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You only need to specify this parameter if you run multiple ctdb daemons on the same physical host and thus can not use the default name for the domain socket.
DISCONNECTED \- This node could not be connected through the network and is currently not participating 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 currnetly 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.
The generation id is a number that indicates the current generation of a cluster instance. Each time a cluster goes through a reconfiguration or a recovery its generation id will be changed.
This number does not have any particular meaning other than to keep track of when a cluster has gone through a recovery. It is a random number that represents the current instance of a ctdb cluster and its databases. CTDBD uses this number internally to be able to tell when commands to operate on the cluster and the databases was issued in a different generation of the cluster, to ensure that commands that operate on the databases will not survive across a cluster database recovery. After a recovery, all old outstanding commands will automatically become invalid.
Sometimes this number will be shown as "INVALID". This only means that the ctdbd daemon has started but it has not yet merged with the cluster through a recovery. All nodes start with generation "INVALID" and are not assigned a real generation id until they have successfully been merged with a cluster through a recovery.
The list of Virtual Node Numbers. This is a list of all nodes that actively participates in the cluster and that share the workload of hosting the Clustered TDB database records. Only nodes that are participating in the vnnmap can become lmaster or dmaster for a database record.
RECOVERY \- The cluster databases have all been frozen, pausing all services while the cluster awaits a recovery process to complete. A recovery process should finish within seconds. If a cluster is stuck in the RECOVERY state this would indicate a cluster malfunction which needs to be investigated.
Once the recovery master detects an inconsistency, for example a node becomes disconnected/connected, the recovery daemon will trigger a cluster recovery process, where all databases are remerged across the cluster. When this process starts, the recovery master will first "freeze" all databases to prevent applications such as samba from accessing the databases and it will also mark the recovery mode as RECOVERY.
When CTDBD starts up, it will start in RECOVERY mode. Once the node has been merged into a cluster and all databases have been recovered, the node mode will change into NORMAL mode and the databases will be "thawed", allowing samba to access the databases again.
This is the cluster node that is currently designated as the recovery master. This node is responsible of monitoring the consistency of the cluster and to perform the actual recovery process when reqired.
Only one node at a time can be the designated recovery master. Which node is designated the recovery master is decided by an election process in the recovery daemons running on each node.
Get the current debug level for the node. the debug level controls what information is written to the log file.
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The debug levels are mapped to the corresponding syslog levels. When a debug level is set, only those messages at that level and higher levels will be printed.
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The list of debug levels from highest to lowest are :
This command is used to administratively disable a node in the cluster. A disabled node will still participate in the cluster and host clustered TDB records but its public ip address has been taken over by a different node and it no longer hosts any services.
A banned node does not participate in the cluster and does not host any records for the clustered TDB. Its ip address has been taken over by an other node and no services are hosted.
This command can be used to manually fail a public ip address to a specific node.
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In order to manually override the "automatic" distribution of public ip addresses that ctdb normally provides, this command only works when you have changed the tunables for the daemon to:
This command is used to unban a node that has either been administratively banned using the ban command or has been automatically banned by the recovery daemon.
This command is used when adding new nodes to an existing cluster and to reduce the disruption of this operation. This command should never be used except when expanding an existing cluster. This can only be used to expand a cluster. To remove a node from the cluster you still need to shut down ctdb on all nodes, edit the nodes file and restart ctdb.
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Procedure:
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1, To expand an existing cluster, first ensure with 'ctdb status' that all nodes are up and running and that they are all healthy. Do not try to expand a cluster unless it is completely healthy!
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2, On all nodes, edit /etc/ctdb/nodes and add the new node as the last entry to the file. The new node MUST be added to the end of this file!
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3, Verify that all the nodes have identical /etc/ctdb/nodes files after you edited them and added the new node!
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4, Run 'ctdb reloadnodes' to force all nodes to reaload the nodesfile.
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5, Use 'ctdb status' on all nodes and verify that they now show the additional node.
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6, Install and configure the new node and bring it online.
This command will will send a TCP tickle to the source host for the specified TCP connection. A TCP tickle is a TCP ACK packet with an invalid sequence and acknowledge number and will when received by the source host result in it sending an immediate correct ACK back to the other end.
TCP tickles are useful to "tickle" clients after a IP failover has occured since this will make the client immediately recognize the TCP connection has been disrupted and that the client will need to reestablish. This greatly speeds up the time it takes for a client to detect and reestablish after an IP failover in the ctdb cluster.
Over time, when records are created and deleted in a TDB, the TDB list of free space will become fragmented. This can lead to a slowdown in accessing TDB records. This command is used to defragment a TDB database and pruning the freelist.
During repacking of the database, the entire TDB database will be locked to prevent writes. If samba tries to write to a record in the database during a repack operation, samba will block until the repacking has completed.
This command can be disruptive and can cause samba to block for the duration of the repack operation. In general, a repack operation will take less than one second to complete.
A repack operation will only defragment the local TDB copy of the CTDB database. You need to run this command on all of the nodes to repack a CTDB database completely.
Over time CTDB databases will fill up with empty deleted records which will lead to a progressive slow down of CTDB database access. This command is used to prune all databases and delete all empty records from the cluster.
By default, vacuum will delete all empty records from all databases. If [max_records] is specified, the command will only delete the first [max_records] empty records for each database.
Vacuum only deletes records where the local node is the lmaster. To delete all records from the entire cluster you need to run a vacuum from each node. This command is not disruptive. Samba is unaffected and will still be able to read/write records normally while the database is being vacuumed.
This command checks if a specific process exists on the CTDB host. This is mainly used by Samba to check if remote instances of samba are still running or not.
This command lists all clustered TDB databases that the CTDB daemon has attached to. Some databases are flagged as PERSISTENT, this means that the database stores data persistently and the data will remain across reboots. One example of such a database is secrets.tdb where information about how the cluster was joined to the domain is stored.
Most databases are not persistent and only store the state information that the currently running samba daemons need. These databases are always wiped when ctdb/samba starts and when a node is rebooted.
This command returns the monutoring mode of a node. The monitoring mode is either ACTIVE or DISABLED. Normally a node will continously monitor that all other nodes that are expected are in fact connected and that they respond to commands.
ACTIVE \- This is the normal mode. The node is actively monitoring all other nodes, both that the transport is connected and also that the node responds to commands. If a node becomes unavailable, it will be marked as DISCONNECTED and a recovery is initiated to restore the cluster.
DISABLED \- This node is not monitoring that other nodes are available. In this mode a node failure will not be detected and no recovery will be performed. This mode is useful when for debugging purposes one wants to attach GDB to a ctdb process but wants to prevent the rest of the cluster from marking this node as DISCONNECTED and do a recovery.
This command can be used to explicitely disable/enable monitoring mode on a node. The main purpose is if one wants to attach GDB to a running ctdb daemon but wants to prevent the other nodes from marking it as DISCONNECTED and issuing a recovery. To do this, set monitoring mode to 0 on all nodes before attaching with GDB. Remember to set monitoring mode back to 1 afterwards.
This command will lock all the local TDB databases causing clients that are accessing these TDBs such as samba3 to block until the databases are thawed.
