SQL Server
provides several options for creating high availability for a server or
database. The high-availability options include the following:
AlwaysOn
Failover Cluster Instances (support version Enterprise, BI & Standard)
As part of the
SQL Server AlwaysOn offering, AlwaysOn Failover Cluster Instances leverages
Windows Server Failover Clustering (WSFC) functionality to provide local high
availability through redundancy at the server-instance level—a failover cluster
instance (FCI). An FCI is a single instance of SQL Server that is installed
across Windows Server Failover Clustering (WSFC) nodes and, possibly, across
multiple subnets. On the network, an FCI appears to be an instance of SQL
Server running on a single computer, but the FCI provides failover from one
WSFC node to another if the current node becomes unavailable.
For more
information, see AlwaysOn Failover Cluster Instances (SQL Server).
AlwaysOn
Availability Groups (Only Enterprise)
AlwaysOn
Availability Groups is an enterprise-level high-availability and disaster
recovery solution introduced in SQL Server 2012 to enable you to maximize
availability for one or more user databases. AlwaysOn Availability Groups
requires that the SQL Server instances reside on Windows Server Failover
Clustering (WSFC) nodes.
For more
information, see AlwaysOn Availability Groups (SQL Server).
Database
mirroring (support version Enterprise, BI & Standard)
Database
mirroring is a solution to increase database availability by supporting almost
instantaneous failover. Database mirroring can be used to maintain a single
standby database, or mirror database, for a corresponding production database
that is referred to as the principal database.
For more
information, see Database Mirroring (SQL Server).
Log shipping (support
version Enterprise, BI & Standard)
Like AlwaysOn
Availability Groups and database mirroring, log shipping operates at the database level. You can use log
shipping to maintain one or more warm standby databases (referred to as secondary
databases) for a single production database that is referred to as the primary
database.
For more
information about log shipping, see About
Log Shipping (SQL Server).
Microsoft recommendation
for providing data protection for your SQL Server environment are as follows:
- For data protection through a
third-party shared disk solution (a SAN), we recommend that you use
AlwaysOn Failover Cluster Instances.
- For data protection through SQL
Server, we recommend that you use AlwaysOn Availability Groups.
