Replication is one of the oldest and most important topics in the overall area of distributed systems.ĭata replication and computation replication both require processes to handle incoming events. Replicas, on the other hand, undergo frequent updates and quickly lose any historical state. Load balancing, however, sometimes uses data replication (especially multi-master replication) internally, to distribute its data among machines.īackup differs from replication in that the saved copy of data remains unchanged for a long period of time. Load balancing differs from task replication, since it distributes a load of different computations across machines, and allows a single computation to be dropped in case of failure. In the latter case, some form of distributed concurrency control must be used, such as a distributed lock manager. In comparison, if any replica can process a request and distribute a new state, the system is using a multi-primary or multi-master scheme. When one leader replica is designated via leader election to process all the requests, the system is using a primary-backup or primary-replica scheme, which is predominant in high-availability clusters. Passive replication, which involves processing every request on a single replica and transferring the result to the other replicas.Active replication, which is performed by processing the same request at every replica.Ĭomputer scientists further describe replication as being either: In a failure scenario, a failover of replicas should be hidden as much as possible with respect to quality of service. The replication itself should be transparent to an external user. Īccess to a replicated entity is typically uniform with access to a single non-replicated entity. Replication in space or in time is often linked to scheduling algorithms. Replicated in time, where tasks are executed repeatedly on a single device.Replicated in space, where tasks are executed on separate devices.Computation replication, where the same computing task is executed many times.Data replication, where the same data is stored on multiple storage devices.Replication in computing involves sharing information so as to ensure consistency between redundant resources, such as software or hardware components, to improve reliability, fault-tolerance, or accessibility.

( October 2012) ( Learn how and when to remove this template message) Please help to improve this article by introducing more precise citations. This article includes a list of general references, but it lacks sufficient corresponding inline citations.

Download SQL Backup Master 6.3.628.0