ctdbd — The CTDB cluster daemon
ctdbd
ctdbd {--reclock=<filename>} {--nlist=<filename>} {--dbdir=<directory>} [-? --help] [--usage] [-i --interactive] [--public-addresses=<filename>] [--event-script=<filename>] [--logfile=<filename>] [--listen=<address>] [--transport=<STRING>] [--socket=<filename>] [-d --debug=<INTEGER>] [--torture]
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-awailability load-sharing CIFS server cluster.
Print some help text to the screen.
Print useage information to the screen.
This is the name of the lock file stored of the shared cluster filesystem that ctdbd uses to arbitrate which node has the role of recovery-master. This file must be stored on shared storage.
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 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 .
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.
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 iwll distribute these public ip addresses evenly across the availabel nodes.
This is usually the file /etc/ctdb/public_addresses
This option is used to specify which events script that ctdbd will use to manage services when the cluster configuration changes.
This will normally be /etc/ctdb/events which is part of the ctdb distribution.
This is the file where ctdbd will write its log. This is usually /var/log/log.ctdb .
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.
This option specifies which transport to use for ctdbd internode communications. The default is "tcp".
Suported transports are "tcp" and "infiniband".
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.
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 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.
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.
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.
Each node is assigned an internal node number which corresponds to which line in the nodes file that has the local private address of the node.
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.
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
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. You should NOT have this address configured to an interface in linux. Let ctdbd manage these addresses.
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.
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.
The list of public addresses also contain the netmask and the interface where this address should be attached.
Example /etc/ctdb/public_addresses for a four node cluster:
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 this example, two nodes in the cluster will serve 11.1.1.1 and 11.1.1.2 through interface eth0 and two (possibly other) nodes will serve 11.1.2.1 and 11.1.2.2 through eth1.
The public address file must be the same on all nodes. Since this file also specifies which interface the address should be attached to it is imporant that all nodes use the same naming convention for interfaces.
The current status of each node in the cluster can be viewed by the 'ctdb status' command.
There are five possible 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.
Copyright (C) Andrew Tridgell 2007
Copyright (C) Ronnie sahlberg 2007
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