Neverfail Glossary

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Summary

This Knowledgebase article provides a list of terms and definitions used by Neverfail.

 

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Active
The functional state or role of a server that is visible through the network by clients, is running any protected applications, and thus servicing client requests.

Active Directory (AD)
Presents applications with a single, simplified set of interfaces so users can locate and use directory resources from a variety of networks while bypassing differences among proprietary services; Neverfail switchovers and failovers require no changes to AD resulting in switchovers/failover times typically measured in seconds.

Active – Passive
The coupling of two servers with one server visible to clients on a network and providing application service while the other server is not visible and not providing application service to clients.

Active Server Queue
The staging area of the active server used to store intercepted data changes before being transported across the channel to the passive server.

Advanced Configuration and Power Interface (ACPI)
A specification that dictates how the operating system can interact with the hardware especially where power saving schemes are used; the Primary and Secondary servers should have the same ACPI compliance.

Asynchronous
A process whereby replicated data is applied (written) to the active server independently of the passive server.

Basic Input/Output System (BIOS)
The program a personal computer's microprocessor uses to get the computer system started after you turn it on. It also manages data flow between the computer's operating system and attached devices such as the hard disk, video adapter, keyboard, mouse, and printer.

Cached Credentials
Locally stored security access credentials used to log into a computer system when a Domain Controller is not available.

Channel Drop
An event in which the dedicated communications link between the Primary and Secondary server fails, often resulting in the passive server becoming active and consequently creating a split-brain syndrome.

Channel NIC (Network Interface Card)
A dedicated subnet used by the Neverfail Channel.

Cloned Servers
A component of the Neverfail installation process that copies all installed programs, configuration settings, and the machine name, Security Identifier (SID), and IP address to a second server.

Cloning Process
The Neverfail process whereby all installed programs, configuration settings, and the machine name, security identifier (SID), and IP address are copied to a second server.

Crossover Cable
A network cable that crosses the transmit and receive lines.

Data Replication
The transmission of changed data (files and registry settings), from the active to the passive server via the Neverfail Channel.

Data Rollback
A Neverfail module that allows administrators to rollback the entire state of an application (including files and registry settings) to an earlier point-in-time; typically used after some form of data loss or corruption.

Device Drivers
A program that controls a hardware device, linking it to the operating system.

Disaster Recovery (DR)
A term indicating how you maintain and recover data in light of a disaster such as a hurricane or fire; with Neverfail, DR protection can be achieved by placing the Secondary server at on offsite facility, and replicating the data through a WAN link.

DNS (Domain Name System) Server
Responsible for providing a centralized resource for clients to resolve NetBIOS names to IP addresses.

Domain
A logical group of client server based machines where the administration of rights across the network are maintained in a centralized resource called a domain controller.

Domain Controller (DC)
The server responsible for maintaining privileges to domain resources; sometimes called AD controller in Windows 2000 and above domains.

Failover
A critical unexpected outage or crash of a server.

Full System Check (FSC)
The internal process automatically started at the initial connection of a server pair or manually triggered through the Manage Server GUI to perform verification on the files and registry keys and then synchronize the differences.

Graceful (Clean) Shutdown
A shutdown of Neverfail based upon completion of replication by use of the Neverfail Management Client GUI, resulting in no data loss.

Hardware Agnostic
A key Neverfail feature allowing for the use of servers from different manufacturers and/or models, and processing power in a single Neverfail server pair.

Heartbeat
The packet of information issued by the passive server across the channel, which the active server responds to indicating its presence.

High Availability (HA)
Keeping users seamlessly connected to their applications, regardless of the nature of a failure; LAN environments are ideally suited for HA.

Hotfix
A single, cumulative package that includes one or more files that are used to address a problem in a product.

Identity
The reference given to a server as to its position in the server pair; based upon hardware and is either the Primary server or the Secondary server.

Low Bandwidth Module (LBM)
A Neverfail Module that compresses and optimizes data replications between a Primary and Secondary server, thereby delivering maximum data throughput and improving application response time on congested WAN links.

Machine Name
Refers to the Windows or NETBIOS name of a computer.

Management IP Address
An additionally assigned unfiltered IP address used for server management purposes only .

Many-To-One
The ability of one physical Secondary server (hosting more than one virtual server) to protect multiple physical Primary servers.

microSCOPE CSV File
The file created during the SCOPE process containing the results of the system, environment, and bandwidth interrogation.

Network Monitoring
Monitoring of the active server’s ability to communicate with the rest of the network by polling defined nodes around the network at regular intervals.

Neverfail Application Modules
Installed over and above the Neverfail Heartbeat core product - responsible for the monitoring of a protected application.

Neverfail Application Module eXtension
An application that extends Neverfail protection to include third party applications such as antivirus or anti-spam.

Neverfail Channel
The IP communications link used by the Neverfail system for heartbeat and replication traffic.

Neverfail Extranet
The Neverfail web site dedicated to the support of partners and customers providing technical information, software updates, and license key generation.

Neverfail Heartbeat
The core replication and system monitoring component of all Neverfail products.

Neverfail License Key
The key obtained from the Neverfail extranet that allows the use of components in the Neverfail Suite of products; entered at install time, or through the Configure Server wizard.

Neverfail Packet Filter
The network component, installed on both servers, that controls network visibility.

Neverfail SCOPE
The umbrella name for the Neverfail process and tools used to check the production servers health and applicability to the implementation of a Neverfail solution.

Neverfail SCOPE Report
Provided upon the completion of the Neverfail SCOPE process that provides information about the server, system environment, and bandwidth.

Neverfail’s Switchover/Failover Process
A Neverfail unique process whereby the passive server gracefully (Switchover) or unexpectedly (failover) assumes the role of the active server providing application services to connected clients.

Passive
The functional state or role of a server that is not delivering service to clients and is hidden from the rest of the network.

Passive Server Queue
The staging area on the passive server used to store changes received from the active server before they are applied to the passive server’s disk/registry.

Pathping
A route-tracing tool that works by sending packets to each router on the way to a final destination and displays the results of each hop.

Plug-and-Play (PnP)
A standard for peripheral expansion on a PC; on starting the computer, Plug and Play (PnP) causes the necessary IRQ, DMA and I/O address settings for the attached peripheral devices to be configured automatically.

Pre-Installation Checks
A list of system and environmental checks performed before the installation of Neverfail’s product.

Principal IP address
An I.P. address that is used by clients to contact the server through drive mappings, UNC paths, DNS resolved paths, etc. to gain access to the server's services and resources.

Principal NIC
The network card which hosts the Principal IP address.

Protected Application
An application protected by the Neverfail solution.

Quality of Service (QoS)
An effort to provide different prioritization levels for different types of traffic over a network. For example, Neverfail data replication may have a higher priority than ICMP traffic, as the consequences of interrupting data replication are more obvious than slowing down ICMP traffic.

Remote Desktop Protocol (RDP)
A multi-channel protocol that allows a user to connect to a computer running Microsoft Terminal Services.

Replicate
The generic term given to the process of intercepting changes to data files and registry keys, transporting the changed data across the channel and applying them to the passive server so both servers are maintained in a synchronized state.

Role
The functional state of the server in the pair and can be either active or passive.

Security Identifier (SID)
A unique alphanumeric character string that identifies each operating system and each user in a network of NT/2000/2003 systems.

Server Monitoring
Monitoring of the active server by the passive server, using a heartbeat message, to ensure that the active server is functional.

Server Pair
The generic term used to describe the coupling of the Primary and Secondary server in a Neverfail Solution.

Shared Nothing
A key Neverfail feature whereby hardware is not shared between the Primary and Secondary servers, thus preventing a single point of failure.

SMTP
A TCP/IP protocol used in sending and receiving e-mail between or among servers.

Split-Brain Avoidance
A unique feature of the Neverfail product that uses various checks to overcome a scenario where both Primary and Secondary servers attempt to become active at the same time leading to an active-active rather than and active-passive model.

Split-brain Syndrome
A situation where both the Primary and Secondary servers in a Neverfail server pair are operating in the active mode and attempting to service clients, causing different data updates to be applied independently to each server.

Subnet
A division of a network into an interconnected, but independent, segment, or domain, in order to improve performance and security.

Storage Area Network (SAN)
A high-speed special-purpose network or (subnetwork) that interconnects different kinds of data storage devices with associated data servers on behalf of a larger network of users.

Switchover
The graceful transfer of control and application service to the passive server.

Synchronize
The internal process of transporting 64KB blocks of changed files or registry key data, through the Neverfail channel, from the active server to the passive server; ensures the data on the passive server is a mirror image of the protected data on the active server; a required condition for data replication on a Neverfail server pair.

System State
Data that comprises the registry, COM+ Class Registration database, files under Windows File Protection, and system boot file; other data may be included in the system state data.

Time-To-Live (TTL)
The length of time that a locally cached DNS resolution is valid; the DNS server must be re-queried after the TTL expires.

Traceroute
A utility that records the route through the Internet between your computer and a specified destination computer.

Ungraceful (Unclean) Shutdown
A shutdown of Neverfail resulting from a critical failure or by shutting down Windows without first performing a proper shutdown of Neverfail Heartbeat, resulting in possible data loss.

Unprotected Application
An application that is not monitored or replicated by Neverfail.

Virtual Private Network (VPN)
A private data network that makes use of the public telecommunication infrastructure, maintaining privacy through the use of a tunneling protocol and security procedures.

Windows Management Instrumentation (WMI)
A management technology allowing scripts to monitor and control managed resources throughout the network. Resources include hard drives, file systems, operating system settings, processes, services, shares, registry settings, networking components, event logs, users, clusters, and groups.

 

Applies To

All Versions

 

Related Information

None

KBID-6

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