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Glossary

active/active pair configuration
This type of configuration has a complete duplicate system available with both systems actively performing (probably different) services during normal operations. When a resource on one system fails, local recovery is attempted by LifeKeeper on that system; if it fails, inter-server recovery is attempted.
active/standby pair configuration
This type of configuration consists of a primary server that handles processing and a backup server that stands by in case of a failure on the primary server.
alive
The state of the system. The system is believed to be available.
applet
A program which runs in a Java-enabled browser.
asynchronous mirroring
In asynchronous mirroring, the primary system makes the local writes first and then queues a copy of that write to be transmitted to the backup system.
backup system
This is a synonym for alternate system, spare system or secondary system.
browser
See web browser.
cascading failover
See cascading recovery.
client/server
An application architecture where the application is broken down into individual components that are distributed on a network of computers.
communication path
A periodic message between servers in a LifeKeeper cluster. The communication path can be either LAN-based (TCP) or TTY.
command line interface
See LifeKeeper Configuration Database Interface Commands (LCDI).
Database Management System (DBMS)
Commercial products that provide relational database management including data storage, retrieval and update, transaction control, concurrency control, recovery and backup services and relational data integrity.
dependency
Resources frequently require the availability of other resources to function properly. For example, a file system resource would require a device resource to work properly. When a resource requires another resource, it is called a dependency. The resource requiring the other resource is called the dependent.
differential SCSI
A version of the SCSI bus that is designed for longer cable lengths (up to 25 meters) and has improved resistance to noise. It is not compatible with the single-ended version of the SCSI bus.
error reporting software
Software that monitors a resource for errors and reports them through the sendevent program.
fault tolerant
Class of systems using special hardware and software such that they are completely tolerant of any single fault providing continuous processing and complete data integrity.
fence level
The method of determining the behavior of a mirror in a failure scenario.
function keys
Keys that request actions but do not display or print characters. Included are the keys that normally produce a printed character, but when used with the code key produce a function instead.
heartbeat
A periodic message between each pair of servers in a group; a key fault detection facility in LifeKeeper. The heartbeat is also called a communication path or comm path.
high reliability
A system that has fewer failures as compared to a normal system.
ILLSTATE
A state that a resource instance can be in. A resource in this state has not been initialized properly by the resource initialization process which is run as part of the startup sequence of LifeKeeper. Resources in this state are not under LifeKeeper protection.
In-Service, Protected (ISP)
A state a resource instance can be in. A resource in this state is"in-service" and LifeKeeper has local recovery protection turned ON.
instance ID
See resource ID.
instances file
A file containing information on resource instances that is used for permanent storage of such information.
Intelligent Switchback
Once the failover occurs for that resource from Server A to Server B, the resource remains on Server B until another failure or until an administrator intelligently switches the resource to another server. The alternative is Automatic switchback.
ISU
See In-Service, Unprotected.
Java Native Interface
Allows Java code within a Java Virtual Machine to inter-operate with applications and libraries written in other programming languages such as C and C++.
LAI
See LifeKeeper Alarming Interface.
LCDI
See LifeKeeper Configuration Database Interface.
LCMI
See LifeKeeper Communications Manager Interface.
LifeKeeper Communications Manager (LCM)
The LCM may be used by the Application Recovery Kits to obtain status and descriptive information about resource instances on other systems. It is also used to detect system failure and start failover recovery.
LifeKeeper Configuration Database (LCD)
Keeps track of local and remote system resources and their interrelationships.
LifeKeeper Data Replication (SteelEye DataKeeper)
This software provides integrated synchronous data mirroring that allows LifeKeeper resources to operate in a non-shared storage environment.
LifeKeeper Core Software
The set of software that provides the basic functionality of LifeKeeper. It includes the LCD, LA and LCM components. The LifeKeeper interface software LAI, LRACI, LCMI and LCDI is also included. Without these packages, LifeKeeper does not have the capability to recover any resources. Note that the core software does not include the Application Recovery Kits.
LKROOT
LKROOT describes where the LifeKeeper software resides on the system. It is defined in the file /etc/default/LifeKeeper. By default, LKROOT is defined to be /opt/LifeKeeper.
lock
See reserve.
LRACI
See LifeKeeper Recovery and Control Interface.
mailbox
A software entity used by the LCM and LifeKeeper software to communicate between processes and systems.
mirror
A mirror is a disk partition on a primary server whose contents are synchronized across a network to a corresponding disk partition on a backup server. Mirroring capability is provided by SteelEye DataKeeper software.
multihost
An environment where two or more hosts are configured to share the same SCSI bus. The host adapters on different hosts have access to all SCSI devices configured on the shared bus.
N-way recovery
N-way recovery allows different resources to fail over to different backup servers in a cluster. For instance, one application might fail over to Server B, while a different application might fail over to Server C.
Network Block Device (NBD)
A device driver extension to the Linux kernel that lets Linux use a remote server as one of its local block devices. The NetRAID device used by the SteelEye DataKeeper software is comprised of a local disk partition and a Network Block Device coupled together using the raid1 functionality of md.
OSF
See Out-of-Service, Failed.
OSU
See Out-of-Service, Unimpaired.
Out-of-Service, Unimpaired (OSU)
A state that a resource instance can be in. A resource in this state is "out-of-service" and is not available for use because it was brought out of service by executing its remove script.
pairdisplay
Displays the state of volumes.
RAID
See Redundant Array of Inexpensive Disks.
recovery actions
This software performs the basic actions that the resource recovery process may require. For example, some of the actions may be "reset diskheads" or "initialize pumpware."
recovery log
A listing of messages that LifeKeeper generates when a resource makes a transition between states, or informational messages generated by the Application Recovery Kit when an automatic recovery (local or failover) occurs. It also records time-stamped messages generated when communications between servers are interrupted, and messages generated during LifeKeeper initialization.
Redundant Array of Inexpensive Disks (RAID)
Software or hardware that uses multiple disks to create a virtual disk that improves data availability and data access performance by splitting and duplicating data across the set of physical disks.
Remote Method Invocation (RMI)
Designed for creating Java objects whose methods can be invoked from another virtual machine (local or over the network).
reserve
A SCSI command that allows a SCSI host adapter to gain exclusive access to an entire SCSI device.
resource hierarchy
A resource, along with its dependents, forms a hierarchy of dependencies. This is known as the resource hierarchy. Graphically, this forms a directed, acyclic graph.
resource info
A character string associated with a resource instance that gives additional information that identifies some internal characteristics of the resource instance. An example may be ufs for a file-sys resource type that indicates that the file system is a Unix UFS file system.
resource states
A resource instance can be in one of five states at any given time. See states.
resource type
A class of hardware, software or system entities providing a service (for example, application software).
RMI
See Remote Method Invocation.
SAN
See Storage Area Network
SCSI bus
An industry standard peripheral bus that is used to connect intelligent peripherals to a host computer. It uses a daisy-chained cabling arrangement that originates at the host adapter to interconnect up to six intelligent peripheral controllers on a shared bus.
SCSI device
A host computer adapter or a peripheral controller or an intelligent peripheral that can be attached to a SCSI bus.
SCSI host adapter (HA)
A SCSI initiator that issues a SCSI command to be performed by another SCSI device (a target) on the bus.
secondary system
The second highest priority system for a given resource hierarchy.
shared resource
A resource that may exist on several systems but only on one system at a time. An example would be a shared SCSI disk.
Small Computer System Interface (SCSI)
An intelligent bus-based interface for interconnecting host computers to a variety of common peripheral devices.
SNMP
See Simple Network Management Protocol
standby system
A system which is operational and is ready to take over operation of LifeKeeper resources.
Storage Area Network
A network operating with both SCSI and networking (IP) protocols which links one or more servers to one or more storage systems.
switchback
A term used to refer to the behavior of a system when it returns to an active state after a shutdown or failure. See automatic switchback and intelligent switchback.
target
A SCSI device that receives and executes a SCSI command that was issued by a SCSI host adapter.
TCP/IP
See Transport Control Protocol/Internet Protocol.
Template Server
When extending a resource hierarchy, the server on which the existing hierarchy currently resides is referred to as the template server.
transport layer program
A library of functions that defines how an application accesses the services of a transport provider; based on the Transport Service Definition (Level 4) of the International Standards Organization (ISO) Open Systems Interconnection (OSI) reference model.
Uniform Resource Locator
A standard for specifying an object on the internet such as a file or newsgroup. URLs look like http://www.xyz.com/foo.html, where the part before the colon identifies the access method, and the // indicates a machine name or port.
URL
See Uniform Resource Locator.
web browser
A program which reads documents and fetches documents from other sources/servers. Web browsers can display text, images, sound, animation, etc.
www
See world wide web.

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