="opt">--logfile=<filename></arg>
33 <arg choice="opt">--lvs</arg>
34 <arg choice="req">--nlist=<filename></arg>
35 <arg choice="opt">--no-lmaster</arg>
36 <arg choice="opt">--no-recmaster</arg>
37 <arg choice="opt">--nosetsched</arg>
38 <arg choice="req">--notification-script=<filename></arg>
39 <arg choice="opt">--public-addresses=<filename></arg>
40 <arg choice="opt">--public-interface=<interface></arg>
41 <arg choice="req">--reclock=<filename></arg>
42 <arg choice="opt">--single-public-ip=<address></arg>
43 <arg choice="opt">--socket=<filename></arg>
44 <arg choice="opt">--start-as-disabled</arg>
45 <arg choice="opt">--start-as-stopped</arg>
46 <arg choice="opt">--syslog</arg>
47 <arg choice="opt">--log-ringbuf-size=<num-entries></arg>
48 <arg choice="opt">--torture</arg>
49 <arg choice="opt">--transport=<STRING></arg>
50 <arg choice="opt">--usage</arg>
51 </cmdsynopsis>
53 </refsynopsisdiv>
55 <refsect1><title>DESCRIPTION</title>
56 <para>
57 ctdbd is the main ctdb daemon.
58 </para>
59 <para>
60 ctdbd provides a clustered version of the TDB database with automatic rebuild/recovery of the databases upon nodefailures.
61 </para>
62 <para>
63 Combined with a cluster filesystem ctdbd provides a full HA environment for services such as clustered Samba and NFS as well as other services.
64 </para>
65 <para>
66 ctdbd provides monitoring of all nodes in the cluster and automatically reconfigures the cluster and recovers upon node failures.
67 </para>
68 <para>
69 ctdbd is the main component in clustered Samba that provides a high-availability load-sharing CIFS server cluster.
70 </para>
71 </refsect1>
74 <refsect1>
75 <title>OPTIONS</title>
77 <variablelist>
78 <varlistentry><term>-? --help</term>
79 <listitem>
80 <para>
81 Print some help text to the screen.
82 </para>
83 </listitem>
84 </varlistentry>
86 <varlistentry><term>-d --debug=<DEBUGLEVEL></term>
87 <listitem>
88 <para>
89 This option sets the debuglevel on the ctdbd daemon which controls what will be written to the logfile. The default is 0 which will only log important events and errors. A larger number will provide additional logging.
90 </para>
91 </listitem>
92 </varlistentry>
94 <varlistentry><term>--dbdir=<directory></term>
95 <listitem>
96 <para>
97 This is the directory on local storage where ctdbd keeps the local
98 copy of the TDB databases. This directory is local for each node and should not be stored on the shared cluster filesystem.
99 </para>
100 <para>
101 This directory would usually be /var/ctdb .
102 </para>
103 </listitem>
104 </varlistentry>
106 <varlistentry><term>--dbdir-persistent=<directory></term>
107 <listitem>
108 <para>
109 This is the directory on local storage where ctdbd keeps the local
110 copy of the persistent TDB databases. This directory is local for each node and should not be stored on the shared cluster filesystem.
111 </para>
112 <para>
113 This directory would usually be /etc/ctdb/persistent .
114 </para>
115 </listitem>
116 </varlistentry>
118 <varlistentry><term>--event-script-dir=<directory></term>
119 <listitem>
120 <para>
121 This option is used to specify the directory where the CTDB event
122 scripts are stored.
123 </para>
124 <para>
125 This will normally be /etc/ctdb/events.d which is part of the ctdb distribution.
126 </para>
127 </listitem>
128 </varlistentry>
130 <varlistentry><term>-i --interactive</term>
131 <listitem>
132 <para>
133 By default ctdbd will detach itself from the shell and run in
134 the background as a daemon. This option makes ctdbd to start in interactive mode.
135 </para>
136 </listitem>
137 </varlistentry>
139 <varlistentry><term>--listen=<address></term>
140 <listitem>
141 <para>
142 This specifies which ip address ctdb will bind to. By default ctdbd will bind to the first address it finds in the /etc/ctdb/nodes file and which is also present on the local system in which case you do not need to provide this option.
143 </para>
144 <para>
145 This option is only required when you want to run multiple ctdbd daemons/nodes on the same physical host in which case there would be multiple entries in /etc/ctdb/nodes what would match a local interface.
146 </para>
147 </listitem>
148 </varlistentry>
150 <varlistentry><term>--logfile=<filename></term>
151 <listitem>
152 <para>
153 This is the file where ctdbd will write its log. This is usually /var/log/log.ctdb .
154 </para>
155 </listitem>
156 </varlistentry>
158 <varlistentry><term>--lvs</term>
159 <listitem>
160 <para>
161 This option is used to activate the LVS capability on a CTDB node.
162 Please see the LVS section.
163 </para>
164 </listitem>
165 </varlistentry>
167 <varlistentry><term>--nlist=<filename></term>
168 <listitem>
169 <para>
170 This file contains a list of the private ip addresses of every node in the cluster. There is one line/ip address for each node. This file must be the same for all nodes in the cluster.
171 </para>
172 <para>
173 This file is usually /etc/ctdb/nodes .
174 </para>
175 </listitem>
176 </varlistentry>
178 <varlistentry><term>--no-lmaster</term>
179 <listitem>
180 <para>
181 This argument specifies that this node can NOT become an lmaster
182 for records in the database. This means that it will never show up
183 in the vnnmap. This feature is primarily used for making a cluster
184 span across a WAN link and use CTDB as a WAN-accelerator.
185 </para>
186 <para>
187 Please see the "remote cluster nodes" section for more information.
188 </para>
189 </listitem>
190 </varlistentry>
192 <varlistentry><term>--no-recmaster</term>
193 <listitem>
194 <para>
195 This argument specifies that this node can NOT become a recmaster
196 for the database. This feature is primarily used for making a cluster
197 span across a WAN link and use CTDB as a WAN-accelerator.
198 </para>
199 <para>
200 Please see the "remote cluster nodes" section for more information.
201 </para>
202 </listitem>
203 </varlistentry>
205 <varlistentry><term>--nosetsched</term>
206 <listitem>
207 <para>
208 This is a ctdbd debugging option. this option is only used when
209 debugging ctdbd.
210 </para>
211 <para>
212 Normally ctdb will change its scheduler to run as a real-time
213 process. This is the default mode for a normal ctdbd operation
214 to gurarantee that ctdbd always gets the cpu cycles that it needs.
215 </para>
216 <para>
217 This option is used to tell ctdbd to NOT run as a real-time process
218 and instead run ctdbd as a normal userspace process.
219 This is useful for debugging and when you want to run ctdbd under
220 valgrind or gdb. (You don't want to attach valgrind or gdb to a
221 real-time process.)
222 </para>
223 </listitem>
224 </varlistentry>
226 <varlistentry><term>--notification-script=<filename></term>
227 <listitem>
228 <para>
229 This specifies a script which will be invoked by ctdb when certain
230 state changes occur in ctdbd and when you may want to trigger this
231 to run certain scripts.
232 </para>
233 <para>
234 This file is usually /etc/ctdb/notify.sh .
235 </para>
236 <para>
237 See the NOTIFICATION SCRIPT section below for more information.
238 </para>
239 </listitem>
240 </varlistentry>
242 <varlistentry><term>--public_addresses=<filename></term>
243 <listitem>
244 <para>
245 When used with IP takeover this specifies a file containing the public ip addresses to use on the cluster. This file contains a list of ip addresses netmasks and interfaces. When ctdb is operational it will distribute these public ip addresses evenly across the available nodes.
246 </para>
247 <para>
248 This is usually the file /etc/ctdb/public_addresses
249 </para>
250 </listitem>
251 </varlistentry>
253 <varlistentry><term>--public-interface=<interface></term>
254 <listitem>
255 <para>
256 This option tells ctdb which interface to attach public-addresses
257 to and also where to attach the single-public-ip when used.
258 </para>
259 <para>
260 This is only required when using public ip addresses and only when
261 you don't specify the interface explicitly in /etc/ctdb/public_addresses or when you are using --single-public-ip.
262 </para>
263 <para>
264 If you omit this argument when using public addresses or single public ip, ctdb will not be able to send out Gratious ARPs correctly or be able to kill tcp connections correctly which will lead to application failures.
265 </para>
266 </listitem>
267 </varlistentry>
269 <varlistentry><term>--reclock=<filename></term>
270 <listitem>
271 <para>
272 This is the name of the lock file stored of the shared cluster filesystem that ctdbd uses to prevent split brains from occuring.
273 This file must be stored on shared storage.
274 </para>
275 <para>
276 It is possible to run CTDB without a reclock file, but then there
277 will be no protection against split brain if the network becomes
278 partitioned. Using CTDB without a reclock file is strongly
279 discouraged.
280 </para>
281 </listitem>
282 </varlistentry>
284 <varlistentry><term>--socket=<filename></term>
285 <listitem>
286 <para>
287 This specifies the name of the domain socket that ctdbd will create. This socket is used for local clients to attach to and communicate with the ctdbd daemon.
288 </para>
289 <para>
290 The default is /tmp/ctdb.socket . You only need to use this option if you plan to run multiple ctdbd daemons on the same physical host.
291 </para>
292 </listitem>
293 </varlistentry>
295 <varlistentry><term>--start-as-disabled</term>
296 <listitem>
297 <para>
298 This makes the ctdb daemon to be DISABLED when it starts up.
299 </para>
300 <para>
301 As it is DISABLED it will not get any of the public ip addresses
302 allocated to it, and thus this allow you to start ctdb on a node
303 without causing any ip address to failover from other nodes onto
304 the new node.
305 </para>
306 <para>
307 When used, the administrator must keep track of when nodes start and
308 manually enable them again using the "ctdb enable" command, or else
309 the node will not host any services.
310 </para>
311 <para>
312 A node that is DISABLED will not host any services and will not be
313 reachable/used by any clients.
314 </para>
315 </listitem>
316 </varlistentry>
318 <varlistentry><term>--start-as-stopped</term>
319 <listitem>
320 <para>
321 This makes the ctdb daemon to be STOPPED when it starts up.
322 </para>
323 <para>
324 A node that is STOPPED does not host any public addresses. It is not part of the VNNMAP so it does act as an LMASTER. It also has all databases locked in recovery mode until restarted.
325 </para>
326 <para>
327 To restart and activate a STOPPED node, the command "ctdb continue" is used.
328 </para>
329 <para>
330 A node that is STOPPED will not host any services and will not be
331 reachable/used by any clients.
332 </para>
333 </listitem>
334 </varlistentry>
336 <varlistentry><term>--syslog</term>
337 <listitem>
338 <para>
339 Send all log messages to syslog instead of to the ctdb logfile.
340 </para>
341 </listitem>
342 </varlistentry>
344 <varlistentry><term>--log-ringbuf-size=<num-entries></term>
345 <listitem>
346 <para>
347 In addition to the normal loggign to a log file,
348 CTDBD also keeps a in-memory ringbuffer containing the most recent
349 log entries for all log levels (except DEBUG).
350 </para>
351 <para>
352 This is useful since it allows for keeping continuous logs to a file
353 at a reasonable non-verbose level, but shortly after an incident has
354 occured, a much more detailed log can be pulled from memory. This
355 can allow you to avoid having to reproduce an issue due to the
356 on-disk logs being of insufficient detail.
357 </para>
358 <para>
359 This in-memory ringbuffer contains a fixed number of the most recent
360 entries. This is settable at startup either through the
361 --log-ringbuf-size argument, or preferably by using
362 CTDB_LOG_RINGBUF_SIZE in the sysconfig file.
363 </para>
364 <para>
365 Use the "ctdb getlog" command to access this log.
366 </para>
367 </listitem>
368 </varlistentry>
371 <varlistentry><term>--torture</term>
372 <listitem>
373 <para>
374 This option is only used for development and testing of ctdbd. It adds artificial errors and failures to the common codepaths in ctdbd to verify that ctdbd can recover correctly for failures.
375 </para>
376 <para>
377 You do NOT want to use this option unless you are developing and testing new functionality in ctdbd.
378 </para>
379 </listitem>
380 </varlistentry>
382 <varlistentry><term>--transport=<STRING></term>
383 <listitem>
384 <para>
385 This option specifies which transport to use for ctdbd internode communications. The default is "tcp".
386 </para>
387 <para>
388 Currently only "tcp" is supported but "infiniband" might be
389 implemented in the future.
390 </para>
391 </listitem>
392 </varlistentry>
394 <varlistentry><term>--usage</term>
395 <listitem>
396 <para>
397 Print useage information to the screen.
398 </para>
399 </listitem>
400 </varlistentry>
402 </variablelist>
403 </refsect1>
406 <refsect1><title>Private vs Public addresses</title>
407 <para>
408 When used for ip takeover in a HA environment, each node in a ctdb
409 cluster has multiple ip addresses assigned to it. One private and one or more public.
410 </para>
412 <refsect2><title>Private address</title>
413 <para>
414 This is the physical ip address of the node which is configured in
415 linux and attached to a physical interface. This address uniquely
416 identifies a physical node in the cluster and is the ip addresses
417 that ctdbd will use to communicate with the ctdbd daemons on the
418 other nodes in the cluster.
419 </para>
420 <para>
421 The private addresses are configured in /etc/ctdb/nodes
422 (unless the --nlist option is used) and contain one line for each
423 node in the cluster. Each line contains the private ip address for one
424 node in the cluster. This file must be the same on all nodes in the
425 cluster.
426 </para>
427 <para>
428 Since the private addresses are only available to the network when the
429 corresponding node is up and running you should not use these addresses
430 for clients to connect to services provided by the cluster. Instead
431 client applications should only attach to the public addresses since
432 these are guaranteed to always be available.
433 </para>
434 <para>
435 When using ip takeover, it is strongly recommended that the private
436 addresses are configured on a private network physically separated
437 from the rest of the network and that this private network is dedicated
438 to CTDB traffic.
439 </para>
440 Example /etc/ctdb/nodes for a four node cluster:
441 <screen format="linespecific">
442 10.1.1.1
443 10.1.1.2
444 10.1.1.3
445 10.1.1.4
446 </screen>
447 </refsect2>
448 <refsect2><title>Public address</title>
449 <para>
450 A public address on the other hand is not attached to an interface.
451 This address is managed by ctdbd itself and is attached/detached to
452 a physical node at runtime.
453 </para>
454 <para>
455 The ctdb cluster will assign/reassign these public addresses across the
456 available healthy nodes in the cluster. When one node fails, its public address
457 will be migrated to and taken over by a different node in the cluster
458 to ensure that all public addresses are always available to clients as
459 long as there are still nodes available capable of hosting this address.
460 </para>
461 <para>
462 These addresses are not physically attached to a specific node.
463 The 'ctdb ip' command can be used to view the current assignment of
464 public addresses and which physical node is currently serving it.
465 </para>
466 <para>
467 On each node this file contains a list of the public addresses that
468 this node is capable of hosting.
469 The list also contain the netmask and the
470 interface where this address should be attached for the case where you
471 may want to serve data out through multiple different interfaces.
472 </para>
473 Example /etc/ctdb/public_addresses for a node that can host 4 public addresses:
474 <screen format="linespecific">
475 11.1.1.1/24 eth0
476 11.1.1.2/24 eth0
477 11.1.2.1/24 eth1
478 11.1.2.2/24 eth1
479 </screen>
481 <para>
482 In most cases this file would be the same on all nodes in a cluster but
483 there are exceptions when one may want to use different files
484 on different nodes.
485 </para>
486 Example: 4 nodes partitioned into two subgroups :
487 <screen format="linespecific">
488 Node 0:/etc/ctdb/public_addresses
489 10.1.1.1/24 eth0
490 10.1.1.2/24 eth0
492 Node 1:/etc/ctdb/public_addresses
493 10.1.1.1/24 eth0
494 10.1.1.2/24 eth0
496 Node 2:/etc/ctdb/public_addresses
497 10.2.1.1/24 eth0
498 10.2.1.2/24 eth0
500 Node 3:/etc/ctdb/public_addresses
501 10.2.1.1/24 eth0
502 10.2.1.2/24 eth0
503 </screen>
504 <para>
505 In this example nodes 0 and 1 host two public addresses on the
506 10.1.1.x network while nodes 2 and 3 host two public addresses for the
507 10.2.1.x network.
508 </para>
509 <para>
510 Ip address 10.1.1.1 can be hosted by either of nodes 0 or 1 and will be
511 available to clients as long as at least one of these two nodes are
512 available.
513 If both nodes 0 and node 1 become unavailable 10.1.1.1 also becomes
514 unavailable. 10.1.1.1 can not be failed over to node 2 or node 3 since
515 these nodes do not have this ip address listed in their public
516 addresses file.
517 </para>
518 </refsect2>
519 </refsect1>
522 <refsect1><title>Node status</title>
523 <para>
524 The current status of each node in the cluster can be viewed by the
525 'ctdb status' command.
526 </para>
527 <para>
528 There are five possible states for a node.
529 </para>
531 <para>
532 OK - This node is fully functional.
533 </para>
535 <para>
536 DISCONNECTED - This node could not be connected through the network
537 and is currently not particpating in the cluster. If there is a
538 public IP address associated with this node it should have been taken
539 over by a different node. No services are running on this node.
540 </para>
542 <para>
543 DISABLED - This node has been administratively disabled. This node is
544 still functional and participates in the CTDB cluster but its IP
545 addresses have been taken over by a different node and no services are
546 currently being hosted.
547 </para>
549 <para>
550 UNHEALTHY - A service provided by this node is malfunctioning and should
551 be investigated. The CTDB daemon itself is operational and participates
552 in the cluster. Its public IP address has been taken over by a different
553 node and no services are currently being hosted. All unhealthy nodes
554 should be investigated and require an administrative action to rectify.
555 </para>
557 <para>
558 BANNED - This node failed too many recovery attempts and has been banned
559 from participating in the cluster for a period of RecoveryBanPeriod
560 seconds. Any public IP address has been taken over by other nodes. This
561 node does not provide any services. All banned nodes should be
562 investigated and require an administrative action to rectify. This node
563 does not perticipate in the CTDB cluster but can still be communicated
564 with. I.e. ctdb commands can be sent to it.
565 </para>
567 <para>
568 STOPPED - A node that is stopped does not host any public ip addresses,
569 nor is it part of the VNNMAP. A stopped node can not become LVSMASTER,
570 RECMASTER or NATGW.
571 This node does not perticipate in the CTDB cluster but can still be
572 communicated with. I.e. ctdb commands can be sent to it.
573 </para>
574 </refsect1>
576 <refsect1>
577 <title>PUBLIC TUNABLES</title>
578 <para>
579 These are the public tuneables that can be used to control how ctdb behaves.
580 </para>
582 <refsect2><title>MaxRedirectCount</title>
583 <para>Default: 3</para>
584 <para>
585 If we are not the DMASTER and need to fetch a record across the network
586 we first send the request to the LMASTER after which the record
587 is passed onto the current DMASTER. If the DMASTER changes before
588 the request has reached that node, the request will be passed onto the
589 "next" DMASTER. For very hot records that migrate rapidly across the
590 cluster this can cause a request to "chase" the record for many hops
591 before it catches up with the record.
593 this is how many hops we allow trying to chase the DMASTER before we
594 switch back to the LMASTER again to ask for new directions.
595 </para>
596 <para>
597 When chasing a record, this is how many hops we will chase the record
598 for before going back to the LMASTER to ask for new guidance.
599 </para>
600 </refsect2>
602 <refsect2><title>SeqnumInterval</title>
603 <para>Default: 1000</para>
604 <para>
605 Some databases have seqnum tracking enabled, so that samba will be able
606 to detect asynchronously when there has been updates to the database.
607 Everytime a database is updated its sequence number is increased.
608 </para>
609 <para>
610 This tunable is used to specify in 'ms' how frequently ctdb will
611 send out updates to remote nodes to inform them that the sequence
612 number is increased.
613 </para>
614 </refsect2>
616 <refsect2><title>ControlTimeout</title>
617 <para>Default: 60</para>
618 <para>
619 This is the default
620 setting for timeout for when sending a control message to either the
621 local or a remote ctdb daemon.
622 </para>
623 </refsect2>
625 <refsect2><title>TraverseTimeout</title>
626 <para>Default: 20</para>
627 <para>
628 This setting controls how long we allow a traverse process to run.
629 After this timeout triggers, the main ctdb daemon will abort the
630 traverse if it has not yet finished.
631 </para>
632 </refsect2>
634 <refsect2><title>KeepaliveInterval</title>
635 <para>Default: 5</para>
636 <para>
637 How often in seconds should the nodes send keepalives to eachother.
638 </para>
639 </refsect2>
641 <refsect2><title>KeepaliveLimit</title>
642 <para>Default: 5</para>
643 <para>
644 After how many keepalive intervals without any traffic should a node
645 wait until marking the peer as DISCONNECTED.
646 </para>
647 <para>
648 If a node has hung, it can thus take KeepaliveInterval*(KeepaliveLimit+1)
649 seconds before we determine that the node is DISCONNECTED and that we
650 require a recovery. This limitshould not be set too high since we want
651 a hung node to be detectec, and expunged from the cluster well before
652 common CIFS timeouts (45-90 seconds) kick in.
653 </para>
654 </refsect2>
656 <refsect2><title>RecoverTimeout</title>
657 <para>Default: 20</para>
658 <para>
659 This is the default setting for timeouts for controls when sent from the
660 recovery daemon. We allow longer control timeouts from the recovery daemon
661 than from normal use since the recovery dameon often use controls that
662 can take a lot longer than normal controls.
663 </para>
664 </refsect2>
666 <refsect2><title>RecoverInterval</title>
667 <para>Default: 1</para>
668 <para>
669 How frequently in seconds should the recovery daemon perform the
670 consistency checks that determine if we need to perform a recovery or not.
671 </para>
672 </refsect2>
674 <refsect2><title>ElectionTimeout</title>
675 <para>Default: 3</para>
676 <para>
677 When electing a new recovery master, this is how many seconds we allow
678 the election to take before we either deem the election finished
679 or we fail the election and start a new one.
680 </para>
681 </refsect2>
683 <refsect2><title>TakeoverTimeout</title>
684 <para>Default: 9</para>
685 <para>
686 This is how many seconds we allow controls to take for IP failover events.
687 </para>
688 </refsect2>
690 <refsect2><title>MonitorInterval</title>
691 <para>Default: 15</para>
692 <para>
693 How often should ctdb run the event scripts to check for a nodes health.
694 </para>
695 </refsect2>
697 <refsect2><title>TickleUpdateInterval</title>
698 <para>Default: 20</para>
699 <para>
700 How often will ctdb record and store the "tickle" information used to
701 kickstart stalled tcp connections after a recovery.
702 </para>
703 </refsect2>
705 <refsect2><title>EventScriptTimeout</title>
706 <para>Default: 20</para>
707 <para>
708 How long should ctdb let an event script run before aborting it and
709 marking the node unhealthy.
710 </para>
711 </refsect2>
713 <refsect2><title>EventScriptTimeoutCount</title>
714 <para>Default: 1</para>
715 <para>
716 How many events in a row needs to timeout before we flag the node UNHEALTHY.
717 This setting is useful if your scripts can not be written so that they
718 do not hang for benign reasons.
719 </para>
720 </refsect2>
722 <refsect2><title>EventScriptUnhealthyOnTimeout</title>
723 <para>Default: 0</para>
724 <para>
725 This setting can be be used to make ctdb never become UNHEALTHY if your
726 eventscripts keep hanging/timing out.
727 </para>
728 </refsect2>
730 <refsect2><title>RecoveryGracePeriod</title>
731 <para>Default: 120</para>
732 <para>
733 During recoveries, if a node has not caused recovery failures during the
734 last grace period, any records of transgressions that the node has caused
735 recovery failures will be forgiven. This resets the ban-counter back to
736 zero for that node.
737 </para>
738 </refsect2>
740 <refsect2><title>RecoveryBanPeriod</title>
741 <para>Default: 300</para>
742 <para>
743 If a node becomes banned causing repetitive recovery failures. The node will
744 eventually become banned from the cluster.
745 This controls how long the culprit node will be banned from the cluster
746 before it is allowed to try to join the cluster again.
747 Don't set to small. A node gets banned for a reason and it is usually due
748 to real problems with the node.
749 </para>
750 </refsect2>
752 <refsect2><title>DatabaseHashSize</title>
753 <para>Default: 100001</para>
754 <para>
755 Size of the hash chains for the local store of the tdbs that ctdb manages.
756 </para>
757 </refsect2>
759 <refsect2><title>DatabaseMaxDead</title>
760 <para>Default: 5</para>
761 <para>
762 How many dead records per hashchain in the TDB database do we allow before
763 the freelist needs to be processed.
764 </para>
765 </refsect2>
767 <refsect2><title>RerecoveryTimeout</title>
768 <para>Default: 10</para>
769 <para>
770 Once a recovery has completed, no additional recoveries are permitted
771 until this timeout has expired.
772 </para>
773 </refsect2>
775 <refsect2><title>EnableBans</title>
776 <para>Default: 1</para>
777 <para>
778 When set to 0, this disables BANNING completely in the cluster and thus
779 nodes can not get banned, even it they break. Don't set to 0 unless you
780 know what you are doing. You should set this to the same value on
781 all nodes to avoid unexpected behaviour.
782 </para>
783 </refsect2>
785 <refsect2><title>DeterministicIPs</title>
786 <para>Default: 0</para>
787 <para>
788 When enabled, this tunable makes ctdb try to keep public IP addresses
789 locked to specific nodes as far as possible. This makes it easier for
790 debugging since you can know that as long as all nodes are healthy
791 public IP X will always be hosted by node Y.
792 </para>
793 <para>
794 The cost of using deterministic IP address assignment is that it
795 disables part of the logic where ctdb tries to reduce the number of
796 public IP assignment changes in the cluster. This tunable may increase
797 the number of IP failover/failbacks that are performed on the cluster
798 by a small margin.
799 </para>
801 </refsect2>
802 <refsect2><title>LCP2PublicIPs</title>
803 <para>Default: 1</para>
804 <para>
805 When enabled this switches ctdb to use the LCP2 ip allocation
806 algorithm.
807 </para>
808 </refsect2>
810 <refsect2><title>ReclockPingPeriod</title>
811 <para>Default: x</para>
812 <para>
813 Obsolete
814 </para>
815 </refsect2>
817 <refsect2><title>NoIPFailback</title>
818 <para>Default: 0</para>
819 <para>
820 When set to 1, ctdb will not perform failback of IP addresses when a node
821 becomes healthy. Ctdb WILL perform failover of public IP addresses when a
822 node becomes UNHEALTHY, but when the node becomes HEALTHY again, ctdb
823 will not fail the addresses back.
824 </para>
825 <para>
826 Use with caution! Normally when a node becomes available to the cluster
827 ctdb will try to reassign public IP addresses onto the new node as a way
828 to distribute the workload evenly across the clusternode. Ctdb tries to
829 make sure that all running nodes have approximately the same number of
830 public addresses it hosts.
831 </para>
832 <para>
833 When you enable this tunable, CTDB will no longer attempt to rebalance
834 the cluster by failing IP addresses back to the new nodes. An unbalanced
835 cluster will therefore remain unbalanced until there is manual
836 intervention from the administrator. When this parameter is set, you can
837 manually fail public IP addresses over to the new node(s) using the
838 'ctdb moveip' command.
839 </para>
840 </refsect2>
842 <refsect2><title>DisableIPFailover</title>
843 <para>Default: 0</para>
844 <para>
845 When enabled, ctdb will not perform failover or failback. Even if a
846 node fails while holding public IPs, ctdb will not recover the IPs or
847 assign them to another node.
848 </para>
849 <para>
850 When you enable this tunable, CTDB will no longer attempt to recover
851 the cluster by failing IP addresses over to other nodes. This leads to
852 a service outage until the administrator has manually performed failover
853 to replacement nodes using the 'ctdb moveip' command.
854 </para>
855 </refsect2>
857 <refsect2><title>NoIPTakeover</title>
858 <para>Default: 0</para>
859 <para>
860 When set to 1, ctdb will not allow IP addresses to be failed over
861 onto this node. Any IP addresses that the node currently hosts
862 will remain on the node but no new IP addresses can be failed over
863 to the node.
864 </para>
865 </refsect2>
867 <refsect2><title>NoIPHostOnAllDisabled</title>
868 <para>Default: 0</para>
869 <para>
870 If no nodes are healthy then by default ctdb will happily host
871 public IPs on disabled (unhealthy or administratively disabled)
872 nodes. This can cause problems, for example if the underlying
873 cluster filesystem is not mounted. When set to 1 on a node and
874 that node is disabled it, any IPs hosted by this node will be
875 released and the node will not takeover any IPs until it is no
876 longer disabled.
877 </para>
878 </refsect2>
880 <refsect2><title>DBRecordCountWarn</title>
881 <para>Default: 100000</para>
882 <para>
883 When set to non-zero, ctdb will log a warning when we try to recover a
884 database with more than this many records. This will produce a warning
885 if a database grows uncontrollably with orphaned records.
886 </para>
887 </refsect2>
889 <refsect2><title>DBRecordSizeWarn</title>
890 <para>Default: 10000000</para>
891 <para>
892 When set to non-zero, ctdb will log a warning when we try to recover a
893 database where a single record is bigger than this. This will produce
894 a warning if a database record grows uncontrollably with orphaned
895 sub-records.
896 </para>
897 </refsect2>
899 <refsect2><title>DBSizeWarn</title>
900 <para>Default: 1000000000</para>
901 <para>
902 When set to non-zero, ctdb will log a warning when we try to recover a
903 database bigger than this. This will produce
904 a warning if a database grows uncontrollably.
905 </para>
906 </refsect2>
908 <refsect2><title>VerboseMemoryNames</title>
909 <para>Default: 0</para>
910 <para>
911 This feature consumes additional memory. when used the talloc library
912 will create more verbose names for all talloc allocated objects.
913 </para>
914 </refsect2>
916 <refsect2><title>RecdPingTimeout</title>
917 <para>Default: 60</para>
918 <para>
919 If the main dameon has not heard a "ping" from the recovery dameon for
920 this many seconds, the main dameon will log a message that the recovery
921 daemon is potentially hung.
922 </para>
923 </refsect2>
925 <refsect2><title>RecdFailCount</title>
926 <para>Default: 10</para>
927 <para>
928 If the recovery daemon has failed to ping the main dameon for this many
929 consecutive intervals, the main daemon will consider the recovery daemon
930 as hung and will try to restart it to recover.
931 </para>
932 </refsect2>
934 <refsect2><title>LogLatencyMs</title>
935 <para>Default: 0</para>
936 <para>
937 When set to non-zero, this will make the main daemon log any operation that
938 took longer than this value, in 'ms', to complete.
939 These include "how long time a lockwait child process needed",
940 "how long time to write to a persistent database" but also
941 "how long did it take to get a response to a CALL from a remote node".
942 </para>
943 </refsect2>
945 <refsect2><title>RecLockLatencyMs</title>
946 <para>Default: 1000</para>
947 <para>
948 When using a reclock file for split brain prevention, if set to non-zero
949 this tunable will make the recovery dameon log a message if the fcntl()
950 call to lock/testlock the recovery file takes longer than this number of
951 ms.
952 </para>
953 </refsect2>
955 <refsect2><title>RecoveryDropAllIPs</title>
956 <para>Default: 120</para>
957 <para>
958 If we have been stuck in recovery, or stopped, or banned, mode for
959 this many seconds we will force drop all held public addresses.
960 </para>
961 </refsect2>
963 <refsect2><title>verifyRecoveryLock</title>
964 <para>Default: 1</para>
965 <para>
966 Should we take a fcntl() lock on the reclock file to verify that we are the
967 sole recovery master node on the cluster or not.
968 </para>
969 </refsect2>
971 <refsect2><title>DeferredAttachTO</title>
972 <para>Default: 120</para>
973 <para>
974 When databases are frozen we do not allow clients to attach to the
975 databases. Instead of returning an error immediately to the application
976 the attach request from the client is deferred until the database
977 becomes available again at which stage we respond to the client.
978 </para>
979 <para>
980 This timeout controls how long we will defer the request from the client
981 before timing it out and returning an error to the client.
982 </para>
983 </refsect2>
985 <refsect2><title>HopcountMakeSticky</title>
986 <para>Default: 50</para>
987 <para>
988 If the database is set to 'STICKY' mode, using the 'ctdb setdbsticky'
989 command, any record that is seen as very hot and migrating so fast that
990 hopcount surpasses 50 is set to become a STICKY record for StickyDuration
991 seconds. This means that after each migration the record will be kept on
992 the node and prevented from being migrated off the node.
993 </para>
994 <para>
995 This setting allows one to try to identify such records and stop them from
996 migrating across the cluster so fast. This will improve performance for
997 certain workloads, such as locking.tdb if many clients are opening/closing
998 the same file concurrently.
999 </para>
1000 </refsect2>
1002 <refsect2><title>StickyDuration</title>
1003 <para>Default: 600</para>
1004 <para>
1005 Once a record has been found to be fetch-lock hot and has been flagged to
1006 become STICKY, this is for how long, in seconds, the record will be
1007 flagged as a STICKY record.
1008 </para>
1009 </refsect2>
1011 <refsect2><title>StickyPindown</title>
1012 <para>Default: 200</para>
1013 <para>
1014 Once a STICKY record has been migrated onto a node, it will be pinned down
1015 on that node for this number of ms. Any request from other nodes to migrate
1016 the record off the node will be deferred until the pindown timer expires.
1017 </para>
1018 </refsect2>
1020 <refsect2><title>MaxLACount</title>
1021 <para>Default: 20</para>
1022 <para>
1023 When record content is fetched from a remote node, if it is only for
1024 reading the record, pass back the content of the record but do not yet
1025 migrate the record. Once MaxLACount identical requests from the
1026 same remote node have been seen will the record be forcefully migrated
1027 onto the requesting node. This reduces the amount of migration for a
1028 database read-mostly workload at the expense of more frequent network
1029 roundtrips.
1030 </para>
1031 </refsect2>
1033 <refsect2><title>StatHistoryInterval</title>
1034 <para>Default: 1</para>
1035 <para>
1036 Granularity of the statistics collected in the statistics history.
1037 </para>
1038 </refsect2>
1040 <refsect2><title>AllowClientDBAttach</title>
1041 <para>Default: 1</para>
1042 <para>
1043 When set to 0, clients are not allowed to attach to any databases.
1044 This can be used to temporarily block any new processes from attaching
1045 to and accessing the databases.
1046 </para>
1047 </refsect2>
1049 <refsect2><title>RecoverPDBBySeqNum</title>
1050 <para>Default: 0</para>
1051 <para>
1052 When set to non-zero, this will change how the recovery process for
1053 persistent databases ar performed. By default, when performing a database
1054 recovery, for normal as for persistent databases, recovery is
1055 record-by-record and recovery process simply collects the most recent
1056 version of every individual record.
1057 </para>
1058 <para>
1059 When set to non-zero, persistent databases will instead be recovered as
1060 a whole db and not by individual records. The node that contains the
1061 highest value stored in the record "__db_sequence_number__" is selected
1062 and the copy of that nodes database is used as the recovered database.
1063 </para>
1064 </refsect2>
1066 <refsect2><title>FetchCollapse</title>
1067 <para>Default: 1</para>
1068 <para>
1069 When many clients across many nodes try to access the same record at the
1070 same time this can lead to a fetch storm where the record becomes very
1071 active and bounces between nodes very fast. This leads to high CPU
1072 utilization of the ctdbd daemon, trying to bounce that record around
1073 very fast, and poor performance.
1074 </para>
1075 <para>
1076 This parameter is used to activate a fetch-collapse. A fetch-collapse
1077 is when we track which records we have requests in flight so that we only
1078 keep one request in flight from a certain node, even if multiple smbd
1079 processes are attemtping to fetch the record at the same time. This
1080 can improve performance and reduce CPU utilization for certain
1081 workloads.
1082 </para>
1083 <para>
1084 This timeout controls if we should collapse multiple fetch operations
1085 of the same record into a single request and defer all duplicates or not.
1086 </para>
1087 </refsect2>
1089 <refsect2><title>Samba3AvoidDeadlocks</title>
1090 <para>Default: 0</para>
1091 <para>
1092 Enable code that prevents deadlocks with Samba (only for Samba 3.x).
1093 </para>
1094 <para>
1095 This should be set to 1 when using Samba version 3.x to enable special
1096 code in CTDB to avoid deadlock with Samba version 3.x. This code
1097 is not required for Samba version 4.x and must not be enabled for
1098 Samba 4.x.
1099 </para>
1100 </refsect2>
1101 </refsect1>
1103 <refsect1><title>LVS</title>
1104 <para>
1105 LVS is a mode where CTDB presents one single IP address for the entire
1106 cluster. This is an alternative to using public IP addresses and round-robin
1107 DNS to loadbalance clients across the cluster.
1108 </para>
1110 <para>
1111 This is similar to using a layer-4 loadbalancing switch but with some restrictions.
1112 </para>
1114 <para>
1115 In this mode the cluster select a set of nodes in the cluster and loadbalance
1116 all client access to the LVS address across this set of nodes. This set of nodes are all LVS capable nodes that are HEALTHY, or if no HEALTHY nodes exists
1117 all LVS capable nodes regardless of health status.
1118 LVS will however never loadbalance traffic to nodes that are BANNED,
1119 STOPPED, DISABLED or DISCONNECTED. The "ctdb lvs" command is used to show
1120 which nodes are currently load-balanced across.
1121 </para>
1123 <para>
1124 One of the these nodes are elected as the LVSMASTER. This node receives all
1125 traffic from clients coming in to the LVS address and multiplexes it
1126 across the internal network to one of the nodes that LVS is using.
1127 When responding to the client, that node will send the data back
1128 directly to the client, bypassing the LVSMASTER node.
1129 The command "ctdb lvsmaster" will show which node is the current
1130 LVSMASTER.
1131 </para>
1133 <para>
1134 The path used for a client i/o is thus :
1135 <screen format="linespecific">
1136 (1) Client sends request packet to LVSMASTER
1137 (2) LVSMASTER passes the request on to one node across the internal network.
1138 (3) Selected node processes the request.
1139 (4) Node responds back to client.
1140 </screen>
1141 </para>
1143 <para>
1144 This means that all incoming traffic to the cluster will pass through
1145 one physical node, which limits scalability. You can send more data to the
1146 LVS address that one physical node can multiplex. This means that you
1147 should not use LVS if your I/O pattern is write-intensive since you will be
1148 limited in the available network bandwidth that node can handle.
1149 LVS does work wery well for read-intensive workloads where only smallish
1150 READ requests are going through the LVSMASTER bottleneck and the majority
1151 of the traffic volume (the data in the read replies) goes straight from
1152 the processing node back to the clients. For read-intensive i/o patterns you can acheive very high throughput rates in this mode.
1153 </para>
1155 <para>
1156 Note: you can use LVS and public addresses at the same time.
1157 </para>
1159 <refsect2><title>Configuration</title>
1160 <para>
1161 To activate LVS on a CTDB node you must specify CTDB_PUBLIC_INTERFACE and
1162 CTDB_LVS_PUBLIC_ADDRESS in /etc/sysconfig/ctdb.
1163 </para>
1165 <para>
1166 You must also specify the "--lvs" command line argument to ctdbd to activate LVS as a capability of the node. This should be done automatically for you by the /etc/init.d/ctdb script.
1167 </para>
1169 <para>
1170 Example:
1171 <screen format="linespecific">
1172 CTDB_PUBLIC_INTERFACE=eth0
1173 CTDB_LVS_PUBLIC_IP=10.0.0.237
1174 </screen>
1175 </para>
1177 </refsect2>
1179 <para>
1180 If you use LVS, you must still have a real/permanent address configured
1181 for the public interface on each node. This address must be routable
1182 and the cluster nodes must be configured so that all traffic back to client
1183 hosts are routed through this interface. This is also required in order
1184 to allow samba/winbind on the node to talk to the domain controller.
1185 (we can not use the lvs IP address to initiate outgoing traffic)
1186 </para>
1187 <para>
1188 I.e. make sure that you can "ping" both the domain controller and also
1189 all of the clients from the node BEFORE you enable LVS. Also make sure
1190 that when you ping these hosts that the traffic is routed out through the
1191 eth0 interface.
1192 </para>
1193 </refsect1>
1196 <refsect1><title>REMOTE CLUSTER NODES</title>
1197 <para>
1198 It is possible to have a CTDB cluster that spans across a WAN link.
1199 For example where you have a CTDB cluster in your datacentre but you also
1200 want to have one additional CTDB node located at a remote branch site.
1201 This is similar to how a WAN accelerator works but with the difference
1202 that while a WAN-accelerator often acts as a Proxy or a MitM, in
1203 the ctdb remote cluster node configuration the Samba instance at the remote site
1204 IS the genuine server, not a proxy and not a MitM, and thus provides 100%
1205 correct CIFS semantics to clients.
1206 </para>
1208 <para>
1209 See the cluster as one single multihomed samba server where one of
1210 the NICs (the remote node) is very far away.
1211 </para>
1213 <para>
1214 NOTE: This does require that the cluster filesystem you use can cope
1215 with WAN-link latencies. Not all cluster filesystems can handle
1216 WAN-link latencies! Whether this will provide very good WAN-accelerator
1217 performance or it will perform very poorly depends entirely
1218 on how optimized your cluster filesystem is in handling high latency
1219 for data and metadata operations.
1220 </para>
1222 <para>
1223 To activate a node as being a remote cluster node you need to set
1224 the following two parameters in /etc/sysconfig/ctdb for the remote node:
1225 <screen format="linespecific">
1226 CTDB_CAPABILITY_LMASTER=no
1227 CTDB_CAPABILITY_RECMASTER=no
1228 </screen>
1229 </para>
1231 <para>
1232 Verify with the command "ctdb getcapabilities" that that node no longer
1233 has the recmaster or the lmaster capabilities.
1234 </para>
1236 </refsect1>
1239 <refsect1><title>NAT-GW</title>
1240 <para>
1241 Sometimes it is desireable to run services on the CTDB node which will
1242 need to originate outgoing traffic to external servers. This might
1243 be contacting NIS servers, LDAP servers etc. etc.
1244 </para>
1245 <para>
1246 This can sometimes be problematic since there are situations when a
1247 node does not have any public ip addresses assigned. This could
1248 be due to the nobe just being started up and no addresses have been
1249 assigned yet or it could be that the node is UNHEALTHY in which
1250 case all public addresses have been migrated off.
1251 </para>
1252 <para>
1253 If then the service status of CTDB depends on such services being
1254 able to always being able to originate traffic to external resources
1255 this becomes extra troublesome. The node might be UNHEALTHY because
1256 the service can not be reached, and the service can not be reached
1257 because the node is UNHEALTHY.
1258 </para>
1259 <para>
1260 There are two ways to solve this problem. The first is by assigning a
1261 static ip address for one public interface on every node which will allow
1262 every node to be able to route traffic to the public network even
1263 if there are no public addresses assigned to the node.
1264 This is the simplest way but it uses up a lot of ip addresses since you
1265 have to assign both static and also public addresses to each node.
1266 </para>
1267 <refsect2><title>NAT-GW</title>
1268 <para>
1269 A second way is to use the built in NAT-GW feature in CTDB.
1270 With NAT-GW you assign one public NATGW address for each natgw group.
1271 Each NATGW group is a set of nodes in the cluster that shares the same
1272 NATGW address to talk to the outside world. Normally there would only be
1273 one NATGW group spanning the entire cluster, but in situations where one
1274 ctdb cluster spans multiple physical sites it is useful to have one
1275 NATGW group for each of the two sites.
1276 </para>
1277 <para>
1278 There can be multiple NATGW groups in one cluster but each node can only
1279 be member of one NATGW group.
1280 </para>
1281 <para>
1282 In each NATGW group, one of the nodes is designated the NAT Gateway
1283 through which all traffic that is originated by nodes in this group
1284 will be routed through if a public addresses are not available.
1285 </para>
1286 </refsect2>
1288 <refsect2><title>Configuration</title>
1289 <para>
1290 NAT-GW is configured in /etc/sysconfig/ctdb by setting the following
1291 variables:
1292 </para>
1293 <screen format="linespecific">
1294 # NAT-GW configuration
1295 # Some services running on nthe CTDB node may need to originate traffic to
1296 # remote servers before the node is assigned any IP addresses,
1297 # This is problematic since before the node has public addresses the node might
1298 # not be able to route traffic to the public networks.
1299 # One solution is to have static public addresses assigned with routing
1300 # in addition to the public address interfaces, thus guaranteeing that
1301 # a node always can route traffic to the external network.
1302 # This is the most simple solution but it uses up a large number of
1303 # additional ip addresses.
1304 #
1305 # A more complex solution is NAT-GW.
1306 # In this mode we only need one additional ip address for the cluster from
1307 # the exsternal public network.
1308 # One of the nodes in the cluster is elected to be hosting this ip address
1309 # so it can reach the external services. This node is also configured
1310 # to use NAT MASQUERADING for all traffic from the internal private network
1311 # to the external network. This node is the NAT-GW node.
1312 #
1313 # All other nodes are set up with a default rote with a metric of 10 to point
1314 # to the nat-gw node.
1315 #
1316 # The effect of this is that only when a node does not have a public address
1317 # and thus no proper routes to the external world it will instead
1318 # route all packets through the nat-gw node.
1319 #
1320 # CTDB_NATGW_NODES is the list of nodes that belong to this natgw group.
1321 # You can have multiple natgw groups in one cluster but each node
1322 # can only belong to one single natgw group.
1323 #
1324 # CTDB_NATGW_PUBLIC_IP=10.0.0.227/24
1325 # CTDB_NATGW_PUBLIC_IFACE=eth0
1326 # CTDB_NATGW_DEFAULT_GATEWAY=10.0.0.1
1327 # CTDB_NATGW_PRIVATE_NETWORK=10.1.1.0/24
1328 # CTDB_NATGW_NODES=/etc/ctdb/natgw_nodes
1329 #
1330 # Normally any node in the natgw group can act as the natgw master.
1331 # In some configurations you may have special nodes that is a part of the
1332 # cluster/natgw group, but where the node lacks connectivity to the
1333 # public network.
1334 # For these cases, set this variable to make these nodes not able to
1335 # become natgw master.
1336 #
1337 # CTDB_NATGW_SLAVE_ONLY=yes
1338 </screen>
1339 </refsect2>
1341 <refsect2><title>CTDB_NATGW_PUBLIC_IP</title>
1342 <para>
1343 This is an ip address in the public network that is used for all outgoing
1344 traffic when the public addresses are not assigned.
1345 This address will be assigned to one of the nodes in the cluster which
1346 will masquerade all traffic for the other nodes.
1347 </para>
1348 <para>
1349 Format of this parameter is IPADDRESS/NETMASK
1350 </para>
1351 </refsect2>
1353 <refsect2><title>CTDB_NATGW_PUBLIC_IFACE</title>
1354 <para>
1355 This is the physical interface where the CTDB_NATGW_PUBLIC_IP will be
1356 assigned to. This should be an interface connected to the public network.
1357 </para>
1358 <para>
1359 Format of this parameter is INTERFACE
1360 </para>
1361 </refsect2>
1363 <refsect2><title>CTDB_NATGW_DEFAULT_GATEWAY</title>
1364 <para>
1365 This is the default gateway to use on the node that is elected to host
1366 the CTDB_NATGW_PUBLIC_IP. This is the default gateway on the public network.
1367 </para>
1368 <para>
1369 Format of this parameter is IPADDRESS
1370 </para>
1371 </refsect2>
1373 <refsect2><title>CTDB_NATGW_PRIVATE_NETWORK</title>
1374 <para>
1375 This is the network/netmask used for the interal private network.
1376 </para>
1377 <para>
1378 Format of this parameter is IPADDRESS/NETMASK
1379 </para>
1380 </refsect2>
1382 <refsect2><title>CTDB_NATGW_NODES</title>
1383 <para>
1384 This is the list of all nodes that belong to the same NATGW group
1385 as this node. The default is /etc/ctdb/natgw_nodes.
1386 </para>
1387 </refsect2>
1389 <refsect2><title>Operation</title>
1390 <para>
1391 When the NAT-GW functionality is used, one of the nodes is elected
1392 to act as a NAT router for all the other nodes in the group when
1393 they need to originate traffic to the external public network.
1394 </para>
1395 <para>
1396 The NAT-GW node is assigned the CTDB_NATGW_PUBLIC_IP to the
1397 specified interface and the provided default route. Given that
1398 the NAT-GW mechanism acts as a last resort, its default route is
1399 added with a metric of 10 so that it can coexist with other
1400 configured static routes. The NAT-GW is configured to act as a
1401 router and to masquerade all traffic it receives from the
1402 internal private network and which is destined to the external
1403 network(s).
1404 </para>
1405 <para>
1406 All other nodes in the group are configured with a default route of
1407 metric 10 pointing to the designated NAT GW node.
1408 </para>
1409 <para>
1410 This is implemented in the 11.natgw eventscript. Please see the
1411 eventscript for further information.
1412 </para>
1414 </refsect2>
1416 <refsect2><title>Removing/Changing NATGW at runtime</title>
1417 <para>
1418 The following are the procedures to change/remove a NATGW configuration
1419 at runtime, without having to restart ctdbd.
1420 </para>
1422 <para>
1423 If you want to remove NATGW completely from a node, use these steps:
1424 </para>
1425 <screen format="linespecific">
1426 1, Run 'CTDB_BASE=/etc/ctdb /etc/ctdb/events.d/11.natgw removenatgw'
1427 2, Then remove the configuration from /etc/sysconfig/ctdb
1428 </screen>
1430 <para>
1431 If you want to change the NATGW configuration on a node :
1432 </para>
1433 <screen format="linespecific">
1434 1, Run 'CTDB_BASE=/etc/ctdb /etc/ctdb/events.d/11.natgw removenatgw'
1435 2, Then change the configuration in /etc/sysconfig/ctdb
1436 3, Run 'CTDB_BASE=/etc/ctdb /etc/ctdb/events.d/11.natgw updatenatgw'
1437 </screen>
1439 </refsect2>
1441 </refsect1>
1443 <refsect1>
1444 <title>POLICY ROUTING</title>
1446 <para>
1447 A node running CTDB may be a component of a complex network
1448 topology. In particular, public addresses may be spread across
1449 several different networks (or VLANs) and it may not be possible
1450 to route packets from these public addresses via the system's
1451 default route. Therefore, CTDB has support for policy routing
1452 via the 13.per_ip_routing eventscript. This allows routing to
1453 be specified for packets sourced from each public address. The
1454 routes are added and removed as CTDB moves public addresses
1455 between nodes.
1456 </para>
1458 <refsect2>
1459 <title>Configuration variables</title>
1461 <para>
1462 There are 4 configuration variables related to policy routing:
1463 </para>
1465 <variablelist>
1466 <varlistentry><term><varname>CTDB_PER_IP_ROUTING_CONF</varname></term>
1467 <listitem>
1468 <para>
1469 The name of a configuration file that specifies the
1470 desired routes for each source address. The configuration
1471 file format is discussed below. A recommended value is
1472 <filename>/etc/ctdb/policy_routing</filename>.
1473 </para>
1475 <para>
1476 The special value <constant>__auto_link_local__</constant>
1477 indicates that no configuration file is provided and that
1478 CTDB should generate reasonable link-local routes for each
1479 public address.
1480 </para>
1481 </listitem>
1482 </varlistentry>
1484 <varlistentry><term><varname>CTDB_PER_IP_ROUTING_RULE_PREF</varname></term>
1485 <listitem>
1486 <para>
1487 This sets the priority (or preference) for the routing
1488 rules that are added by CTDB.
1489 </para>
1491 <para>
1492 This should be (strictly) greater than 0 and (strictly)
1493 less than 32766. A priority of 100 is recommended, unless
1494 this conflicts with a priority already in use on the
1495 system. See ip(8) for more details.
1496 </para>
1497 </listitem>
1498 </varlistentry>
1500 <varlistentry>
1501 <term>
1502 <varname>CTDB_PER_IP_ROUTING_TABLE_ID_LOW</varname>,
1503 <varname>CTDB_PER_IP_ROUTING_TABLE_ID_HIGH</varname>
1504 </term>
1505 <listitem>
1506 <para>
1507 CTDB determines a unique routing table number to use for
1508 the routing related to each public address. These
1509 variables indicate the minimum and maximum routing table
1510 numbers that are used.
1511 </para>
1513 <para>
1514 The ip command uses some reserved routing table numbers
1515 below 255. Therefore, CTDB_PER_IP_ROUTING_TABLE_ID_LOW
1516 should be (strictly) greater than 255. 1000 and 9000
1517 are recommended values, unless this range conflicts with
1518 routing tables numbers already in use on the system.
1519 </para>
1521 <para>
1522 CTDB uses the standard file
1523 <filename>/etc/iproute2/rt_tables</filename> to maintain
1524 a mapping between the routing table numbers and labels.
1525 The label for a public address <addr;gt; will look
1526 like ctdb.<addr>. This means that the associated
1527 rules and routes are easy to read (and manipulate).
1528 </para>
1529 </listitem>
1530 </varlistentry>
1531 </variablelist>
1532 </refsect2>
1534 <refsect2>
1535 <title>Configuration file</title>
1537 <para>
1538 The format of each line is:
1539 </para>
1541 <screen>
1542 <public_address> <network> [ <gateway> ]
1543 </screen>
1545 <para>
1546 Leading whitespace is ignored and arbitrary whitespace may be
1547 used as a separator. Lines that have a "public address" item
1548 that doesn't match an actual public address are ignored. This
1549 means that comment lines can be added using a leading
1550 character such as '#', since this will never match an IP
1551 address.
1552 </para>
1554 <para>
1555 A line without a gateway indicates a link local route.
1556 </para>
1558 <para>
1559 For example, consider the configuration line:
1560 </para>
1562 <screen>
1563 192.168.1.99 192.168.1.1/24
1564 </screen>
1566 <para>
1567 If the corresponding public_addresses line is:
1568 </para>
1570 <screen>
1571 192.168.1.99/24 eth2,eth3
1572 </screen>
1574 <para>
1575 <varname>CTDB_PER_IP_ROUTING_RULE_PREF</varname> is 100, and
1576 CTDB adds the address to eth2 then the following routing
1577 information is added:
1578 </para>
1580 <screen>
1581 ip rule add from 192.168.1.99 pref 100 table ctdb.192.168.1.99
1582 ip route add 192.168.1.0/24 dev eth2 table ctdb.192.168.1.99
1583 </screen>
1585 <para>
1586 This causes traffic from 192.168.1.1 to 192.168.1.0/24 go via
1587 eth2.
1588 </para>
1590 <para>
1591 The <command>ip rule</command> command will show (something
1592 like - depending on other public addresses and other routes on
1593 the system):
1594 </para>
1596 <screen>
1597 0: from all lookup local
1598 100: from 192.168.1.99 lookup ctdb.192.168.1.99
1599 32766: from all lookup main
1600 32767: from all lookup default
1601 </screen>
1603 <para>
1604 <command>ip route show table ctdb.192.168.1.99</command> will show:
1605 </para>
1607 <screen>
1608 192.168.1.0/24 dev eth2 scope link
1609 </screen>
1611 <para>
1612 The usual use for a line containing a gateway is to add a
1613 default route corresponding to a particular source address.
1614 Consider this line of configuration:
1615 </para>
1617 <screen>
1618 192.168.1.99 0.0.0.0/0 192.168.1.1
1619 </screen>
1621 <para>
1622 In the situation described above this will cause an extra
1623 routing command to be executed:
1624 </para>
1626 <screen>
1627 ip route add 0.0.0.0/0 via 192.168.1.1 dev eth2 table ctdb.192.168.1.99
1628 </screen>
1630 <para>
1631 With both configuration lines, <command>ip route show table
1632 ctdb.192.168.1.99</command> will show:
1633 </para>
1635 <screen>
1636 192.168.1.0/24 dev eth2 scope link
1637 default via 192.168.1.1 dev eth2
1638 </screen>
1639 </refsect2>
1641 <refsect2>
1642 <title>Example configuration</title>
1644 <para>
1645 Here is a more complete example configuration.
1646 </para>
1648 <screen>
1649 /etc/ctdb/public_addresses:
1651 192.168.1.98 eth2,eth3
1652 192.168.1.99 eth2,eth3
1654 /etc/ctdb/policy_routing:
1656 192.168.1.98 192.168.1.0/24
1657 192.168.1.98 192.168.200.0/24 192.168.1.254
1658 192.168.1.98 0.0.0.0/0 192.168.1.1
1659 192.168.1.99 192.168.1.0/24
1660 192.168.1.99 192.168.200.0/24 192.168.1.254
1661 192.168.1.99 0.0.0.0/0 192.168.1.1
1662 </screen>
1664 <para>
1665 The routes local packets as expected, the default route is as
1666 previously discussed, but packets to 192.168.200.0/24 are
1667 routed via the alternate gateway 192.168.1.254.
1668 </para>
1670 </refsect2>
1671 </refsect1>
1673 <refsect1><title>NOTIFICATION SCRIPT</title>
1674 <para>
1675 Notification scripts are used with ctdb to have a call-out from ctdb
1676 to a user-specified script when certain state changes occur in ctdb.
1677 This is commonly to set up either sending SNMP traps or emails
1678 when a node becomes unhealthy and similar.
1679 </para>
1680 <para>
1681 This is activated by setting CTDB_NOTIFY_SCRIPT=<your script> in the
1682 sysconfig file, or by adding --notification-script=<your script>.
1683 </para>
1684 <para>
1685 See /etc/ctdb/notify.sh for an example script. This script
1686 executes files in <filename>/etc/ctdb/notify.d/</filename>, so
1687 it is recommended that you handle notifications using the
1688 example script and by place executable scripts in
1689 <filename>/etc/ctdb/notify.d/</filename> to handle the desired
1690 notifications.
1691 </para>
1692 <para>
1693 CTDB currently generates notifications on these state changes:
1694 </para>
1696 <refsect2><title>unhealthy</title>
1697 <para>
1698 This call-out is triggered when the node changes to UNHEALTHY state.
1699 </para>
1700 </refsect2>
1702 <refsect2><title>healthy</title>
1703 <para>
1704 This call-out is triggered when the node changes to HEALTHY state.
1705 </para>
1706 </refsect2>
1708 <refsect2><title>startup</title>
1709 <para>
1710 This call-out is triggered when ctdb has started up and all managed services are up and running.
1711 </para>
1712 </refsect2>
1714 </refsect1>
1717 <refsect1><title>ClamAV Daemon</title>
1718 <para>
1719 CTDB has support to manage the popular anti-virus daemon ClamAV.
1720 This support is implemented through the
1721 eventscript : /etc/ctdb/events.d/31.clamd.
1722 </para>
1724 <refsect2><title>Configuration</title>
1725 <para>
1726 Start by configuring CLAMAV normally and test that it works. Once this is
1727 done, copy the configuration files over to all the nodes so that all nodes
1728 share identical CLAMAV configurations.
1729 Once this is done you can proceed with the intructions below to activate
1730 CTDB support for CLAMAV.
1731 </para>
1733 <para>
1734 First, to activate CLAMAV support in CTDB, edit /etc/sysconfig/ctdb and add the two lines :
1735 </para>
1736 <screen format="linespecific">
1737 CTDB_MANAGES_CLAMD=yes
1738 CTDB_CLAMD_SOCKET="/path/to/clamd.socket"
1739 </screen>
1741 <para>
1742 Second, activate the eventscript
1743 </para>
1744 <screen format="linespecific">
1745 ctdb enablescript 31.clamd
1746 </screen>
1748 <para>
1749 Third, CTDB will now be starting and stopping this service accordingly,
1750 so make sure that the system is not configured to start/stop this service
1751 automatically.
1752 On RedHat systems you can disable the system starting/stopping CLAMAV automatically by running :
1753 <screen format="linespecific">
1754 chkconfig clamd off
1755 </screen>
1756 </para>
1759 <para>
1760 Once you have restarted CTDBD, use
1761 <screen format="linespecific">
1762 ctdb scriptstatus
1763 </screen>
1764 and verify that the 31.clamd eventscript is listed and that it was executed successfully.
1765 </para>
1767 </refsect2>
1768 </refsect1>
1773 <refsect1><title>SEE ALSO</title>
1774 <para>
1775 ctdb(1), onnode(1)
1776 <ulink url="http://ctdb.samba.org/"/>
1777 </para>
1778 </refsect1>
1780 <refsect1><title>COPYRIGHT/LICENSE</title>
1781 <literallayout>
1782 Copyright (C) Andrew Tridgell 2007
1783 Copyright (C) Ronnie sahlberg 2007
1785 This program is free software; you can redistribute it and/or modify
1786 it under the terms of the GNU General Public License as published by
1787 the Free Software Foundation; either version 3 of the License, or (at
1788 your option) any later version.
1790 This program is distributed in the hope that it will be useful, but
1791 WITHOUT ANY WARRANTY; without even the implied warranty of
1792 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
1793 General Public License for more details.
1795 You should have received a copy of the GNU General Public License
1796 along with this program; if not, see http://www.gnu.org/licenses/.
1797 </literallayout>
1798 </refsect1>
1799 </refentry>