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<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>ctdbd</title><meta name="generator" content="DocBook XSL Stylesheets V1.76.1"></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="idp199104"></a><h2>DESCRIPTION</h2><p>
ctdbd is the main ctdb daemon.
</p><p>
ctdbd provides a clustered version of the TDB database with automatic rebuild/recovery of the databases upon nodefailures.
</p><p>
Combined with a cluster filesystem ctdbd provides a full HA environment for services such as clustered Samba and NFS as well as other services.
</p><p>
ctdbd provides monitoring of all nodes in the cluster and automatically reconfigures the cluster and recovers upon node failures.
</p><p>
ctdbd is the main component in clustered Samba that provides a high-availability load-sharing CIFS server cluster.
</p></div><div class="refsect1" title="OPTIONS"><a name="idp201064"></a><h2>OPTIONS</h2><div class="variablelist"><dl><dt><span class="term">-? --help</span></dt><dd><p>
Print some help text to the screen.
</p></dd><dt><span class="term">-d --debug=<DEBUGLEVEL></span></dt><dd><p>
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.
</p></dd><dt><span class="term">--dbdir=<directory></span></dt><dd><p>
This is the directory on local storage where ctdbd keeps the local
copy of the TDB databases. This directory is local for each node and should not be stored on the shared cluster filesystem.
</p><p>
This directory would usually be /var/ctdb .
</p></dd><dt><span class="term">--dbdir-persistent=<directory></span></dt><dd><p>
This is the directory on local storage where ctdbd keeps the local
copy of the persistent TDB databases. This directory is local for each node and should not be stored on the shared cluster filesystem.
</p><p>
This directory would usually be /etc/ctdb/persistent .
</p></dd><dt><span class="term">--event-script-dir=<directory></span></dt><dd><p>
This option is used to specify the directory where the CTDB event
scripts are stored.
</p><p>
This will normally be /etc/ctdb/events.d which is part of the ctdb distribution.
</p></dd><dt><span class="term">-i --interactive</span></dt><dd><p>
By default ctdbd will detach itself from the shell and run in
the background as a daemon. This option makes ctdbd to start in interactive mode.
</p></dd><dt><span class="term">--listen=<address></span></dt><dd><p>
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.
</p><p>
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.
</p></dd><dt><span class="term">--logfile=<filename></span></dt><dd><p>
This is the file where ctdbd will write its log. This is usually /var/log/log.ctdb .
</p></dd><dt><span class="term">--lvs</span></dt><dd><p>
This option is used to activate the LVS capability on a CTDB node.
Please see the LVS section.
</p></dd><dt><span class="term">--nlist=<filename></span></dt><dd><p>
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.
</p><p>
This file is usually /etc/ctdb/nodes .
</p></dd><dt><span class="term">--no-lmaster</span></dt><dd><p>
This argument specifies that this node can NOT become an lmaster
for records in the database. This means that it will never show up
in the vnnmap. This feature is primarily used for making a cluster
span across a WAN link and use CTDB as a WAN-accelerator.
</p><p>
Please see the "remote cluster nodes" section for more information.
</p></dd><dt><span class="term">--no-recmaster</span></dt><dd><p>
This argument specifies that this node can NOT become a recmaster
for the database. This feature is primarily used for making a cluster
span across a WAN link and use CTDB as a WAN-accelerator.
</p><p>
Please see the "remote cluster nodes" section for more information.
</p></dd><dt><span class="term">--nosetsched</span></dt><dd><p>
This is a ctdbd debugging option. this option is only used when
debugging ctdbd.
</p><p>
Normally ctdb will change its scheduler to run as a real-time
process. This is the default mode for a normal ctdbd operation
to gurarantee that ctdbd always gets the cpu cycles that it needs.
</p><p>
This option is used to tell ctdbd to NOT run as a real-time process
and instead run ctdbd as a normal userspace process.
This is useful for debugging and when you want to run ctdbd under
valgrind or gdb. (You don't want to attach valgrind or gdb to a
real-time process.)
</p></dd><dt><span class="term">--notification-script=<filename></span></dt><dd><p>
This specifies a script which will be invoked by ctdb when certain
state changes occur in ctdbd and when you may want to trigger this
to run certain scripts.
</p><p>
This file is usually /etc/ctdb/notify.sh .
</p><p>
See the NOTIFICATION SCRIPT section below for more information.
</p></dd><dt><span class="term">--public_addresses=<filename></span></dt><dd><p>
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.
</p><p>
This is usually the file /etc/ctdb/public_addresses
</p></dd><dt><span class="term">--public-interface=<interface></span></dt><dd><p>
This option tells ctdb which interface to attach public-addresses
to and also where to attach the single-public-ip when used.
</p><p>
This is only required when using public ip addresses and only when
you don't specify the interface explicitly in /etc/ctdb/public_addresses or when you are using --single-public-ip.
</p><p>
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.
</p></dd><dt><span class="term">--reclock=<filename></span></dt><dd><p>
This is the name of the lock file stored of the shared cluster filesystem that ctdbd uses to prevent split brains from occuring.
This file must be stored on shared storage.
</p><p>
It is possible to run CTDB without a reclock file, but then there
will be no protection against split brain if the network becomes
partitioned. Using CTDB without a reclock file is strongly
discouraged.
</p></dd><dt><span class="term">--socket=<filename></span></dt><dd><p>
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.
</p><p>
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.
</p></dd><dt><span class="term">--start-as-disabled</span></dt><dd><p>
This makes the ctdb daemon to be DISABLED when it starts up.
</p><p>
As it is DISABLED it will not get any of the public ip addresses
allocated to it, and thus this allow you to start ctdb on a node
without causing any ip address to failover from other nodes onto
the new node.
</p><p>
When used, the administrator must keep track of when nodes start and
manually enable them again using the "ctdb enable" command, or else
the node will not host any services.
</p><p>
A node that is DISABLED will not host any services and will not be
reachable/used by any clients.
</p></dd><dt><span class="term">--start-as-stopped</span></dt><dd><p>
This makes the ctdb daemon to be STOPPED when it starts up.
</p><p>
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.
</p><p>
To restart and activate a STOPPED node, the command "ctdb continue" is used.
</p><p>
A node that is STOPPED will not host any services and will not be
reachable/used by any clients.
</p></dd><dt><span class="term">--syslog</span></dt><dd><p>
Send all log messages to syslog instead of to the ctdb logfile.
</p></dd><dt><span class="term">--log-ringbuf-size=<num-entries></span></dt><dd><p>
In addition to the normal loggign to a log file,
CTDBD also keeps a in-memory ringbuffer containing the most recent
log entries for all log levels (except DEBUG).
</p><p>
This is useful since it allows for keeping continuous logs to a file
at a reasonable non-verbose level, but shortly after an incident has
occured, a much more detailed log can be pulled from memory. This
can allow you to avoid having to reproduce an issue due to the
on-disk logs being of insufficient detail.
</p><p>
This in-memory ringbuffer contains a fixed number of the most recent
entries. This is settable at startup either through the
--log-ringbuf-size argument, or preferably by using
CTDB_LOG_RINGBUF_SIZE in the sysconfig file.
</p><p>
Use the "ctdb getlog" command to access this log.
</p></dd><dt><span class="term">--torture</span></dt><dd><p>
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.
</p><p>
You do NOT want to use this option unless you are developing and testing new functionality in ctdbd.
</p></dd><dt><span class="term">--transport=<STRING></span></dt><dd><p>
This option specifies which transport to use for ctdbd internode communications. The default is "tcp".
</p><p>
Currently only "tcp" is supported but "infiniband" might be
implemented in the future.
</p></dd><dt><span class="term">--usage</span></dt><dd><p>
Print useage information to the screen.
</p></dd></dl></div></div><div class="refsect1" title="Private vs Public addresses"><a name="idp90512"></a><h2>Private vs Public addresses</h2><p>
When used for ip takeover in a HA environment, each node in a ctdb
cluster has multiple ip addresses assigned to it. One private and one or more public.
</p><div class="refsect2" title="Private address"><a name="idp91136"></a><h3>Private address</h3><p>
This is the physical ip address of the node which is configured in
linux and attached to a physical interface. This address uniquely
identifies a physical node in the cluster and is the ip addresses
that ctdbd will use to communicate with the ctdbd daemons on the
other nodes in the cluster.
</p><p>
The private addresses are configured in /etc/ctdb/nodes
(unless the --nlist option is used) and contain one line for each
node in the cluster. Each line contains the private ip address for one
node in the cluster. This file must be the same on all nodes in the
cluster.
</p><p>
Since the private addresses are only available to the network when the
corresponding node is up and running you should not use these addresses
for clients to connect to services provided by the cluster. Instead
client applications should only attach to the public addresses since
these are guaranteed to always be available.
</p><p>
When using ip takeover, it is strongly recommended that the private
addresses are configured on a private network physically separated
from the rest of the network and that this private network is dedicated
to CTDB traffic.
</p>
Example /etc/ctdb/nodes for a four node cluster:
<pre class="screen">
10.1.1.1
10.1.1.2
10.1.1.3
10.1.1.4
</pre></div><div class="refsect2" title="Public address"><a name="idp94040"></a><h3>Public address</h3><p>
A public address on the other hand is not attached to an interface.
This address is managed by ctdbd itself and is attached/detached to
a physical node at runtime.
</p><p>
The ctdb cluster will assign/reassign these public addresses across the
available healthy nodes in the cluster. When one node fails, its public address
will be migrated to and taken over by a different node in the cluster
to ensure that all public addresses are always available to clients as
long as there are still nodes available capable of hosting this address.
</p><p>
These addresses are not physically attached to a specific node.
The 'ctdb ip' command can be used to view the current assignment of
public addresses and which physical node is currently serving it.
</p><p>
On each node this file contains a list of the public addresses that
this node is capable of hosting.
The list also contain the netmask and the
interface where this address should be attached for the case where you
may want to serve data out through multiple different interfaces.
</p>
Example /etc/ctdb/public_addresses for a node that can host 4 public addresses:
<pre class="screen">
11.1.1.1/24 eth0
11.1.1.2/24 eth0
11.1.2.1/24 eth1
11.1.2.2/24 eth1
</pre><p>
In most cases this file would be the same on all nodes in a cluster but
there are exceptions when one may want to use different files
on different nodes.
</p>
Example: 4 nodes partitioned into two subgroups :
<pre class="screen">
Node 0:/etc/ctdb/public_addresses
10.1.1.1/24 eth0
10.1.1.2/24 eth0
Node 1:/etc/ctdb/public_addresses
10.1.1.1/24 eth0
10.1.1.2/24 eth0
Node 2:/etc/ctdb/public_addresses
10.2.1.1/24 eth0
10.2.1.2/24 eth0
Node 3:/etc/ctdb/public_addresses
10.2.1.1/24 eth0
10.2.1.2/24 eth0
</pre><p>
In this example nodes 0 and 1 host two public addresses on the
10.1.1.x network while nodes 2 and 3 host two public addresses for the
10.2.1.x network.
</p><p>
Ip address 10.1.1.1 can be hosted by either of nodes 0 or 1 and will be
available to clients as long as at least one of these two nodes are
available.
If both nodes 0 and node 1 become unavailable 10.1.1.1 also becomes
unavailable. 10.1.1.1 can not be failed over to node 2 or node 3 since
these nodes do not have this ip address listed in their public
addresses file.
</p></div></div><div class="refsect1" title="Node status"><a name="idp98936"></a><h2>Node status</h2><p>
The current status of each node in the cluster can be viewed by the
'ctdb status' command.
</p><p>
There are five possible states for a node.
</p><p>
OK - This node is fully functional.
</p><p>
DISCONNECTED - This node could not be connected through the network
and is currently not particpating in the cluster. If there is a
public IP address associated with this node it should have been taken
over by a different node. No services are running on this node.
</p><p>
DISABLED - This node has been administratively disabled. This node is
still functional and participates in the CTDB cluster but its IP
addresses have been taken over by a different node and no services are
currently being hosted.
</p><p>
UNHEALTHY - A service provided by this node is malfunctioning and should
be investigated. The CTDB daemon itself is operational and participates
in the cluster. Its public IP address has been taken over by a different
node and no services are currently being hosted. All unhealthy nodes
should be investigated and require an administrative action to rectify.
</p><p>
BANNED - This node failed too many recovery attempts and has been banned
from participating in the cluster for a period of RecoveryBanPeriod
seconds. Any public IP address has been taken over by other nodes. This
node does not provide any services. All banned nodes should be
investigated and require an administrative action to rectify. This node
does not perticipate in the CTDB cluster but can still be communicated
with. I.e. ctdb commands can be sent to it.
</p><p>
STOPPED - A node that is stopped does not host any public ip addresses,
nor is it part of the VNNMAP. A stopped node can not become LVSMASTER,
RECMASTER or NATGW.
This node does not perticipate in the CTDB cluster but can still be
communicated with. I.e. ctdb commands can be sent to it.
</p></div><div class="refsect1" title="PUBLIC TUNABLES"><a name="idp102960"></a><h2>PUBLIC TUNABLES</h2><p>
These are the public tuneables that can be used to control how ctdb behaves.
</p><div class="refsect2" title="MaxRedirectCount"><a name="idp103592"></a><h3>MaxRedirectCount</h3><p>Default: 3</p><p>
If we are not the DMASTER and need to fetch a record across the network
we first send the request to the LMASTER after which the record
is passed onto the current DMASTER. If the DMASTER changes before
the request has reached that node, the request will be passed onto the
"next" DMASTER. For very hot records that migrate rapidly across the
cluster this can cause a request to "chase" the record for many hops
before it catches up with the record.
this is how many hops we allow trying to chase the DMASTER before we
switch back to the LMASTER again to ask for new directions.
</p><p>
When chasing a record, this is how many hops we will chase the record
for before going back to the LMASTER to ask for new guidance.
</p></div><div class="refsect2" title="SeqnumInterval"><a name="idp105312"></a><h3>SeqnumInterval</h3><p>Default: 1000</p><p>
Some databases have seqnum tracking enabled, so that samba will be able
to detect asynchronously when there has been updates to the database.
Everytime a database is updated its sequence number is increased.
</p><p>
This tunable is used to specify in 'ms' how frequently ctdb will
send out updates to remote nodes to inform them that the sequence
number is increased.
</p></div><div class="refsect2" title="ControlTimeout"><a name="idp106664"></a><h3>ControlTimeout</h3><p>Default: 60</p><p>
This is the default
setting for timeout for when sending a control message to either the
local or a remote ctdb daemon.
</p></div><div class="refsect2" title="TraverseTimeout"><a name="idp107552"></a><h3>TraverseTimeout</h3><p>Default: 20</p><p>
This setting controls how long we allow a traverse process to run.
After this timeout triggers, the main ctdb daemon will abort the
traverse if it has not yet finished.
</p></div><div class="refsect2" title="KeepaliveInterval"><a name="idp108488"></a><h3>KeepaliveInterval</h3><p>Default: 5</p><p>
How often in seconds should the nodes send keepalives to eachother.
</p></div><div class="refsect2" title="KeepaliveLimit"><a name="idp109320"></a><h3>KeepaliveLimit</h3><p>Default: 5</p><p>
After how many keepalive intervals without any traffic should a node
wait until marking the peer as DISCONNECTED.
</p><p>
If a node has hung, it can thus take KeepaliveInterval*(KeepaliveLimit+1)
seconds before we determine that the node is DISCONNECTED and that we
require a recovery. This limitshould not be set too high since we want
a hung node to be detectec, and expunged from the cluster well before
common CIFS timeouts (45-90 seconds) kick in.
</p></div><div class="refsect2" title="RecoverTimeout"><a name="idp110760"></a><h3>RecoverTimeout</h3><p>Default: 20</p><p>
This is the default setting for timeouts for controls when sent from the
recovery daemon. We allow longer control timeouts from the recovery daemon
than from normal use since the recovery dameon often use controls that
can take a lot longer than normal controls.
</p></div><div class="refsect2" title="RecoverInterval"><a name="idp111800"></a><h3>RecoverInterval</h3><p>Default: 1</p><p>
How frequently in seconds should the recovery daemon perform the
consistency checks that determine if we need to perform a recovery or not.
</p></div><div class="refsect2" title="ElectionTimeout"><a name="idp112704"></a><h3>ElectionTimeout</h3><p>Default: 3</p><p>
When electing a new recovery master, this is how many seconds we allow
the election to take before we either deem the election finished
or we fail the election and start a new one.
</p></div><div class="refsect2" title="TakeoverTimeout"><a name="idp113656"></a><h3>TakeoverTimeout</h3><p>Default: 9</p><p>
This is how many seconds we allow controls to take for IP failover events.
</p></div><div class="refsect2" title="MonitorInterval"><a name="idp114496"></a><h3>MonitorInterval</h3><p>Default: 15</p><p>
How often should ctdb run the event scripts to check for a nodes health.
</p></div><div class="refsect2" title="TickleUpdateInterval"><a name="idp115328"></a><h3>TickleUpdateInterval</h3><p>Default: 20</p><p>
How often will ctdb record and store the "tickle" information used to
kickstart stalled tcp connections after a recovery.
</p></div><div class="refsect2" title="EventScriptTimeout"><a name="idp116192"></a><h3>EventScriptTimeout</h3><p>Default: 20</p><p>
How long should ctdb let an event script run before aborting it and
marking the node unhealthy.
</p></div><div class="refsect2" title="EventScriptTimeoutCount"><a name="idp117056"></a><h3>EventScriptTimeoutCount</h3><p>Default: 1</p><p>
How many events in a row needs to timeout before we flag the node UNHEALTHY.
This setting is useful if your scripts can not be written so that they
do not hang for benign reasons.
</p></div><div class="refsect2" title="EventScriptUnhealthyOnTimeout"><a name="idp117984"></a><h3>EventScriptUnhealthyOnTimeout</h3><p>Default: 0</p><p>
This setting can be be used to make ctdb never become UNHEALTHY if your
eventscripts keep hanging/timing out.
</p></div><div class="refsect2" title="RecoveryGracePeriod"><a name="idp118832"></a><h3>RecoveryGracePeriod</h3><p>Default: 120</p><p>
During recoveries, if a node has not caused recovery failures during the
last grace period, any records of transgressions that the node has caused
recovery failures will be forgiven. This resets the ban-counter back to
zero for that node.
</p></div><div class="refsect2" title="RecoveryBanPeriod"><a name="idp119856"></a><h3>RecoveryBanPeriod</h3><p>Default: 300</p><p>
If a node becomes banned causing repetitive recovery failures. The node will
eventually become banned from the cluster.
This controls how long the culprit node will be banned from the cluster
before it is allowed to try to join the cluster again.
Don't set to small. A node gets banned for a reason and it is usually due
to real problems with the node.
</p></div><div class="refsect2" title="DatabaseHashSize"><a name="idp121384"></a><h3>DatabaseHashSize</h3><p>Default: 100001</p><p>
Size of the hash chains for the local store of the tdbs that ctdb manages.
</p></div><div class="refsect2" title="DatabaseMaxDead"><a name="idp122232"></a><h3>DatabaseMaxDead</h3><p>Default: 5</p><p>
How many dead records per hashchain in the TDB database do we allow before
the freelist needs to be processed.
</p></div><div class="refsect2" title="RerecoveryTimeout"><a name="idp123112"></a><h3>RerecoveryTimeout</h3><p>Default: 10</p><p>
Once a recovery has completed, no additional recoveries are permitted
until this timeout has expired.
</p></div><div class="refsect2" title="EnableBans"><a name="idp123976"></a><h3>EnableBans</h3><p>Default: 1</p><p>
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 unless you
know what you are doing.
</p></div><div class="refsect2" title="DeterministicIPs"><a name="idp124904"></a><h3>DeterministicIPs</h3><p>Default: 0</p><p>
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.
</p><p>
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.
</p></div><div class="refsect2" title="LCP2PublicIPs"><a name="idp126448"></a><h3>LCP2PublicIPs</h3><p>Default: 1</p><p>
When enabled this switches ctdb to use the LCP2 ip allocation
algorithm.
</p></div><div class="refsect2" title="ReclockPingPeriod"><a name="idp127288"></a><h3>ReclockPingPeriod</h3><p>Default: x</p><p>
Obsolete
</p></div><div class="refsect2" title="NoIPFailback"><a name="idp128056"></a><h3>NoIPFailback</h3><p>Default: 0</p><p>
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.
</p><p>
Use with caution! Normally when a node becomes available to the cluster
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.
</p><p>
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.
</p></div><div class="refsect2" title="DisableIPFailover"><a name="idp130224"></a><h3>DisableIPFailover</h3><p>Default: 0</p><p>
When enabled, ctdb will not perform failover or failback. Even if a
node fails while holding public IPs, ctdb will not recover the IPs or
assign them to another node.
</p><p>
When you enable this tunable, CTDB will no longer attempt to recover
the cluster by failing IP addresses over to other nodes. This leads to
a service outage until the administrator has manually performed failover
to replacement nodes using the 'ctdb moveip' command.
</p></div><div class="refsect2" title="NoIPTakeover"><a name="idp131648"></a><h3>NoIPTakeover</h3><p>Default: 0</p><p>
When set to 1, ctdb will allow ip addresses to be failed over onto this
node. Any ip addresses that the node currently hosts will remain on the
node but no new ip addresses can be failed over onto the node.
</p></div><div class="refsect2" title="DBRecordCountWarn"><a name="idp132624"></a><h3>DBRecordCountWarn</h3><p>Default: 100000</p><p>
When set to non-zero, ctdb will log a warning when we try to recover a
database with more than this many records. This will produce a warning
if a database grows uncontrollably with orphaned records.
</p></div><div class="refsect2" title="DBRecordSizeWarn"><a name="idp133600"></a><h3>DBRecordSizeWarn</h3><p>Default: 10000000</p><p>
When set to non-zero, ctdb will log a warning when we try to recover a
database where a single record is bigger than this. This will produce
a warning if a database record grows uncontrollably with orphaned
sub-records.
</p></div><div class="refsect2" title="DBSizeWarn"><a name="idp134600"></a><h3>DBSizeWarn</h3><p>Default: 1000000000</p><p>
When set to non-zero, ctdb will log a warning when we try to recover a
database bigger than this. This will produce
a warning if a database grows uncontrollably.
</p></div><div class="refsect2" title="VerboseMemoryNames"><a name="idp135528"></a><h3>VerboseMemoryNames</h3><p>Default: 0</p><p>
This feature consumes additional memory. when used the talloc library
will create more verbose names for all talloc allocated objects.
</p></div><div class="refsect2" title="RecdPingTimeout"><a name="idp136432"></a><h3>RecdPingTimeout</h3><p>Default: 60</p><p>
If the main dameon has not heard a "ping" from the recovery dameon for
this many seconds, the main dameon will log a message that the recovery
daemon is potentially hung.
</p></div><div class="refsect2" title="RecdFailCount"><a name="idp137376"></a><h3>RecdFailCount</h3><p>Default: 10</p><p>
If the recovery daemon has failed to ping the main dameon for this many
consecutive intervals, the main daemon will consider the recovery daemon
as hung and will try to restart it to recover.
</p></div><div class="refsect2" title="LogLatencyMs"><a name="idp138336"></a><h3>LogLatencyMs</h3><p>Default: 0</p><p>
When set to non-zero, this will make the main daemon log any operation that
took longer than this value, in 'ms', to complete.
These include "how long time a lockwait child process needed",
"how long time to write to a persistent database" but also
"how long did it take to get a response to a CALL from a remote node".
</p></div><div class="refsect2" title="RecLockLatencyMs"><a name="idp139432"></a><h3>RecLockLatencyMs</h3><p>Default: 1000</p><p>
When using a reclock file for split brain prevention, if set to non-zero
this tunable will make the recovery dameon log a message if the fcntl()
call to lock/testlock the recovery file takes longer than this number of
ms.
</p></div><div class="refsect2" title="RecoveryDropAllIPs"><a name="idp140440"></a><h3>RecoveryDropAllIPs</h3><p>Default: 120</p><p>
If we have been stuck in recovery, or stopped, or banned, mode for
this many seconds we will force drop all held public addresses.
</p></div><div class="refsect2" title="verifyRecoveryLock"><a name="idp141344"></a><h3>verifyRecoveryLock</h3><p>Default: 1</p><p>
Should we take a fcntl() lock on the reclock file to verify that we are the
sole recovery master node on the cluster or not.
</p></div><div class="refsect2" title="DeferredAttachTO"><a name="idp142232"></a><h3>DeferredAttachTO</h3><p>Default: 120</p><p>
When databases are frozen we do not allow clients to attach to the
databases. Instead of returning an error immediately to the application
the attach request from the client is deferred until the database
becomes available again at which stage we respond to the client.
</p><p>
This timeout controls how long we will defer the request from the client
before timing it out and returning an error to the client.
</p></div><div class="refsect2" title="HopcountMakeSticky"><a name="idp3179992"></a><h3>HopcountMakeSticky</h3><p>Default: 50</p><p>
If the database is set to 'STICKY' mode, using the 'ctdb setdbsticky'
command, any record that is seen as very hot and migrating so fast that
hopcount surpasses 50 is set to become a STICKY record for StickyDuration
seconds. This means that after each migration the record will be kept on
the node and prevented from being migrated off the node.
</p><p>
This setting allows to try to identify such records and stop them from
migrating across the cluster so fast. This will improve performance for
certain workloads, such as locking.tdb if many clients are opening/closing
the same file concurrently.
</p></div><div class="refsect2" title="StickyDuration"><a name="idp3181552"></a><h3>StickyDuration</h3><p>Default: 600</p><p>
Once a record has been found to be fetch-lock hot and has been flagged to
become STICKY, this is for how long, in seconds, the record will be
flagged as a STICKY record.
</p></div><div class="refsect2" title="StickyPindown"><a name="idp3182456"></a><h3>StickyPindown</h3><p>Default: 200</p><p>
Once a STICKY record has been migrated onto a node, it will be pinned down
on that node for this number of ms. Any request from other nodes to migrate
the record off the node will be deferred until the pindown timer expires.
</p></div><div class="refsect2" title="MaxLACount"><a name="idp3183408"></a><h3>MaxLACount</h3><p>Default: 20</p><p>
When record content is fetched from a remote node, if it is only for
reading the record, pass back the content of the record but do not yet
migrate the record. Once MaxLACount identical requests from the
same remote node have been seen will the record be forcefully migrated
onto the requesting node. This reduces the amount of migration for a
database read-mostly workload at the expense of more frequent network
roundtrips.
</p></div><div class="refsect2" title="StatHistoryInterval"><a name="idp3184584"></a><h3>StatHistoryInterval</h3><p>Default: 1</p><p>
Granularity of the statistics collected in the statistics history.
</p></div><div class="refsect2" title="AllowClientDBAttach"><a name="idp3185376"></a><h3>AllowClientDBAttach</h3><p>Default: 1</p><p>
When set to 0, clients are not allowed to attach to any databases.
This can be used to temporarily block any new processes from attaching
to and accessing the databases.
</p></div><div class="refsect2" title="RecoverPDBBySeqNum"><a name="idp3186272"></a><h3>RecoverPDBBySeqNum</h3><p>Default: 0</p><p>
When set to non-zero, this will change how the recovery process for
persistent databases ar performed. By default, when performing a database
recovery, for normal as for persistent databases, recovery is
record-by-record and recovery process simply collects the most recent
version of every individual record.
</p><p>
When set to non-zero, persistent databases will instead be recovered as
a whole db and not by individual records. The node that contains the
highest value stored in the record "__db_sequence_number__" is selected
and the copy of that nodes database is used as the recovered database.
</p></div><div class="refsect2" title="FetchCollapse"><a name="idp3187824"></a><h3>FetchCollapse</h3><p>Default: 1</p><p>
When many clients across many nodes try to access the same record at the
same time this can lead to a fetch storm where the record becomes very
active and bounces between nodes very fast. This leads to high CPU
utilization of the ctdbd daemon, trying to bounce that record around
very fast, and poor performance.
</p><p>
This parameter is used to activate a fetch-collapse. A fetch-collapse
is when we track which records we have requests in flight so that we only
keep one request in flight from a certain node, even if multiple smbd
processes are attemtping to fetch the record at the same time. This
can improve performance and reduce CPU utilization for certain
workloads.
</p><p>
This timeout controls if we should collapse multiple fetch operations
of the same record into a single request and defer all duplicates or not.
</p></div></div><div class="refsect1" title="LVS"><a name="idp3190272"></a><h2>LVS</h2><p>
LVS is a mode where CTDB presents one single IP address for the entire
cluster. This is an alternative to using public IP addresses and round-robin
DNS to loadbalance clients across the cluster.
</p><p>
This is similar to using a layer-4 loadbalancing switch but with some restrictions.
</p><p>
In this mode the cluster select a set of nodes in the cluster and loadbalance
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
all LVS capable nodes regardless of health status.
LVS will however never loadbalance traffic to nodes that are BANNED,
STOPPED, DISABLED or DISCONNECTED. The "ctdb lvs" command is used to show
which nodes are currently load-balanced across.
</p><p>
One of the these nodes are elected as the LVSMASTER. This node receives all
traffic from clients coming in to the LVS address and multiplexes it
across the internal network to one of the nodes that LVS is using.
When responding to the client, that node will send the data back
directly to the client, bypassing the LVSMASTER node.
The command "ctdb lvsmaster" will show which node is the current
LVSMASTER.
</p><p>
The path used for a client i/o is thus :
</p><pre class="screen">
(1) Client sends request packet to LVSMASTER
(2) LVSMASTER passes the request on to one node across the internal network.
(3) Selected node processes the request.
(4) Node responds back to client.
</pre><p>
</p><p>
This means that all incoming traffic to the cluster will pass through
one physical node, which limits scalability. You can send more data to the
LVS address that one physical node can multiplex. This means that you
should not use LVS if your I/O pattern is write-intensive since you will be
limited in the available network bandwidth that node can handle.
LVS does work wery well for read-intensive workloads where only smallish
READ requests are going through the LVSMASTER bottleneck and the majority
of the traffic volume (the data in the read replies) goes straight from
the processing node back to the clients. For read-intensive i/o patterns you can acheive very high throughput rates in this mode.
</p><p>
Note: you can use LVS and public addresses at the same time.
</p><div class="refsect2" title="Configuration"><a name="idp3194584"></a><h3>Configuration</h3><p>
To activate LVS on a CTDB node you must specify CTDB_PUBLIC_INTERFACE and
CTDB_LVS_PUBLIC_ADDRESS in /etc/sysconfig/ctdb.
</p><p>
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.
</p><p>
Example:
</p><pre class="screen">
CTDB_PUBLIC_INTERFACE=eth0
CTDB_LVS_PUBLIC_IP=10.0.0.237
</pre><p>
</p></div><p>
If you use LVS, you must still have a real/permanent address configured
for the public interface on each node. This address must be routable
and the cluster nodes must be configured so that all traffic back to client
hosts are routed through this interface. This is also required in order
to allow samba/winbind on the node to talk to the domain controller.
(we can not use the lvs IP address to initiate outgoing traffic)
</p><p>
I.e. make sure that you can "ping" both the domain controller and also
all of the clients from the node BEFORE you enable LVS. Also make sure
that when you ping these hosts that the traffic is routed out through the
eth0 interface.
</p></div><div class="refsect1" title="REMOTE CLUSTER NODES"><a name="idp3197376"></a><h2>REMOTE CLUSTER NODES</h2><p>
It is possible to have a CTDB cluster that spans across a WAN link.
For example where you have a CTDB cluster in your datacentre but you also
want to have one additional CTDB node located at a remote branch site.
This is similar to how a WAN accelerator works but with the difference
that while a WAN-accelerator often acts as a Proxy or a MitM, in
the ctdb remote cluster node configuration the Samba instance at the remote site
IS the genuine server, not a proxy and not a MitM, and thus provides 100%
correct CIFS semantics to clients.
</p><p>
See the cluster as one single multihomed samba server where one of
the NICs (the remote node) is very far away.
</p><p>
NOTE: This does require that the cluster filesystem you use can cope
with WAN-link latencies. Not all cluster filesystems can handle
WAN-link latencies! Whether this will provide very good WAN-accelerator
performance or it will perform very poorly depends entirely
on how optimized your cluster filesystem is in handling high latency
for data and metadata operations.
</p><p>
To activate a node as being a remote cluster node you need to set
the following two parameters in /etc/sysconfig/ctdb for the remote node:
</p><pre class="screen">
CTDB_CAPABILITY_LMASTER=no
CTDB_CAPABILITY_RECMASTER=no
</pre><p>
</p><p>
Verify with the command "ctdb getcapabilities" that that node no longer
has the recmaster or the lmaster capabilities.
</p></div><div class="refsect1" title="NAT-GW"><a name="idp3200392"></a><h2>NAT-GW</h2><p>
Sometimes it is desireable to run services on the CTDB node which will
need to originate outgoing traffic to external servers. This might
be contacting NIS servers, LDAP servers etc. etc.
</p><p>
This can sometimes be problematic since there are situations when a
node does not have any public ip addresses assigned. This could
be due to the nobe just being started up and no addresses have been
assigned yet or it could be that the node is UNHEALTHY in which
case all public addresses have been migrated off.
</p><p>
If then the service status of CTDB depends on such services being
able to always being able to originate traffic to external resources
this becomes extra troublesome. The node might be UNHEALTHY because
the service can not be reached, and the service can not be reached
because the node is UNHEALTHY.
</p><p>
There are two ways to solve this problem. The first is by assigning a
static ip address for one public interface on every node which will allow
every node to be able to route traffic to the public network even
if there are no public addresses assigned to the node.
This is the simplest way but it uses up a lot of ip addresses since you
have to assign both static and also public addresses to each node.
</p><div class="refsect2" title="NAT-GW"><a name="idp3202792"></a><h3>NAT-GW</h3><p>
A second way is to use the built in NAT-GW feature in CTDB.
With NAT-GW you assign one public NATGW address for each natgw group.
Each NATGW group is a set of nodes in the cluster that shares the same
NATGW address to talk to the outside world. Normally there would only be
one NATGW group spanning the entire cluster, but in situations where one
ctdb cluster spans multiple physical sites it is useful to have one
NATGW group for each of the two sites.
</p><p>
There can be multiple NATGW groups in one cluster but each node can only
be member of one NATGW group.
</p><p>
In each NATGW group, one of the nodes is designated the NAT Gateway
through which all traffic that is originated by nodes in this group
will be routed through if a public addresses are not available.
</p></div><div class="refsect2" title="Configuration"><a name="idp3204560"></a><h3>Configuration</h3><p>
NAT-GW is configured in /etc/sysconfigctdb by setting the following
variables:
</p><pre class="screen">
# NAT-GW configuration
# Some services running on nthe CTDB node may need to originate traffic to
# remote servers before the node is assigned any IP addresses,
# This is problematic since before the node has public addresses the node might
# not be able to route traffic to the public networks.
# One solution is to have static public addresses assigned with routing
# in addition to the public address interfaces, thus guaranteeing that
# a node always can route traffic to the external network.
# This is the most simple solution but it uses up a large number of
# additional ip addresses.
#
# A more complex solution is NAT-GW.
# In this mode we only need one additional ip address for the cluster from
# the exsternal public network.
# One of the nodes in the cluster is elected to be hosting this ip address
# so it can reach the external services. This node is also configured
# to use NAT MASQUERADING for all traffic from the internal private network
# to the external network. This node is the NAT-GW node.
#
# All other nodes are set up with a default rote with a metric of 10 to point
# to the nat-gw node.
#
# The effect of this is that only when a node does not have a public address
# and thus no proper routes to the external world it will instead
# route all packets through the nat-gw node.
#
# CTDB_NATGW_NODES is the list of nodes that belong to this natgw group.
# You can have multiple natgw groups in one cluster but each node
# can only belong to one single natgw group.
#
# CTDB_NATGW_PUBLIC_IP=10.0.0.227/24
# CTDB_NATGW_PUBLIC_IFACE=eth0
# CTDB_NATGW_DEFAULT_GATEWAY=10.0.0.1
# CTDB_NATGW_PRIVATE_NETWORK=10.1.1.0/24
# CTDB_NATGW_NODES=/etc/ctdb/natgw_nodes
#
# Normally any node in the natgw group can act as the natgw master.
# In some configurations you may have special nodes that is a part of the
# cluster/natgw group, but where the node lacks connectivity to the
# public network.
# For these cases, set this variable to make these nodes not able to
# become natgw master.
#
# CTDB_NATGW_SLAVE_ONLY=yes
</pre></div><div class="refsect2" title="CTDB_NATGW_PUBLIC_IP"><a name="idp3207544"></a><h3>CTDB_NATGW_PUBLIC_IP</h3><p>
This is an ip address in the public network that is used for all outgoing
traffic when the public addresses are not assigned.
This address will be assigned to one of the nodes in the cluster which
will masquerade all traffic for the other nodes.
</p><p>
Format of this parameter is IPADDRESS/NETMASK
</p></div><div class="refsect2" title="CTDB_NATGW_PUBLIC_IFACE"><a name="idp3208592"></a><h3>CTDB_NATGW_PUBLIC_IFACE</h3><p>
This is the physical interface where the CTDB_NATGW_PUBLIC_IP will be
assigned to. This should be an interface connected to the public network.
</p><p>
Format of this parameter is INTERFACE
</p></div><div class="refsect2" title="CTDB_NATGW_DEFAULT_GATEWAY"><a name="idp3209520"></a><h3>CTDB_NATGW_DEFAULT_GATEWAY</h3><p>
This is the default gateway to use on the node that is elected to host
the CTDB_NATGW_PUBLIC_IP. This is the default gateway on the public network.
</p><p>
Format of this parameter is IPADDRESS
</p></div><div class="refsect2" title="CTDB_NATGW_PRIVATE_NETWORK"><a name="idp3210456"></a><h3>CTDB_NATGW_PRIVATE_NETWORK</h3><p>
This is the network/netmask used for the interal private network.
</p><p>
Format of this parameter is IPADDRESS/NETMASK
</p></div><div class="refsect2" title="CTDB_NATGW_NODES"><a name="idp3211312"></a><h3>CTDB_NATGW_NODES</h3><p>
This is the list of all nodes that belong to the same NATGW group
as this node. The default is /etc/ctdb/natgw_nodes.
</p></div><div class="refsect2" title="Operation"><a name="idp3211968"></a><h3>Operation</h3><p>
When the NAT-GW functionality is used, one of the nodes is elected
to act as a NAT router for all the other nodes in the group when
they need to originate traffic to the external public network.
</p><p>
The NAT-GW node is assigned the CTDB_NATGW_PUBLIC_IP to the
specified interface and the provided default route. Given that
the NAT-GW mechanism acts as a last resort, its default route is
added with a metric of 10 so that it can coexist with other
configured static routes. The NAT-GW is configured to act as a
router and to masquerade all traffic it receives from the
internal private network and which is destined to the external
network(s).
</p><p>
All other nodes in the group are configured with a default route of
metric 10 pointing to the designated NAT GW node.
</p><p>
This is implemented in the 11.natgw eventscript. Please see the
eventscript for further information.
</p></div><div class="refsect2" title="Removing/Changing NATGW at runtime"><a name="idp3214056"></a><h3>Removing/Changing NATGW at runtime</h3><p>
The following are the procedures to change/remove a NATGW configuration
at runtime, without having to restart ctdbd.
</p><p>
If you want to remove NATGW completely from a node, use these steps:
</p><pre class="screen">
1, Run 'CTDB_BASE=/etc/ctdb /etc/ctdb/events.d/11.natgw removenatgw'
2, Then remove the configuration from /etc/sysconfig/ctdb
</pre><p>
If you want to change the NATGW configuration on a node :
</p><pre class="screen">
1, Run 'CTDB_BASE=/etc/ctdb /etc/ctdb/events.d/11.natgw removenatgw'
2, Then change the configuration in /etc/sysconfig/ctdb
3, Run 'CTDB_BASE=/etc/ctdb /etc/ctdb/events.d/11.natgw updatenatgw'
</pre></div></div><div class="refsect1" title="POLICY ROUTING"><a name="idp3216304"></a><h2>POLICY ROUTING</h2><p>
A node running CTDB may be a component of a complex network
topology. In particular, public addresses may be spread across
several different networks (or VLANs) and it may not be possible
to route packets from these public addresses via the system's
default route. Therefore, CTDB has support for policy routing
via the 13.per_ip_routing eventscript. This allows routing to
be specified for packets sourced from each public address. The
routes are added and removed as CTDB moves public addresses
between nodes.
</p><div class="refsect2" title="Configuration variables"><a name="idp3217400"></a><h3>Configuration variables</h3><p>
There are 4 configuration variables related to policy routing:
</p><div class="variablelist"><dl><dt><span class="term"><code class="varname">CTDB_PER_IP_ROUTING_CONF</code></span></dt><dd><p>
The name of a configuration file that specifies the
desired routes for each source address. The configuration
file format is discussed below. A recommended value is
<code class="filename">/etc/ctdb/policy_routing</code>.
</p><p>
The special value <code class="constant">__auto_link_local__</code>
indicates that no configuration file is provided and that
CTDB should generate reasonable link-local routes for each
public address.
</p></dd><dt><span class="term"><code class="varname">CTDB_PER_IP_ROUTING_RULE_PREF</code></span></dt><dd><p>
This sets the priority (or preference) for the routing
rules that are added by CTDB.
</p><p>
This should be (strictly) greater than 0 and (strictly)
less than 32766. A priority of 100 is recommended, unless
this conflicts with a priority already in use on the
system. See ip(8) for more details.
</p></dd><dt><span class="term">
<code class="varname">CTDB_PER_IP_ROUTING_TABLE_ID_LOW</code>,
<code class="varname">CTDB_PER_IP_ROUTING_TABLE_ID_HIGH</code>
</span></dt><dd><p>
CTDB determines a unique routing table number to use for
the routing related to each public address. These
variables indicate the minimum and maximum routing table
numbers that are used.
</p><p>
The ip command uses some reserved routing table numbers
below 255. Therefore, CTDB_PER_IP_ROUTING_TABLE_ID_LOW
should be (strictly) greater than 255. 1000 and 9000
are recommended values, unless this range conflicts with
routing tables numbers already in use on the system.
</p><p>
CTDB uses the standard file
<code class="filename">/etc/iproute2/rt_tables</code> to maintain
a mapping between the routing table numbers and labels.
The label for a public address <addr;gt; will look
like ctdb.<addr>. This means that the associated
rules and routes are easy to read (and manipulate).
</p></dd></dl></div></div><div class="refsect2" title="Configuration file"><a name="idp3224576"></a><h3>Configuration file</h3><p>
The format of each line is:
</p><pre class="screen">
<public_address> <network> [ <gateway> ]
</pre><p>
Leading whitespace is ignored and arbitrary whitespace may be
used as a separator. Lines that have a "public address" item
that doesn't match an actual public address are ignored. This
means that comment lines can be added using a leading
character such as '#', since this will never match an IP
address.
</p><p>
A line without a gateway indicates a link local route.
</p><p>
For example, consider the configuration line:
</p><pre class="screen">
192.168.1.99 192.168.1.1/24
</pre><p>
If the corresponding public_addresses line is:
</p><pre class="screen">
192.168.1.99/24 eth2,eth3
</pre><p>
<code class="varname">CTDB_PER_IP_ROUTING_RULE_PREF</code> is 100, and
CTDB adds the address to eth2 then the following routing
information is added:
</p><pre class="screen">
ip rule add from 192.168.1.99 pref 100 table ctdb.192.168.1.99
ip route add 192.168.1.0/24 dev eth2 table ctdb.192.168.1.99
</pre><p>
This causes traffic from 192.168.1.1 to 192.168.1.0/24 go via
eth2.
</p><p>
The <span class="command"><strong>ip rule</strong></span> command will show (something
like - depending on other public addresses and other routes on
the system):
</p><pre class="screen">
0: from all lookup local
100: from 192.168.1.99 lookup ctdb.192.168.1.99
32766: from all lookup main
32767: from all lookup default
</pre><p>
<span class="command"><strong>ip route show table ctdb.192.168.1.99</strong></span> will show:
</p><pre class="screen">
192.168.1.0/24 dev eth2 scope link
</pre><p>
The usual use for a line containing a gateway is to add a
default route corresponding to a particular source address.
Consider this line of configuration:
</p><pre class="screen">
192.168.1.99 0.0.0.0/0 192.168.1.1
</pre><p>
In the situation described above this will cause an extra
routing command to be executed:
</p><pre class="screen">
ip route add 0.0.0.0/0 via 192.168.1.1 dev eth2 table ctdb.192.168.1.99
</pre><p>
With both configuration lines, <span class="command"><strong>ip route show table
ctdb.192.168.1.99</strong></span> will show:
</p><pre class="screen">
192.168.1.0/24 dev eth2 scope link
default via 192.168.1.1 dev eth2
</pre></div><div class="refsect2" title="Example configuration"><a name="idp3233304"></a><h3>Example configuration</h3><p>
Here is a more complete example configuration.
</p><pre class="screen">
/etc/ctdb/public_addresses:
192.168.1.98 eth2,eth3
192.168.1.99 eth2,eth3
/etc/ctdb/policy_routing:
192.168.1.98 192.168.1.0/24
192.168.1.98 192.168.200.0/24 192.168.1.254
192.168.1.98 0.0.0.0/0 192.168.1.1
192.168.1.99 192.168.1.0/24
192.168.1.99 192.168.200.0/24 192.168.1.254
192.168.1.99 0.0.0.0/0 192.168.1.1
</pre><p>
The routes local packets as expected, the default route is as
previously discussed, but packets to 192.168.200.0/24 are
routed via the alternate gateway 192.168.1.254.
</p></div></div><div class="refsect1" title="NOTIFICATION SCRIPT"><a name="idp3235048"></a><h2>NOTIFICATION SCRIPT</h2><p>
Notification scripts are used with ctdb to have a call-out from ctdb
to a user-specified script when certain state changes occur in ctdb.
This is commonly to set up either sending SNMP traps or emails
when a node becomes unhealthy and similar.
</p><p>
This is activated by setting CTDB_NOTIFY_SCRIPT=<your script> in the
sysconfig file, or by adding --notification-script=<your script>.
</p><p>
See /etc/ctdb/notify.sh for an example script.
</p><p>
CTDB currently generates notifications on these state changes:
</p><div class="refsect2" title="unhealthy"><a name="idp3236848"></a><h3>unhealthy</h3><p>
This call-out is triggered when the node changes to UNHEALTHY state.
</p></div><div class="refsect2" title="healthy"><a name="idp3237448"></a><h3>healthy</h3><p>
This call-out is triggered when the node changes to HEALTHY state.
</p></div><div class="refsect2" title="startup"><a name="idp3238048"></a><h3>startup</h3><p>
This call-out is triggered when ctdb has started up and all managed services are up and running.
</p></div></div><div class="refsect1" title="ClamAV Daemon"><a name="idp3238744"></a><h2>ClamAV Daemon</h2><p>
CTDB has support to manage the popular anti-virus daemon ClamAV.
This support is implemented through the
eventscript : /etc/ctdb/events.d/31.clamd.
</p><div class="refsect2" title="Configuration"><a name="idp3239352"></a><h3>Configuration</h3><p>
Start by configuring CLAMAV normally and test that it works. Once this is
done, copy the configuration files over to all the nodes so that all nodes
share identical CLAMAV configurations.
Once this is done you can proceed with the intructions below to activate
CTDB support for CLAMAV.
</p><p>
First, to activate CLAMAV support in CTDB, edit /etc/sysconfig/ctdb and add the two lines :
</p><pre class="screen">
CTDB_MANAGES_CLAMD=yes
CTDB_CLAMD_SOCKET="/path/to/clamd.socket"
</pre><p>
Second, activate the eventscript
</p><pre class="screen">
ctdb enablescript 31.clamd
</pre><p>
Third, CTDB will now be starting and stopping this service accordingly,
so make sure that the system is not configured to start/stop this service
automatically.
On RedHat systems you can disable the system starting/stopping CLAMAV automatically by running :
</p><pre class="screen">
chkconfig clamd off
</pre><p>
</p><p>
Once you have restarted CTDBD, use
</p><pre class="screen">
ctdb scriptstatus
</pre><p>
and verify that the 31.clamd eventscript is listed and that it was executed successfully.
</p></div></div><div class="refsect1" title="SEE ALSO"><a name="idp3242904"></a><h2>SEE ALSO</h2><p>
ctdb(1), onnode(1)
<a class="ulink" href="http://ctdb.samba.org/" target="_top">http://ctdb.samba.org/</a>
</p></div><div class="refsect1" title="COPYRIGHT/LICENSE"><a name="idp3243704"></a><h2>COPYRIGHT/LICENSE</h2><div class="literallayout"><p><br>
Copyright (C) Andrew Tridgell 2007<br>
Copyright (C) Ronnie sahlberg 2007<br>
<br>
This program is free software; you can redistribute it and/or modify<br>
it under the terms of the GNU General Public License as published by<br>
the Free Software Foundation; either version 3 of the License, or (at<br>
your option) any later version.<br>
<br>
This program is distributed in the hope that it will be useful, but<br>
WITHOUT ANY WARRANTY; without even the implied warranty of<br>
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU<br>
General Public License for more details.<br>
<br>
You should have received a copy of the GNU General Public License<br>
along with this program; if not, see http://www.gnu.org/licenses/.<br>
</p></div></div></div></body></html>
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