Database Mirroring in SQL Server 2008 R2
Database mirroring is a primarily software solution for increasing database availability. Mirroring is implemented on a per-database ...
High Availability (HA) Database
Keep your businness up and running. Increase the service availability and data safety. Automatic failover with zero downtime.
High Availability Database Description
High Availability in a database refers to maintaining levels of uptime that exceed normal service level agreements. High availability databases achieve such uptime by eliminating single points of failure, reliably failing over to a redundant node, and monitoring for failures to initiate failover when needed. In practice, a high availability database is designed to run with no interruptions in service, even in the event of network latency and hardware outages.
High Availability Database Solution
HA database implementation for popluar database management systems.
SQL Server Mirroring
SQL Server Mirroring is a solution to improve the availability of SQL Server databases. It has three roles of Principal, Mirror, and Witness. The Principal can add, delete, change and check the database and provide read and write services to the outside world. The Mirror can only synchronize the database data from the Principal, and does not provide read and write services to the outside world. The Witness is used to automatically switch the role between Principal and Mirror nodes when Principal or Mirror fails.
SQL Server Always On
The Always On availability groups feature is a high-availability and disaster-recovery solution that provides an enterprise-level alternative to database mirroring. Introduced in SQL Server 2012 (11.x), Always On availability groups maximizes the availability of a set of user databases for an enterprise. An availability group supports a failover environment for a discrete set of user databases, known as availability databases, that fail over together.
MySQL Master-Slave Replication
MySQL Master-Slave Replication is a one-way replication (from master to slave). Only the master database is used for the write operations, while read operations may be spread on multiple slave databases. This means that if master-slave replication is used as the scale-out solution, you need to have at least two data sources defined, one for write operations and the second for read operations.
PostgreSQL Master-Slave Architectures
These architectures enable us to maintain an master database with one or more standby servers ready to take over operations if the primary server fails. These standby databases will remain synchronized with the master. The replication between the master and the slaves can be made via SQL statements or via the internal data structure modifications. PostgreSQL uses a stream of write-ahead log (WAL) records to keep the standby databases synchronized. If the main server fails, the standby contains almost all of the data of the main server, and can be quickly made the new master database server.
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High Availablity Database FAQs
Frequently asked questions about our HA database services.
What is a high availability database?
High Availability in a database refers to maintaining levels of uptime that exceed normal service level agreements. High availability databases achieve such uptime by eliminating single points of failure, reliably failing over to a redundant node, and monitoring for failures to initiate failover when needed.
Is mirroring the same as replication?
Mirroring refers to keeping copies of database to a geographically different location. Replication refers to creating multiple copies of data objects of a database for distribution efficiency. Mirroring is applicable on complete database as a whole
Is database mirroring deprecated in SQL Server 2016?
As of February 2016, Microsoft stated Database Mirroring would be removed in a future version of Microsoft SQL Server. Avoid using this feature in new development work, and plan to modify applications that currently use this feature. Use Always On Availability Groups instead.
What is the difference between mirroring and always on?
Essentially you had to choose between using database mirroring for disaster recovery (asynchronous) or for high availability(synchronous). AlwaysOn, however, allows up to two synchronous replicas and two asynchronous replicas to be simultaneously active.
The Always On availability groups feature is a high-availability and disaster-recovery solution that provides an enterprise-level alternative to database mirroring. Introduced in SQL Server 2012 (11.x), Always On availability groups maximizes the availability of a set of user databases for an enterprise. An availability group supports a failover environment for a discrete set of user databases, known as availability databases, that fail over together. An availability group supports a set of read-write primary databases and one to eight sets of corresponding secondary databases. Optionally, secondary databases can be made available for read-only access and/or some backup operations.
What is SQL mirroring?
Database mirroring maintains two copies of a single database that must reside on different server instances of SQL Server Database Engine. Typically, these server instances reside on computers in different locations.
What is SQL Server Always On?
SQL Server Always On is a marketing term that refers to the high availability and disaster recovery solution introduced when SQL Server 2012 was launched. To be more specific, SQL Server Always On consists of two technologies:AlwaysOn Failover Clustering Instances (AlwaysOn FCI) and Always On Availability Groups (AlwaysOn AG). Whilst both technologies have similarities, such as requiring Windows Server Failover Clustering (WSFC) as the foundation for its implementation, each is a distinct technologyunder the Always On umbrella.
Is mirroring supported in SQL Server 2019?
SQL Server Database Mirroring is a technology used for disaster recovery scenarios and is used by many DBAs. Even though Microsoft states that it is a deprecated feature, it is still hanging around in SQL Server 2019.
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Releated articles
Useful Resources about our SQL Server mirroring service.
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