11. Glossary

GC

Abbreviation for garbage collection

Java heap

Area in which the Java VM allocates memory according to a memory acquisition request from a Java application. Target of GC

Java memory pool

Memory area prepared by the Java VM for Java applications

JMX

Abbreviation for Java Management Extensions. Specification used for Java that manages and monitors the hardware and software in the network

JVM operation log

File for recording JVM monitor resource operation information. The file is created in the following location:

<EXPRESSCLUSTER_install_path>/log/ha/jra/ jragent*.log

(* indicates a number starting at 0.)

JVM statistics log

File for recording statistics obtained from JVM monitor resource. The file is created in the following location:

<EXPRESSCLUSTER_install_path>/log/ha/jra/*.stat

JVM load balancer linkage log

File for recording the load balancer linkage operation information obtained from JVM monitor resource. The file is created in the following location:

<EXPRESSCLUSTER_install_path>/log/ha/jra/lbadmin.log

Interconnect

A dedicated communication path for server-to-server communication in a cluster.

(Related terms: Private LAN, Public LAN)

Virtual IP address

IP address used to configure a remote cluster.

Management client

Any machine that uses the Cluster WebUI to access and manage a cluster system.

Startup attribute

A failover group attribute that determines whether a failover group should be started up automatically or manually when a cluster is started.

Shared disk

A disk that multiple servers can access.

Shared disk type cluster

A cluster system that uses one or more shared disks.

Switchable partition

A disk partition connected to multiple computers and is switchable among computers.

(Related terms: Disk heartbeat partition)

Cluster system

Multiple computers are connected via a LAN (or other network) and behave as if it were a single system.

Cluster shutdown

To shut down an entire cluster system (all servers that configure a cluster system).

Cluster partition

A partition on a mirror disk or a hybrid disk. Used for managing mirror disks or hybrid disks.

(Related term: Disk heartbeat partition)

Active server

A server that is running for an application set.

(Related term: Standby server)

Secondary server

A destination server where a failover group fails over to during normal operations.

(Related term: Primary server)

Standby server

A server that is not an active server.

(Related term: Active server)

Disk heartbeat partition

A partition used for heartbeat communication in a shared disk type cluster.

Data partition

A local disk that can be used as a shared disk for switchable partition. Data partition for mirror disks or hybrid disks.

(Related term: Cluster partition)

Network partition

All heartbeat is lost and the network between servers is partitioned.

(Related terms: Interconnect, Heartbeat)

Node

A server that is part of a cluster in a cluster system. In networking terminology, it refers to devices, including computers and routers, that can transmit, receive, or process signals.

Heartbeat

Signals that servers in a cluster send to each other to detect a failure in a cluster.

(Related terms: Interconnect, Network partition)

Public LAN

A communication channel between clients and servers.

(Related terms: Interconnect, Private LAN)

Failover

The process of a standby server taking over the group of resources that the active server previously was handling due to error detection.

Failback

A process of returning an application back to an active server after an application fails over to another server.

Failover group

A group of cluster resources and attributes required to execute an application.

Moving failover group

Moving an application from an active server to a standby server by a user.

Failover policy

A priority list of servers that a group can fail over to.

Private LAN

LAN in which only servers configured in a clustered system are connected.

(Related terms: Interconnect, Public LAN)

Primary (server)

A server that is the main server for a failover group.

(Related term: Secondary server)

Floating IP address

Clients can transparently switch one server from another when a failover occurs.

Any unassigned IP address that has the same network address that a cluster server belongs to can be used as a floating address.

Master server

Server displayed on top of the Master Server in Server Common Properties in the Cluster WebUI

Mirror disk connect

LAN used for data mirroring in mirror disk or hybrid disk. Mirror connect can be used with primary interconnect.

Mirror disk type cluster

A cluster system that does not use a shared disk. Local disks of the servers are mirrored.