1 <html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>ctdbd</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="refentry" title="ctdbd"><a name="ctdbd.1"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>ctdbd — The CTDB cluster daemon</p></div><div class="refsynopsisdiv" title="Synopsis"><h2>Synopsis</h2><div class="cmdsynopsis"><p><code class="command">ctdbd</code> </p></div><div class="cmdsynopsis"><p><code class="command">ctdbd</code> [-? --help] [-d --debug=<INTEGER>] {--dbdir=<directory>} {--dbdir-persistent=<directory>} [--event-script-dir=<directory>] [-i --interactive] [--listen=<address>] [--logfile=<filename>] [--lvs] {--nlist=<filename>} [--no-lmaster] [--no-recmaster] [--nosetsched] {--notification-script=<filename>} [--public-addresses=<filename>] [--public-interface=<interface>] {--reclock=<filename>} [--single-public-ip=<address>] [--socket=<filename>] [--start-as-disabled] [--start-as-stopped] [--syslog] [--log-ringbuf-size=<num-entries>] [--torture] [--transport=<STRING>] [--usage]</p></div></div><div class="refsect1" title="DESCRIPTION"><a name="id424915"></a><h2>DESCRIPTION</h2><p>
2 ctdbd is the main ctdb daemon.
4 ctdbd provides a clustered version of the TDB database with automatic rebuild/recovery of the databases upon nodefailures.
6 Combined with a cluster filesystem ctdbd provides a full HA environment for services such as clustered Samba and NFS as well as other services.
8 ctdbd provides monitoring of all nodes in the cluster and automatically reconfigures the cluster and recovers upon node failures.
10 ctdbd is the main component in clustered Samba that provides a high-availability load-sharing CIFS server cluster.
11 </p></div><div class="refsect1" title="OPTIONS"><a name="id424942"></a><h2>OPTIONS</h2><div class="variablelist"><dl><dt><span class="term">-? --help</span></dt><dd><p>
12 Print some help text to the screen.
13 </p></dd><dt><span class="term">-d --debug=<DEBUGLEVEL></span></dt><dd><p>
14 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.
15 </p></dd><dt><span class="term">--dbdir=<directory></span></dt><dd><p>
16 This is the directory on local storage where ctdbd keeps the local
17 copy of the TDB databases. This directory is local for each node and should not be stored on the shared cluster filesystem.
19 This directory would usually be /var/ctdb .
20 </p></dd><dt><span class="term">--dbdir-persistent=<directory></span></dt><dd><p>
21 This is the directory on local storage where ctdbd keeps the local
22 copy of the persistent TDB databases. This directory is local for each node and should not be stored on the shared cluster filesystem.
24 This directory would usually be /etc/ctdb/persistent .
25 </p></dd><dt><span class="term">--event-script-dir=<directory></span></dt><dd><p>
26 This option is used to specify the directory where the CTDB event
29 This will normally be /etc/ctdb/events.d which is part of the ctdb distribution.
30 </p></dd><dt><span class="term">-i --interactive</span></dt><dd><p>
31 By default ctdbd will detach itself from the shell and run in
32 the background as a daemon. This option makes ctdbd to start in interactive mode.
33 </p></dd><dt><span class="term">--listen=<address></span></dt><dd><p>
34 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.
36 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.
37 </p></dd><dt><span class="term">--logfile=<filename></span></dt><dd><p>
38 This is the file where ctdbd will write its log. This is usually /var/log/log.ctdb .
39 </p></dd><dt><span class="term">--lvs</span></dt><dd><p>
40 This option is used to activate the LVS capability on a CTDB node.
41 Please see the LVS section.
42 </p></dd><dt><span class="term">--nlist=<filename></span></dt><dd><p>
43 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.
45 This file is usually /etc/ctdb/nodes .
46 </p></dd><dt><span class="term">--no-lmaster</span></dt><dd><p>
47 This argument specifies that this node can NOT become an lmaster
48 for records in the database. This means that it will never show up
49 in the vnnmap. This feature is primarily used for making a cluster
50 span across a WAN link and use CTDB as a WAN-accelerator.
52 Please see the "remote cluster nodes" section for more information.
53 </p></dd><dt><span class="term">--no-recmaster</span></dt><dd><p>
54 This argument specifies that this node can NOT become a recmaster
55 for the database. This feature is primarily used for making a cluster
56 span across a WAN link and use CTDB as a WAN-accelerator.
58 Please see the "remote cluster nodes" section for more information.
59 </p></dd><dt><span class="term">--nosetsched</span></dt><dd><p>
60 This is a ctdbd debugging option. this option is only used when
63 Normally ctdb will change its scheduler to run as a real-time
64 process. This is the default mode for a normal ctdbd operation
65 to gurarantee that ctdbd always gets the cpu cycles that it needs.
67 This option is used to tell ctdbd to NOT run as a real-time process
68 and instead run ctdbd as a normal userspace process.
69 This is useful for debugging and when you want to run ctdbd under
70 valgrind or gdb. (You don't want to attach valgrind or gdb to a
72 </p></dd><dt><span class="term">--notification-script=<filename></span></dt><dd><p>
73 This specifies a script which will be invoked by ctdb when certain
74 state changes occur in ctdbd and when you may want to trigger this
75 to run certain scripts.
77 This file is usually /etc/ctdb/notify.sh .
79 See the NOTIFICATION SCRIPT section below for more information.
80 </p></dd><dt><span class="term">--public_addresses=<filename></span></dt><dd><p>
81 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.
83 This is usually the file /etc/ctdb/public_addresses
84 </p></dd><dt><span class="term">--public-interface=<interface></span></dt><dd><p>
85 This option tells ctdb which interface to attach public-addresses
86 to and also where to attach the single-public-ip when used.
88 This is only required when using public ip addresses and only when
89 you don't specify the interface explicitly in /etc/ctdb/public_addresses or when you are using --single-public-ip.
91 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.
92 </p></dd><dt><span class="term">--reclock=<filename></span></dt><dd><p>
93 This is the name of the lock file stored of the shared cluster filesystem that ctdbd uses to prevent split brains from occuring.
94 This file must be stored on shared storage.
96 It is possible to run CTDB without a reclock file, but then there
97 will be no protection against split brain if the network becomes
98 partitioned. Using CTDB without a reclock file is strongly
100 </p></dd><dt><span class="term">--socket=<filename></span></dt><dd><p>
101 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.
103 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.
104 </p></dd><dt><span class="term">--start-as-disabled</span></dt><dd><p>
105 This makes the ctdb daemon to be DISABLED when it starts up.
107 As it is DISABLED it will not get any of the public ip addresses
108 allocated to it, and thus this allow you to start ctdb on a node
109 without causing any ip address to failover from other nodes onto
112 When used, the administrator must keep track of when nodes start and
113 manually enable them again using the "ctdb enable" command, or else
114 the node will not host any services.
116 A node that is DISABLED will not host any services and will not be
117 reachable/used by any clients.
118 </p></dd><dt><span class="term">--start-as-stopped</span></dt><dd><p>
119 This makes the ctdb daemon to be STOPPED when it starts up.
121 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.
123 To restart and activate a STOPPED node, the command "ctdb continue" is used.
125 A node that is STOPPED will not host any services and will not be
126 reachable/used by any clients.
127 </p></dd><dt><span class="term">--syslog</span></dt><dd><p>
128 Send all log messages to syslog instead of to the ctdb logfile.
129 </p></dd><dt><span class="term">--log-ringbuf-size=<num-entries></span></dt><dd><p>
130 In addition to the normal loggign to a log file,
131 CTDBD also keeps a in-memory ringbuffer containing the most recent
132 log entries for all log levels (except DEBUG).
134 This is useful since it allows for keeping continous logs to a file
135 at a reasonable non-verbose level, but shortly after an incident has
136 occured, a much more detailed log can be pulled from memory. This
137 can allow you to avoid having to reproduce an issue due to the
138 on-disk logs being of insufficient detail.
140 This in-memory ringbuffer contains a fixed number of the most recent
141 entries. This is settable at startup either through the
142 --log-ringbuf-size argument, or preferably by using
143 CTDB_LOG_RINGBUF_SIZE in the sysconfig file.
145 Use the "ctdb getlog" command to access this log.
146 </p></dd><dt><span class="term">--torture</span></dt><dd><p>
147 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.
149 You do NOT want to use this option unless you are developing and testing new functionality in ctdbd.
150 </p></dd><dt><span class="term">--transport=<STRING></span></dt><dd><p>
151 This option specifies which transport to use for ctdbd internode communications. The default is "tcp".
153 Currently only "tcp" is supported but "infiniband" might be
154 implemented in the future.
155 </p></dd><dt><span class="term">--usage</span></dt><dd><p>
156 Print useage information to the screen.
157 </p></dd></dl></div></div><div class="refsect1" title="Private vs Public addresses"><a name="id382958"></a><h2>Private vs Public addresses</h2><p>
158 When used for ip takeover in a HA environment, each node in a ctdb
159 cluster has multiple ip addresses assigned to it. One private and one or more public.
160 </p><div class="refsect2" title="Private address"><a name="id382967"></a><h3>Private address</h3><p>
161 This is the physical ip address of the node which is configured in
162 linux and attached to a physical interface. This address uniquely
163 identifies a physical node in the cluster and is the ip addresses
164 that ctdbd will use to communicate with the ctdbd daemons on the
165 other nodes in the cluster.
167 The private addresses are configured in /etc/ctdb/nodes
168 (unless the --nlist option is used) and contain one line for each
169 node in the cluster. Each line contains the private ip address for one
170 node in the cluster. This file must be the same on all nodes in the
173 Since the private addresses are only available to the network when the
174 corresponding node is up and running you should not use these addresses
175 for clients to connect to services provided by the cluster. Instead
176 client applications should only attach to the public addresses since
177 these are guaranteed to always be available.
179 When using ip takeover, it is strongly recommended that the private
180 addresses are configured on a private network physically separated
181 from the rest of the network and that this private network is dedicated
184 Example /etc/ctdb/nodes for a four node cluster:
190 </pre></div><div class="refsect2" title="Public address"><a name="id383002"></a><h3>Public address</h3><p>
191 A public address on the other hand is not attached to an interface.
192 This address is managed by ctdbd itself and is attached/detached to
193 a physical node at runtime.
195 The ctdb cluster will assign/reassign these public addresses across the
196 available healthy nodes in the cluster. When one node fails, its public address
197 will be migrated to and taken over by a different node in the cluster
198 to ensure that all public addresses are always available to clients as
199 long as there are still nodes available capable of hosting this address.
201 These addresses are not physically attached to a specific node.
202 The 'ctdb ip' command can be used to view the current assignment of
203 public addresses and which physical node is currently serving it.
205 On each node this file contains a list of the public addresses that
206 this node is capable of hosting.
207 The list also contain the netmask and the
208 interface where this address should be attached for the case where you
209 may want to serve data out through multiple different interfaces.
211 Example /etc/ctdb/public_addresses for a node that can host 4 public addresses:
218 In most cases this file would be the same on all nodes in a cluster but
219 there are exceptions when one may want to use different files
222 Example: 4 nodes partitioned into two subgroups :
224 Node 0:/etc/ctdb/public_addresses
228 Node 1:/etc/ctdb/public_addresses
232 Node 2:/etc/ctdb/public_addresses
236 Node 3:/etc/ctdb/public_addresses
240 In this example nodes 0 and 1 host two public addresses on the
241 10.1.1.x network while nodes 2 and 3 host two public addresses for the
244 Ip address 10.1.1.1 can be hosted by either of nodes 0 or 1 and will be
245 available to clients as long as at least one of these two nodes are
247 If both nodes 0 and node 1 become unavailable 10.1.1.1 also becomes
248 unavailable. 10.1.1.1 can not be failed over to node 2 or node 3 since
249 these nodes do not have this ip address listed in their public
251 </p></div></div><div class="refsect1" title="Node status"><a name="id383063"></a><h2>Node status</h2><p>
252 The current status of each node in the cluster can be viewed by the
253 'ctdb status' command.
255 There are five possible states for a node.
257 OK - This node is fully functional.
259 DISCONNECTED - This node could not be connected through the network
260 and is currently not particpating in the cluster. If there is a
261 public IP address associated with this node it should have been taken
262 over by a different node. No services are running on this node.
264 DISABLED - This node has been administratively disabled. This node is
265 still functional and participates in the CTDB cluster but its IP
266 addresses have been taken over by a different node and no services are
267 currently being hosted.
269 UNHEALTHY - A service provided by this node is malfunctioning and should
270 be investigated. The CTDB daemon itself is operational and participates
271 in the cluster. Its public IP address has been taken over by a different
272 node and no services are currently being hosted. All unhealthy nodes
273 should be investigated and require an administrative action to rectify.
275 BANNED - This node failed too many recovery attempts and has been banned
276 from participating in the cluster for a period of RecoveryBanPeriod
277 seconds. Any public IP address has been taken over by other nodes. This
278 node does not provide any services. All banned nodes should be
279 investigated and require an administrative action to rectify. This node
280 does not perticipate in the CTDB cluster but can still be communicated
281 with. I.e. ctdb commands can be sent to it.
283 STOPPED - A node that is stopped does not host any public ip addresses,
284 nor is it part of the VNNMAP. A stopped node can not become LVSMASTER,
286 This node does not perticipate in the CTDB cluster but can still be
287 communicated with. I.e. ctdb commands can be sent to it.
288 </p></div><div class="refsect1" title="PUBLIC TUNABLES"><a name="id383111"></a><h2>PUBLIC TUNABLES</h2><p>
289 These are the public tuneables that can be used to control how ctdb behaves.
290 </p><div class="refsect2" title="KeepaliveInterval"><a name="id383121"></a><h3>KeepaliveInterval</h3><p>Default: 1</p><p>
291 How often should the nodes send keepalives to eachother.
292 </p></div><div class="refsect2" title="KeepaliveLimit"><a name="id383133"></a><h3>KeepaliveLimit</h3><p>Default: 5</p><p>
293 After how many keepalive intervals without any traffic should a node
294 wait until marking the peer as DISCONNECTED.
295 </p></div><div class="refsect2" title="MonitorInterval"><a name="id383147"></a><h3>MonitorInterval</h3><p>Default: 15</p><p>
296 How often should ctdb run the event scripts to check for a nodes health.
297 </p></div><div class="refsect2" title="TickleUpdateInterval"><a name="id383160"></a><h3>TickleUpdateInterval</h3><p>Default: 20</p><p>
298 How often will ctdb record and store the "tickle" information used to
299 kickstart stalled tcp connections after a recovery.
300 </p></div><div class="refsect2" title="EventScriptTimeout"><a name="id383173"></a><h3>EventScriptTimeout</h3><p>Default: 20</p><p>
301 How long should ctdb let an event script run before aborting it and
302 marking the node unhealthy.
303 </p></div><div class="refsect2" title="RecoveryBanPeriod"><a name="id383186"></a><h3>RecoveryBanPeriod</h3><p>Default: 300</p><p>
304 If a node becomes banned causing repetitive recovery failures. The node will
305 eventually become banned from the cluster.
306 This controls how long the culprit node will be banned from the cluster
307 before it is allowed to try to join the cluster again.
308 Don't set to small. A node gets banned for a reason and it is usually due
309 to real problems with the node.
310 </p></div><div class="refsect2" title="DatabaseHashSize"><a name="id383202"></a><h3>DatabaseHashSize</h3><p>Default: 100000</p><p>
311 Size of the hash chains for the local store of the tdbs that ctdb manages.
312 </p></div><div class="refsect2" title="RerecoveryTimeout"><a name="id383215"></a><h3>RerecoveryTimeout</h3><p>Default: 10</p><p>
313 Once a recovery has completed, no additional recoveries are permitted until this timeout has expired.
314 </p></div><div class="refsect2" title="EnableBans"><a name="id383228"></a><h3>EnableBans</h3><p>Default: 1</p><p>
315 When set to 0, this disables BANNING completely in the cluster and thus nodes can not get banned, even it they break. Don't set to 0.
316 </p></div><div class="refsect2" title="DeterministicIPs"><a name="id383242"></a><h3>DeterministicIPs</h3><p>Default: 1</p><p>
317 When enabled, this tunable makes ctdb try to keep public IP addresses locked to specific nodes as far as possible. This makes it easier for debugging since you can know that as long as all nodes are healthy public IP X will always be hosted by node Y.
319 The cost of using deterministic IP address assignment is that it disables part of the logic where ctdb tries to reduce the number of public IP assignment changes in the cluster. This tunable may increase the number of IP failover/failbacks that are performed on the cluster by a small margin.
320 </p></div><div class="refsect2" title="DisableWhenUnhealthy"><a name="id383262"></a><h3>DisableWhenUnhealthy</h3><p>Default: 0</p><p>
321 When set, As soon as a node becomes unhealthy, that node will also automatically become permanently DISABLED. Once a node is DISABLED, the only way to make it participate in the cluster again and host services is by manually enabling the node again using 'ctdb enable'.
323 This disables parts of the resilience and robustness of the cluster and should ONLY be used when the system administrator is actively monitoring the cluster, so that nodes can be enabled again.
324 </p></div><div class="refsect2" title="NoIPFailback"><a name="id383282"></a><h3>NoIPFailback</h3><p>Default: 0</p><p>
325 When set to 1, ctdb will not perform failback of IP addresses when a node becomes healthy. Ctdb WILL perform failover of public IP addresses when a node becomes UNHEALTHY, but when the node becomes HEALTHY again, ctdb will not fail the addresses back.
327 Use with caution! Normally when a node becomes available to the cluster
328 ctdb will try to reassign public IP addresses onto the new node as a way to distribute the workload evenly across the clusternode. Ctdb tries to make sure that all running nodes have approximately the same number of public addresses it hosts.
330 When you enable this tunable, CTDB will no longer attempt to rebalance the cluster by failing IP addresses back to the new nodes. An unbalanced cluster will therefore remain unbalanced until there is manual intervention from the administrator. When this parameter is set, you can manually fail public IP addresses over to the new node(s) using the 'ctdb moveip' command.
331 </p></div></div><div class="refsect1" title="LVS"><a name="id383310"></a><h2>LVS</h2><p>
332 LVS is a mode where CTDB presents one single IP address for the entire
333 cluster. This is an alternative to using public IP addresses and round-robin
334 DNS to loadbalance clients across the cluster.
336 This is similar to using a layer-4 loadbalancing switch but with some restrictions.
338 In this mode the cluster select a set of nodes in the cluster and loadbalance
339 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
340 all LVS capable nodes regardless of health status.
341 LVS will however never loadbalance traffic to nodes that are BANNED,
342 STOPPED, DISABLED or DISCONNECTED. The "ctdb lvs" command is used to show
343 which nodes are currently load-balanced across.
345 One of the these nodes are elected as the LVSMASTER. This node receives all
346 traffic from clients coming in to the LVS address and multiplexes it
347 across the internal network to one of the nodes that LVS is using.
348 When responding to the client, that node will send the data back
349 directly to the client, bypassing the LVSMASTER node.
350 The command "ctdb lvsmaster" will show which node is the current
353 The path used for a client i/o is thus :
354 </p><pre class="screen">
355 (1) Client sends request packet to LVSMASTER
356 (2) LVSMASTER passes the request on to one node across the internal network.
357 (3) Selected node processes the request.
358 (4) Node responds back to client.
361 This means that all incoming traffic to the cluster will pass through
362 one physical node, which limits scalability. You can send more data to the
363 LVS address that one physical node can multiplex. This means that you
364 should not use LVS if your I/O pattern is write-intensive since you will be
365 limited in the available network bandwidth that node can handle.
366 LVS does work wery well for read-intensive workloads where only smallish
367 READ requests are going through the LVSMASTER bottleneck and the majority
368 of the traffic volume (the data in the read replies) goes straight from
369 the processing node back to the clients. For read-intensive i/o patterns you can acheive very high throughput rates in this mode.
371 Note: you can use LVS and public addresses at the same time.
372 </p><div class="refsect2" title="Configuration"><a name="id383366"></a><h3>Configuration</h3><p>
373 To activate LVS on a CTDB node you must specify CTDB_PUBLIC_INTERFACE and
374 CTDB_LVS_PUBLIC_ADDRESS in /etc/sysconfig/ctdb.
376 You must also specify the "--lvs" command line argument to ctdbd to activete LVS as a capability of the node. This should be done automatically for you by the /etc/init.d/ctdb script.
379 </p><pre class="screen">
380 CTDB_PUBLIC_INTERFACE=eth0
381 CTDB_LVS_PUBLIC_IP=10.0.0.237
384 If you use LVS, you must still have a real/permanent address configured
385 for the public interface on each node. This address must be routable
386 and the cluster nodes must be configured so that all traffic back to client
387 hosts are routed through this interface. This is also required in order
388 to allow samba/winbind on the node to talk to the domain controller.
389 (we can not use the lvs IP address to initiate outgoing traffic)
391 I.e. make sure that you can "ping" both the domain controller and also
392 all of the clients from the node BEFORE you enable LVS. Also make sure
393 that when you ping these hosts that the traffic is routed out through the
395 </p></div><div class="refsect1" title="REMOTE CLUSTER NODES"><a name="id383403"></a><h2>REMOTE CLUSTER NODES</h2><p>
396 It is possible to have a CTDB cluster that spans across a WAN link.
397 For example where you have a CTDB cluster in your datacentre but you also
398 want to have one additional CTDB node located at a remote branch site.
399 This is similar to how a WAN accelerator works but with the difference
400 that while a WAN-accelerator often acts as a Proxy or a MitM, in
401 the ctdb remote cluster node configuration the Samba instance at the remote site
402 IS the genuine server, not a proxy and not a MitM, and thus provides 100%
403 correct CIFS semantics to clients.
405 See the cluster as one single multihomed samba server where one of
406 the NICs (the remote node) is very far away.
408 NOTE: This does require that the cluster filesystem you use can cope
409 with WAN-link latencies. Not all cluster filesystems can handle
410 WAN-link latencies! Whether this will provide very good WAN-accelerator
411 performance or it will perform very poorly depends entirely
412 on how optimized your cluster filesystem is in handling high latency
413 for data and metadata operations.
415 To activate a node as being a remote cluster node you need to set
416 the following two parameters in /etc/sysconfig/ctdb for the remote node:
417 </p><pre class="screen">
418 CTDB_CAPABILITY_LMASTER=no
419 CTDB_CAPABILITY_RECMASTER=no
422 Verify with the command "ctdb getcapabilities" that that node no longer
423 has the recmaster or the lmaster capabilities.
424 </p></div><div class="refsect1" title="NAT-GW"><a name="id383442"></a><h2>NAT-GW</h2><p>
425 Sometimes it is desireable to run services on the CTDB node which will
426 need to originate outgoing traffic to external servers. This might
427 be contacting NIS servers, LDAP servers etc. etc.
429 This can sometimes be problematic since there are situations when a
430 node does not have any public ip addresses assigned. This could
431 be due to the nobe just being started up and no addresses have been
432 assigned yet or it could be that the node is UNHEALTHY in which
433 case all public addresses have been migrated off.
435 If then the service status of CTDB depends on such services being
436 able to always being able to originate traffic to external resources
437 this becomes extra troublesome. The node might be UNHEALTHY because
438 the service can not be reached, and the service can not be reached
439 because the node is UNHEALTHY.
441 There are two ways to solve this problem. The first is by assigning a
442 static ip address for one public interface on every node which will allow
443 every node to be able to route traffic to the public network even
444 if there are no public addresses assigned to the node.
445 This is the simplest way but it uses up a lot of ip addresses since you
446 have to assign both static and also public addresses to each node.
447 </p><div class="refsect2" title="NAT-GW"><a name="id426195"></a><h3>NAT-GW</h3><p>
448 A second way is to use the built in NAT-GW feature in CTDB.
449 With NAT-GW you assign one public NATGW address for each natgw group.
450 Each NATGW group is a set of nodes in the cluster that shares the same
451 NATGW address to talk to the outside world. Normally there would only be
452 one NATGW group spanning the entire cluster, but in situations where one
453 ctdb cluster spans multiple physical sites it is useful to have one
454 NATGW group for each of the two sites.
456 There can be multiple NATGW groups in one cluster but each node can only
457 be member of one NATGW group.
459 In each NATGW group, one of the nodes is designated the NAT Gateway
460 through which all traffic that is originated by nodes in this group
461 will be routed through if a public addresses are not available.
462 </p></div><div class="refsect2" title="Configuration"><a name="id426217"></a><h3>Configuration</h3><p>
463 NAT-GW is configured in /etc/sysconfigctdb by setting the following
465 </p><pre class="screen">
466 # NAT-GW configuration
467 # Some services running on nthe CTDB node may need to originate traffic to
468 # remote servers before the node is assigned any IP addresses,
469 # This is problematic since before the node has public addresses the node might
470 # not be able to route traffic to the public networks.
471 # One solution is to have static public addresses assigned with routing
472 # in addition to the public address interfaces, thus guaranteeing that
473 # a node always can route traffic to the external network.
474 # This is the most simple solution but it uses up a large number of
475 # additional ip addresses.
477 # A more complex solution is NAT-GW.
478 # In this mode we only need one additional ip address for the cluster from
479 # the exsternal public network.
480 # One of the nodes in the cluster is elected to be hosting this ip address
481 # so it can reach the external services. This node is also configured
482 # to use NAT MASQUERADING for all traffic from the internal private network
483 # to the external network. This node is the NAT-GW node.
485 # All other nodes are set up with a default rote with a metric of 10 to point
486 # to the nat-gw node.
488 # The effect of this is that only when a node does not have a public address
489 # and thus no proper routes to the external world it will instead
490 # route all packets through the nat-gw node.
492 # CTDB_NATGW_NODES is the list of nodes that belong to this natgw group.
493 # You can have multiple natgw groups in one cluster but each node
494 # can only belong to one single natgw group.
496 # CTDB_NATGW_PUBLIC_IP=10.0.0.227/24
497 # CTDB_NATGW_PUBLIC_IFACE=eth0
498 # CTDB_NATGW_DEFAULT_GATEWAY=10.0.0.1
499 # CTDB_NATGW_PRIVATE_NETWORK=10.1.1.0/24
500 # CTDB_NATGW_NODES=/etc/ctdb/natgw_nodes
502 # Normally any node in the natgw group can act as the natgw master.
503 # In some configurations you may have special nodes that is a part of the
504 # cluster/natgw group, but where the node lacks connectivity to the
506 # For these cases, set this variable to make these nodes not able to
507 # become natgw master.
509 # CTDB_NATGW_SLAVE_ONLY=yes
510 </pre></div><div class="refsect2" title="CTDB_NATGW_PUBLIC_IP"><a name="id426266"></a><h3>CTDB_NATGW_PUBLIC_IP</h3><p>
511 This is an ip address in the public network that is used for all outgoing
512 traffic when the public addresses are not assigned.
513 This address will be assigned to one of the nodes in the cluster which
514 will masquerade all traffic for the other nodes.
516 Format of this parameter is IPADDRESS/NETMASK
517 </p></div><div class="refsect2" title="CTDB_NATGW_PUBLIC_IFACE"><a name="id426280"></a><h3>CTDB_NATGW_PUBLIC_IFACE</h3><p>
518 This is the physical interface where the CTDB_NATGW_PUBLIC_IP will be
519 assigned to. This should be an interface connected to the public network.
521 Format of this parameter is INTERFACE
522 </p></div><div class="refsect2" title="CTDB_NATGW_DEFAULT_GATEWAY"><a name="id426293"></a><h3>CTDB_NATGW_DEFAULT_GATEWAY</h3><p>
523 This is the default gateway to use on the node that is elected to host
524 the CTDB_NATGW_PUBLIC_IP. This is the default gateway on the public network.
526 Format of this parameter is IPADDRESS
527 </p></div><div class="refsect2" title="CTDB_NATGW_PRIVATE_NETWORK"><a name="id426306"></a><h3>CTDB_NATGW_PRIVATE_NETWORK</h3><p>
528 This is the network/netmask used for the interal private network.
530 Format of this parameter is IPADDRESS/NETMASK
531 </p></div><div class="refsect2" title="CTDB_NATGW_NODES"><a name="id426319"></a><h3>CTDB_NATGW_NODES</h3><p>
532 This is the list of all nodes that belong to the same NATGW group
533 as this node. The default is /etc/ctdb/natgw_nodes.
534 </p></div><div class="refsect2" title="Operation"><a name="id426329"></a><h3>Operation</h3><p>
535 When the NAT-GW functionality is used, one of the nodes is elected
536 to act as a NAT router for all the other nodes in the group when
537 they need to originate traffic to the external public network.
539 The NAT-GW node is assigned the CTDB_NATGW_PUBLIC_IP to the designated
540 interface and the provided default route. The NAT-GW is configured
541 to act as a router and to masquerade all traffic it receives from the
542 internal private network and which is destined to the external network(s).
544 All other nodes in the group are configured with a default route of
545 metric 10 pointing to the designated NAT GW node.
547 This is implemented in the 11.natgw eventscript. Please see the
548 eventscript for further information.
549 </p></div><div class="refsect2" title="Removing/Changing NATGW at runtime"><a name="id426354"></a><h3>Removing/Changing NATGW at runtime</h3><p>
550 The following are the procedures to change/remove a NATGW configuration
551 at runtime, without having to restart ctdbd.
553 If you want to remove NATGW completely from a node, use these steps:
554 </p><pre class="screen">
555 1, Run 'CTDB_BASE=/etc/ctdb /etc/ctdb/events.d/11.natgw removenatgw'
556 2, Then remove the configuration from /etc/sysconfig/ctdb
558 If you want to change the NATGW configuration on a node :
559 </p><pre class="screen">
560 1, Run 'CTDB_BASE=/etc/ctdb /etc/ctdb/events.d/11.natgw removenatgw'
561 2, Then change the configuration in /etc/sysconfig/ctdb
562 3, Run 'CTDB_BASE=/etc/ctdb /etc/ctdb/events.d/11.natgw updatenatgw'
563 </pre></div></div><div class="refsect1" title="NOTIFICATION SCRIPT"><a name="id426385"></a><h2>NOTIFICATION SCRIPT</h2><p>
564 Notification scripts are used with ctdb to have a call-out from ctdb
565 to a user-specified script when certain state changes occur in ctdb.
566 This is commonly to set up either sending SNMP traps or emails
567 when a node becomes unhealthy and similar.
569 This is activated by setting CTDB_NOTIFY_SCRIPT=<your script> in the
570 sysconfig file, or by adding --notification-script=<your script>.
572 See /etc/ctdb/notify.sh for an example script.
574 CTDB currently generates notifications on these state changes:
575 </p><div class="refsect2" title="unhealthy"><a name="id426409"></a><h3>unhealthy</h3><p>
576 This call-out is triggered when the node changes to UNHEALTHY state.
577 </p></div><div class="refsect2" title="healthy"><a name="id426418"></a><h3>healthy</h3><p>
578 This call-out is triggered when the node changes to HEALTHY state.
579 </p></div><div class="refsect2" title="startup"><a name="id426427"></a><h3>startup</h3><p>
580 This call-out is triggered when ctdb has started up and all managed services are up and running.
581 </p></div></div><div class="refsect1" title="ClamAV Daemon"><a name="id426438"></a><h2>ClamAV Daemon</h2><p>
582 CTDB has support to manage the popular anti-virus daemon ClamAV.
583 This support is implemented through the
584 eventscript : /etc/ctdb/events.d/31.clamd.
585 </p><div class="refsect2" title="Configuration"><a name="id426447"></a><h3>Configuration</h3><p>
586 Start by configuring CLAMAV normally and test that it works. Once this is
587 done, copy the configuration files over to all the nodes so that all nodes
588 share identical CLAMAV configurations.
589 Once this is done you can proceed with the intructions below to activate
590 CTDB support for CLAMAV.
592 First, to activate CLAMAV support in CTDB, edit /etc/sysconfig/ctdb and add the two lines :
593 </p><pre class="screen">
594 CTDB_MANAGES_CLAMD=yes
595 CTDB_CLAMD_SOCKET="/path/to/clamd.socket"
597 Second, activate the eventscript
598 </p><pre class="screen">
599 ctdb enablescript 31.clamd
601 Third, CTDB will now be starting and stopping this service accordingly,
602 so make sure that the system is not configured to start/stop this service
604 On RedHat systems you can disable the system starting/stopping CLAMAV automatically by running :
605 </p><pre class="screen">
609 Once you have restarted CTDBD, use
610 </p><pre class="screen">
613 and verify that the 31.clamd eventscript is listed and that it was executed successfully.
614 </p></div></div><div class="refsect1" title="SEE ALSO"><a name="id426497"></a><h2>SEE ALSO</h2><p>
616 <a class="ulink" href="http://ctdb.samba.org/" target="_top">http://ctdb.samba.org/</a>
617 </p></div><div class="refsect1" title="COPYRIGHT/LICENSE"><a name="id426509"></a><h2>COPYRIGHT/LICENSE</h2><div class="literallayout"><p><br>
618 Copyright (C) Andrew Tridgell 2007<br>
619 Copyright (C) Ronnie sahlberg 2007<br>
621 This program is free software; you can redistribute it and/or modify<br>
622 it under the terms of the GNU General Public License as published by<br>
623 the Free Software Foundation; either version 3 of the License, or (at<br>
624 your option) any later version.<br>
626 This program is distributed in the hope that it will be useful, but<br>
627 WITHOUT ANY WARRANTY; without even the implied warranty of<br>
628 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU<br>
629 General Public License for more details.<br>
631 You should have received a copy of the GNU General Public License<br>
632 along with this program; if not, see http://www.gnu.org/licenses/.<br>
633 </p></div></div></div></body></html>
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