Systems or applications requiring a very high level of reliability and availability. High availability systems typically operate 24x7 and usually require built-in redundancy to minimize the risk of downtime due to hardware and/or telecommunication failures.
A configuration that enables two Solaris servers to run a single instance of Calendar Server 5.1 that remains continuously available after any single point of failure in hardware (disk, server, or network) or software has occurred in either of the servers.
The ability of a system or network to be accessible almost all of the time, through additive or built-in mechanisms that make the resource tolerant of failures. The most common implementation to achieve high availability is to provide a hot failure-over mechanism. This ensures that, in the case of failure, a standby system would take over operation. When talking about high availability systems, the measurement of the capabilities is the switch-over time, and whether or not any information/connection is lost during the switch-over. High availability can be achieved using software and/or hardware.
A type of system with redundant components that provides consistent and uninterrupted service, even when hardware or software fails. Availability is often expressed as a percentage of time that the database is available over the period of a year, such as 99.95%. It can also be expressed as the number of hours times the number of days in the week that the system is expected to run, such as 24 hours a day and 7 days a week. High availability can be defined to exclude unplanned downtime only or both planned and unplanned downtime.
The ability of a system to perform its function continuously, without interruption.
A network topology feature that ensures mission critical applications are available 100% of the time, on a 24x7 basis. This goal is typically accomplished by having multiple access routers with multiple WAN link interfaces. Packeteer units can enhance a high availability topology by detecting when interfaces and routers go down and then adjusting the rate of the flows and partitions based on the status of the devices. High availability has two modes: basic and advanced.
A system type with redundant components that provides consistent and uninterrupted service, even in the event of hardware or software failures.
Real time data replication onto a secondary server or AS/400 to allow for minimal downtime. A "failover" may occur whereby operations are switched over the mirrored server, from production server.
High availability is defined as the continuous operation of systems. For a system to be available all components including application and database servers, storage devices and the end-to-end network need to provide continuous service.
A system that is designed to reduce the amount of downtime a system suffers.
A high probability that a system will be operational at any given time, and will recover quickly in the event of a failure. In general, a high-availability system has a relatively low vulnerability to unscheduled outages, such as power failures, code defects or hardware failures.
Highly available systems protect users from software failure, as well as from failure of a processing unit, a disk, a LAN component, or an interface card.
Methods of ensuring rapid recovery from hardware or software failure employing redundancy and failover to backup components.
The ability of a resource to withstand a hardware or software failure. High availability is achieved by using some form of resource duplication that removes single points of failure. Availability also is measured by a resource's reliability. No resource can be protected against an infinite number of failures.
A continuously available computer system is characterized as having essentially no downtime in any given year. A system with 99.999% availability experiences only about five minutes of downtime. In contrast, a high availability system is defined as having 99.9% uptime, which translates into a few hours of planned or unplanned downtime per year.
A method of providing continuous access to a network resource or application, such as a VPN, firewall, or web server, by configuring clusters of redundant servers. The servers are continuously synchronized to provide automatic fail over. A high availability solution enables these redundant systems to detect when the primary server is unavailable. A key component of high availability is that the switch to secondary systems should occur without the end user realizing it. For example, a VPN connection should switch over without the need to restart a session or for the user to re-authenticate.
High Availability enables the installation of two Fireboxes so that if one fails for any reason, the other takes over immediately. This minimizes data loss while the failed box is replaced or repaired..
High availability is a system design protocol and associated implementation that ensures a certain absolute degree of operational continuity during a given measurement period.