Concept
Réplication (informatique)
Concepts associés (15)
Clustered file system
A clustered file system is a which is shared by being simultaneously mounted on multiple servers. There are several approaches to clustering, most of which do not employ a clustered file system (only direct attached storage for each node). Clustered file systems can provide features like location-independent addressing and redundancy which improve reliability or reduce the complexity of the other parts of the cluster. Parallel file systems are a type of clustered file system that spread data across multiple storage nodes, usually for redundancy or performance.
Distributed lock manager
Operating systems use lock managers to organise and serialise the access to resources. A distributed lock manager (DLM) runs in every machine in a cluster, with an identical copy of a cluster-wide lock database. In this way a DLM provides software applications which are distributed across a cluster on multiple machines with a means to synchronize their accesses to shared resources. DLMs have been used as the foundation for several successful s, in which the machines in a cluster can use each other's storage via a unified , with significant advantages for performance and availability.
Serializability
In concurrency control of databases, transaction processing (transaction management), and various transactional applications (e.g., transactional memory and software transactional memory), both centralized and distributed, a transaction schedule is serializable if its outcome (e.g., the resulting database state) is equal to the outcome of its transactions executed serially, i.e. without overlapping in time. Transactions are normally executed concurrently (they overlap), since this is the most efficient way.
Base de données distribuée
thumb|Schéma d'un exemple de base de données distribuée En informatique, une base de données distribuée ou BDD (en anglais : distributed database) est une base de données dont la gestion est traitée par un réseau d'ordinateurs interconnectés qui stockent des données de manière distribuée. Ce stockage peut être soit partitionné entre différents nœuds du réseau, soit répliqué entièrement sur chacun d'eux, ou soit organisé de façon hybride. Théorème CAP Blockchain Catégorie:Base de données Catégorie:Stockage i
Optimistic replication
Optimistic replication, also known as lazy replication, is a strategy for replication, in which replicas are allowed to diverge. Traditional pessimistic replication systems try to guarantee from the beginning that all of the replicas are identical to each other, as if there was only a single copy of the data all along. Optimistic replication does away with this in favor of eventual consistency, meaning that replicas are guaranteed to converge only when the system has been quiesced for a period of time.
Disk mirroring
In data storage, disk mirroring is the replication of logical disk volumes onto separate physical hard disks in real time to ensure continuous availability. It is most commonly used in RAID 1. A mirrored volume is a complete logical representation of separate volume copies. In a disaster recovery context, mirroring data over long distance is referred to as storage replication. Depending on the technologies used, replication can be performed synchronously, asynchronously, semi-synchronously, or point-in-time.
Synchronisation (multitâches)
En programmation concurrente, la synchronisation se réfère à deux concepts distincts mais liés : la synchronisation de processus et la synchronisation de données. La synchronisation de processus est un mécanisme qui vise à bloquer l'exécution de certains processus à des points précis de leur flux d'exécution, de manière que tous les processus se rejoignent à des étapes relais données, tel que prévu par le programmeur. La synchronisation de données, elle, est un mécanisme qui vise à conserver la cohérence des données telles que vues par différents processus, dans un environnement multitâche.
Basculement (informatique)
thumb|Schéma d'un couple de serveurs permettant le basculement en cas de panne. Le basculement (en anglais, fail-over qui se traduit par passer outre à la panne) est la capacité d'un équipement à basculer automatiquement vers un réseau ou un système alternatif ou en veille. Cette capacité existe pour tout type d'équipement réseau : du serveur au routeur en passant par les pare-feux et les commutateurs réseau (switch). Le basculement intervient généralement sans action humaine et même bien souvent sans aucun message d'alerte.
Concurrency control
In information technology and computer science, especially in the fields of computer programming, operating systems, multiprocessors, and databases, concurrency control ensures that correct results for concurrent operations are generated, while getting those results as quickly as possible. Computer systems, both software and hardware, consist of modules, or components. Each component is designed to operate correctly, i.e., to obey or to meet certain consistency rules.
Database transaction
A database transaction symbolizes a unit of work, performed within a database management system (or similar system) against a database, that is treated in a coherent and reliable way independent of other transactions. A transaction generally represents any change in a database. Transactions in a database environment have two main purposes: To provide reliable units of work that allow correct recovery from failures and keep a database consistent even in cases of system failure.