Cluster related terms
Clustering
A technique to make two or more computers that are running individually act as a single machine.
Clustering software
Software for controlling clusters. It monitors disk and network resources, the software, and carries out a failover when it detects errors.
ACTIVE (server or node)
A server that carries out processing during normal operation in the failover clustering environment of an HA cluster. Also known as the primary server.
STANDBY (server or node)
A server that carries out processing when the ACTIVE server in the failover clustering environment of an HA cluster fails. Also known as the alternative or secondary server.
Failover
A function that allows the STANDBY server to take over the processing from the ACTIVE server when a failure occurs.
Failback
A function that restores operations back to the ACTIVE server when the ACTIVE server is recovered after a failover. The opposite of failover.
Node
Each of the servers that together form a cluster.
Unidirectional standby configuration
A standby configuration where one instance of HULFT operates and the STANDBY server is not involved in any processing. Also known as the ACTIVE-STANDBY configuration.
Bidirectional standby configuration
A standby configuration where multiple instances of HULFT operate and the servers are ACTIVE and STANDBY. Also known as the ACTIVE-ACTIVE configuration.
Virtual IP address
An IP address that is assigned by the clustering software in which the node switching is carried out without the user being aware. In general, specific IP addresses are assigned for each function (for example, database or www). Also known as floating IP address, relocatable IP address, or package IP address.
Virtual host name
A host name that is linked to a virtual IP address. Also known as a package name.
Heartbeat
Heartbeat is a signal that is sent between nodes at fixed intervals to check if the other node is alive.
Shared disk
A disk that can be read from and written to by multiple nodes.
Mirroring
A method where each local disk on the servers always has the same data.
Online
The state in which services are started.
Offline
The state in which services are stopped.