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       ctdbd - The CTDB cluster daemon



       ctdbd [-? --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] [--torture] [--transport=<STRING>] [--usage]


       ctdbd is the main ctdb daemon.

       ctdbd provides a clustered version of the TDB database with automatic
       rebuild/recovery of the databases upon nodefailures.

       Combined with a cluster filesystem ctdbd provides a full HA environment
       for services such as clustered Samba and NFS as well as other services.

       ctdbd provides monitoring of all nodes in the cluster and automatically
       reconfigures the cluster and recovers upon node failures.

       ctdbd is the main component in clustered Samba that provides a
       high-availability load-sharing CIFS server cluster.


       -? --help
           Print some help text to the screen.

       -d --debug=<DEBUGLEVEL>
           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.

           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.

           This directory would usually be /var/ctdb .

           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

           This directory would usually be /etc/ctdb/persistent .

           This option is used to specify the directory where the CTDB event
           scripts are stored.

           This will normally be /etc/ctdb/events.d which is part of the ctdb

       -i --interactive
           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.

           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.

           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

           This is the file where ctdbd will write its log. This is usually
           /var/log/log.ctdb .

           This option is used to activate the LVS capability on a CTDB node.
           Please see the LVS section.

           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.

           This file is usually /etc/ctdb/nodes .

           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.

           Please see the "remote cluster nodes" section for more information.

           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.

           Please see the "remote cluster nodes" section for more information.

           This is a ctdbd debugging option. this option is only used when
           debugging ctdbd.

           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.

           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 dont want to attach valgrind or gdb to a real-time process.)

           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.

           This file is usually /etc/ctdb/ .

           See the NOTIFICATION SCRIPT section below for more information.

           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.

           This is usually the file /etc/ctdb/public_addresses

           This option tells ctdb which interface to attach public-addresses
           to and also where to attach the single-public-ip when used.

           This is only required when using public ip addresses and only when
           you dont specify the interface explicitly in
           /etc/ctdb/public_addresses or when you are using

           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.

           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.

           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

           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.

           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

           This makes the ctdb daemon to be DISABLED when it starts up.

           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.

           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.

           A node that is DISABLED will not host any services and will not be
           reachable/used by any clients.

           This makes the ctdb daemon to be STOPPED when it starts up.

           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.

           To restart and activate a STOPPED node, the command "ctdb continue"
           is used.

           A node that is STOPPED will not host any services and will not be
           reachable/used by any clients.

           Send all log messages to syslog instead of to the ctdb logfile.

           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.

           You do NOT want to use this option unless you are developing and
           testing new functionality in ctdbd.

           This option specifies which transport to use for ctdbd internode
           communications. The default is "tcp".

           Currently only "tcp" is supported but "infiniband" might be
           implemented in the future.

           Print useage information to the screen.


       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.

   Private address
       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.

       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.

       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.

       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.

             Example /etc/ctdb/nodes for a four node cluster:


   Public address
       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.

       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.

       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.

       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.

             Example /etc/ctdb/public_addresses for a node that can host 4
       public addresses:


       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.

            Example: 4 nodes partitioned into two subgroups :

                Node 0:/etc/ctdb/public_addresses

                Node 1:/etc/ctdb/public_addresses

                Node 2:/etc/ctdb/public_addresses

                Node 3:/etc/ctdb/public_addresses

       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

       Ip address 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 also
       becomes unavailable. 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.


       The current status of each node in the cluster can be viewed by the
       ´ctdb status´ command.

       There are five possible states for a node.

       OK - This node is fully functional.

       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.

       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.

       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.

       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.

       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


       These are the public tuneables that can be used to control how ctdb

       Default: 1

       How often should the nodes send keepalives to eachother.

       Default: 5

       After how many keepalive intervals without any traffic should a node
       wait until marking the peer as DISCONNECTED.

       Default: 15

       How often should ctdb run the event scripts to check for a nodes

       Default: 20

       How often will ctdb record and store the "tickle" information used to
       kickstart stalled tcp connections after a recovery.

       Default: 20

       How long should ctdb let an event script run before aborting it and
       marking the node unhealthy.

       Default: 300

       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. Dont set to small. A node gets banned
       for a reason and it is usually due to real problems with the node.

       Default: 100000

       Size of the hash chains for the local store of the tdbs that ctdb

       Default: 10

       Once a recovery has completed, no additional recoveries are permitted
       until this timeout has expired.

       Default: 1

       When set to 0, this disables BANNING completely in the cluster and thus
       nodes can not get banned, even it they break. Dont set to 0.

       Default: 1

       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.

       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.

       Default: 0

       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´.

       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.

       Default: 0

       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.

       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.

       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.


       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.

       This is similar to using a layer-4 loadbalancing switch but with some

       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.

       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.

       The path used for a client i/o is thus :

                (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.

       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.

       Note: you can use LVS and public addresses at the same time.

       To activate LVS on a CTDB node you must specify CTDB_PUBLIC_INTERFACE
       and CTDB_LVS_PUBLIC_ADDRESS in /etc/sysconfig/ctdb.

       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.



       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

       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.


       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.

       See the cluster as one single multihomed samba server where one of the
       NICs (the remote node) is very far away.

       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.

       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:


       Verify with the command "ctdb getcapabilities" that that node no longer
       has the recmaster or the lmaster capabilities.


       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.

       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.

       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.

       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.

       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.

       There can be multiple NATGW groups in one cluster but each node can
       only be member of one NATGW group.

       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.

       NAT-GW is configured in /etc/sysconfigctdb by setting the following

           # 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=
           # CTDB_NATGW_PUBLIC_IFACE=eth0
           # CTDB_NATGW_NODES=/etc/ctdb/natgw_nodes

       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.

       Format of this parameter is IPADDRESS/NETMASK

       This is the physical interface where the CTDB_NATGW_PUBLIC_IP will be
       assigned to. This should be an interface connected to the public

       Format of this parameter is INTERFACE

       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

       Format of this parameter is IPADDRESS

       This is the network/netmask used for the interal private network.

       Format of this parameter is IPADDRESS/NETMASK

       This is the list of all nodes that belong to the same NATGW group as
       this node. The default is /etc/ctdb/natgw_nodes.

       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.

       The NAT-GW node is assigned the CTDB_NATGW_PUBLIC_IP to the designated
       interface and the provided default route. 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

       All other nodes in the group are configured with a default route of
       metric 10 pointing to the designated NAT GW node.

       This is implemented in the 11.natgw eventscript. Please see the
       eventscript for further information.

   Removing/Changing NATGW at runtime
       The following are the procedures to change/remove a NATGW configuration
       at runtime, without having to restart ctdbd.

       If you want to remove NATGW completely from a node, use these steps:

           1, Run ´CTDB_BASE=/etc/ctdb /etc/ctdb/events.d/11.natgw removenatgw´
           2, Then remove the configuration from /etc/sysconfig/ctdb

       If you want to change the NATGW configuration on a node :

           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´


       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.

       This is activated by setting CTDB_NOTIFY_SCRIPT=<your script> in the
       sysconfig file, or by adding --notification-script=<your script>.

       See /etc/ctdb/ for an example script.

       CTDB currently generates notifications on these state changes:

       This call-out is triggered when the node changes to UNHEALTHY state.

       This call-out is triggered when the node changes to HEALTHY state.

       This call-out is triggered when ctdb has started up and all managed
       services are up and running.


       CTDB has support to manage the popular anti-virus daemon ClamAV. This
       support is implemented through the eventscript :

       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.

       First, to activate CLAMAV support in CTDB, edit /etc/sysconfig/ctdb and
       add the two lines :


       Second, activate the eventscript

           ctdb enablescript 31.clamd

       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 :

           chkconfig clamd off

       Once you have restarted CTDBD, use

           ctdb scriptstatus

       and verify that the 31.clamd eventscript is listed and that it was
       executed successfully.


       ctdb(1), onnode(1)


           Copyright (C) Andrew Tridgell 2007
           Copyright (C) Ronnie sahlberg 2007

           This program is free software; you can redistribute it and/or modify
           it under the terms of the GNU General Public License as published by
           the Free Software Foundation; either version 3 of the License, or (at
           your option) any later version.

           This program is distributed in the hope that it will be useful, but
           WITHOUT ANY WARRANTY; without even the implied warranty of
           General Public License for more details.

           You should have received a copy of the GNU General Public License
           along with this program; if not, see