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CTDBD(1)		 CTDB - clustered TDB database		      CTDBD(1)

NAME
       ctdbd - The CTDB cluster daemon

SYNOPSIS
       ctdbd

       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] [--log-ringbuf-size=<num-entries>] [--torture]
	     [--transport=<STRING>] [--usage]

DESCRIPTION
       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.

OPTIONS
       -? --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.

       --dbdir=<directory>
	   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 .

       --dbdir-persistent=<directory>
	   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.

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

       --event-script-dir=<directory>
	   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
	   distribution.

       -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.

       --listen=<address>
	   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
	   interface.

       --logfile=<filename>
	   This is the file where ctdbd will write its log. This is usually
	   /var/log/log.ctdb .

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

       --nlist=<filename>
	   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 .

       --no-lmaster
	   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.

       --no-recmaster
	   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.

       --nosetsched
	   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 don´t want to attach valgrind or gdb to a real-time process.)

       --notification-script=<filename>
	   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/notify.sh .

	   See the NOTIFICATION SCRIPT section below for more information.

       --public_addresses=<filename>
	   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

       --public-interface=<interface>
	   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 don´t specify the interface explicitly in
	   /etc/ctdb/public_addresses or when you are using
	   --single-public-ip.

	   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.

       --reclock=<filename>
	   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
	   discouraged.

       --socket=<filename>
	   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
	   host.

       --start-as-disabled
	   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.

       --start-as-stopped
	   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.

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

       --log-ringbuf-size=<num-entries>
	   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).

	   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.

	   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.

	   Use the "ctdb getlog" command to access this log.

       --torture
	   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.

       --transport=<STRING>
	   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.

       --usage
	   Print useage information to the screen.

PRIVATE VS PUBLIC ADDRESSES
       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:

		   10.1.1.1
		   10.1.1.2
		   10.1.1.3
		   10.1.1.4

   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:

		   11.1.1.1/24 eth0
		   11.1.1.2/24 eth0
		   11.1.2.1/24 eth1
		   11.1.2.2/24 eth1

       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
		     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

       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.

       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.

NODE STATUS
       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
       it.

PUBLIC TUNABLES
       These are the public tuneables that can be used to control how ctdb
       behaves.

   MaxRedirectCount
       Default: 3

       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.

       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.

   SeqnumInterval
       Default: 1000

       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.

       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.

   ControlTimeout
       Default: 60

       This is the default setting for timeout for when sending a control
       message to either the local or a remote ctdb daemon.

   TraverseTimeout
       Default: 20

       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.

   KeepaliveInterval
       Default: 5

       How often in seconds should the nodes send keepalives to eachother.

   KeepaliveLimit
       Default: 5

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

       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.

   RecoverTimeout
       Default: 20

       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.

   RecoverInterval
       Default: 1

       How frequently in seconds should the recovery daemon perform the
       consistency checks that determine if we need to perform a recovery or
       not.

   ElectionTimeout
       Default: 3

       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.

   TakeoverTimeout
       Default: 9

       This is how many seconds we allow controls to take for IP failover
       events.

   MonitorInterval
       Default: 15

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

   TickleUpdateInterval
       Default: 20

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

   EventScriptTimeout
       Default: 20

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

   EventScriptTimeoutCount
       Default: 1

       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.

   EventScriptUnhealthyOnTimeout
       Default: 0

       This setting can be be used to make ctdb never become UNHEALTHY if your
       eventscripts keep hanging/timing out.

   RecoveryGracePeriod
       Default: 120

       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.

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

   DatabaseHashSize
       Default: 100001

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

   DatabaseMaxDead
       Default: 5

       How many dead records per hashchain in the TDB database do we allow
       before the freelist needs to be processed.

   RerecoveryTimeout
       Default: 10

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

   EnableBans
       Default: 1

       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.

   DeterministicIPs
       Default: 0

       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.

   LCP2PublicIPs
       Default: 1

       When enabled this switches ctdb to use the LCP2 ip allocation
       algorithm.

   ReclockPingPeriod
       Default: x

       Obsolete

   NoIPFailback
       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.

   DisableIPFailover
       Default: 0

       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.

       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.

   NoIPTakeover
       Default: 0

       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.

   NoIPTakeoverOnDisabled
       Default: 0

       If no nodes are healthy then by default ctdb will happily host public
       IPs on disabled (unhealthy or administratively disabled) nodes. This
       can cause problems, for example if the underlying cluster filesystem is
       not mounted. When set to 1 this behaviour is switched off and disabled
       nodes will not be able to takeover IPs.

   DBRecordCountWarn
       Default: 100000

       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.

   DBRecordSizeWarn
       Default: 10000000

       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.

   DBSizeWarn
       Default: 1000000000

       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.

   VerboseMemoryNames
       Default: 0

       This feature consumes additional memory. when used the talloc library
       will create more verbose names for all talloc allocated objects.

   RecdPingTimeout
       Default: 60

       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.

   RecdFailCount
       Default: 10

       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.

   LogLatencyMs
       Default: 0

       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".

   RecLockLatencyMs
       Default: 1000

       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.

   RecoveryDropAllIPs
       Default: 120

       If we have been stuck in recovery, or stopped, or banned, mode for this
       many seconds we will force drop all held public addresses.

   verifyRecoveryLock
       Default: 1

       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.

   DeferredAttachTO
       Default: 120

       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.

       This timeout controls how long we will defer the request from the
       client before timing it out and returning an error to the client.

   HopcountMakeSticky
       Default: 50

       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.

       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.

   StickyDuration
       Default: 600

       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.

   StickyPindown
       Default: 200

       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.

   MaxLACount
       Default: 20

       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.

   StatHistoryInterval
       Default: 1

       Granularity of the statistics collected in the statistics history.

   AllowClientDBAttach
       Default: 1

       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.

   RecoverPDBBySeqNum
       Default: 0

       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.

       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.

   FetchCollapse
       Default: 1

       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.

       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.

       This timeout controls if we should collapse multiple fetch operations
       of the same record into a single request and defer all duplicates or
       not.

   DeadlockTimeout
       Default: 60

       Number of seconds to determine if ctdb is in deadlock with samba.

       When ctdb daemon is blocked waiting for a lock on a database which is
       blocked by some other process, ctdb logs a warning every 10 seconds.
       Most often this is caused by samba locking databases and waiting on
       ctdb and result in a deadlock. If the lock is not obtained by ctdb
       before deadlock timeout expires, ctdb will detect it as a deadlock and
       terminate the blocking samba process. Setting this value to 0 disables
       deadlock detection.

   Samba3AvoidDeadlock
       Default: 0

       Enable code that prevents deadlocks with Samba (only for Samba 3.x).

       This should be set to 1 when using Samba version 3.x to enable special
       code in CTDB to avoid deadlock with Samba version 3.x. This code is not
       required for Samba version 4.x and must not be enabled for Samba 4.x.

LVS
       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
       restrictions.

       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.

   Configuration
       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
       activate LVS as a capability of the node. This should be done
       automatically for you by the /etc/init.d/ctdb script.

       Example:

		CTDB_PUBLIC_INTERFACE=eth0
		CTDB_LVS_PUBLIC_IP=10.0.0.237

       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)

       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.

REMOTE CLUSTER NODES
       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:

	   CTDB_CAPABILITY_LMASTER=no
	   CTDB_CAPABILITY_RECMASTER=no

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

NAT-GW
       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.

   NAT-GW
       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.

   Configuration
       NAT-GW is configured in /etc/sysconfig/ctdb by setting the following
       variables:

	   # 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

   CTDB_NATGW_PUBLIC_IP
       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

   CTDB_NATGW_PUBLIC_IFACE
       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.

       Format of this parameter is INTERFACE

   CTDB_NATGW_DEFAULT_GATEWAY
       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.

       Format of this parameter is IPADDRESS

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

       Format of this parameter is IPADDRESS/NETMASK

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

   Operation
       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 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).

       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´

POLICY ROUTING
       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.

   Configuration variables
       There are 4 configuration variables related to policy routing:

       CTDB_PER_IP_ROUTING_CONF
	   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 /etc/ctdb/policy_routing.

	   The special value __auto_link_local__ indicates that no
	   configuration file is provided and that CTDB should generate
	   reasonable link-local routes for each public address.

       CTDB_PER_IP_ROUTING_RULE_PREF
	   This sets the priority (or preference) for the routing rules that
	   are added by CTDB.

	   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.

       CTDB_PER_IP_ROUTING_TABLE_ID_LOW, CTDB_PER_IP_ROUTING_TABLE_ID_HIGH
	   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.

	   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.

	   CTDB uses the standard file /etc/iproute2/rt_tables 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).

   Configuration file
       The format of each line is:

	       <public_address> <network> [ <gateway> ]

       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.

       A line without a gateway indicates a link local route.

       For example, consider the configuration line:

	     192.168.1.99 192.168.1.1/24

       If the corresponding public_addresses line is:

	     192.168.1.99/24	 eth2,eth3

       CTDB_PER_IP_ROUTING_RULE_PREF is 100, and CTDB adds the address to eth2
       then the following routing information is added:

	     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

       This causes traffic from 192.168.1.1 to 192.168.1.0/24 go via eth2.

       The ip rule command will show (something like - depending on other
       public addresses and other routes on the system):

	     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

       ip route show table ctdb.192.168.1.99 will show:

	     192.168.1.0/24 dev eth2 scope link

       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:

	     192.168.1.99 0.0.0.0/0 192.168.1.1

       In the situation described above this will cause an extra routing
       command to be executed:

	     ip route add 0.0.0.0/0 via 192.168.1.1 dev eth2 table ctdb.192.168.1.99

       With both configuration lines, ip route show table ctdb.192.168.1.99
       will show:

	     192.168.1.0/24 dev eth2 scope link
	     default via 192.168.1.1 dev eth2

   Example configuration
       Here is a more complete example configuration.

	   /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

       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.

NOTIFICATION SCRIPT
       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/notify.sh for an example script.

       CTDB currently generates notifications on these state changes:

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

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

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

CLAMAV DAEMON
       CTDB has support to manage the popular anti-virus daemon ClamAV. This
       support is implemented through the eventscript :
       /etc/ctdb/events.d/31.clamd.

   Configuration
       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 :

	   CTDB_MANAGES_CLAMD=yes
	   CTDB_CLAMD_SOCKET="/path/to/clamd.socket"

       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.

SEE ALSO
       ctdb(1), onnode(1) http://ctdb.samba.org/

COPYRIGHT/LICENSE
	   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
	   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
	   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 http://www.gnu.org/licenses/.

ctdb				  01/09/2013			      CTDBD(1)
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