btafabulous.blogg.se - Sql server 2012 enterprise edition version number

Multiple secondaries can also provide DR and reporting replicas.ĪlwaysOn uses the concept of Availability Groups and these may contain one or more databases that you wish to enable for HA. Ability to offload backup and maintenenace operations to secondary databases.īy offloading backup operations to read only replicas, you can reduce the I\O requirements on your production systems.The ability to suspend data movements at the primary level or individual secondary level.Better failover functionality leveraging Microsoft Windows Server Failover Clustering.Multiple availability databases instead of the traditional Principal\Mirror scenario.

AlwaysOn listener service to accept centralised requests to HA database groups.

No shared storage, each server\instance has localised storage and removes the storage Single Point Of Failure.

AlwaysOn takes the old database mirroring concept and creates a whole new level of HA, this encompasses the following Well, AlwaysOn (AO) is the new high availability technology from Microsoft in SQL Server 2012. You can combine other SQL Server availability technologies with fail over clusters, but think of the increased complexity. We have database mirroring in SQL Server versions prior to SQL Server 2012, but these only provide scope for a single nonreadable (with the exception of snapshots), secondary database. Of course, as previously mentioined, a fail over cluster only mitigates the server hardware, it does not provide a single or even multiple secondary databases. There are many ways to achieve redundancy here, but it usually comes at significant cost and it is often difficult to setup and maintain.

The only real weak link in the chain is the shared storage. multiple computer nodes to negate core node hardware failure (i.e.new Majority node set quorum models (available in Windows server 2003 SP1 onwards) to remove the disk dependency and increase support for multi site clusters.multiple network cards for network redundancy.With a clustered environment we are able to fully mitigate failures by utilising Anybody who has worked with high availability for SQL server over the years, will be fully aware of Microsoft Cluster Services (Windows 2003) and Windows Server Failover Clusters (Windows 2008).