![]() There is one Primary Replica and one to four Secondary Replicas (eight for SQL 2014) (a Secondary Replica is a copy of databases from the Primary Replica, when a DB is modified, changes are replicated on all Secondary replica). The AG is also based on a WSFC cluster the difference is that on each node a SQL instance is installed and active.ĪAG is composed of replicas (a replica is a group of one or more database). The Availability Group feature is a mix of SQL Clustering and SQL Mirroring (it is also presented by MS as an alternative to SQL Mirroring which is deprecated since SQL Server 2012). ![]() I will write an article about AlwaysOn FCI with Windows 2012 R2 SOFS Storage (Scaled-Out File Server). The choice of use FCI or AAG depends of your Business requirement (RTO, RPO, DRP, Remote sites …)įor comparison, AlwaysOn Availability Groups doesn’t require Shared Storage. the Availability Group offer more options (like asynchronous replica, backup on secondary replica.it’s require additional storage skills for the operation team.it’s more complicated to implement on remote geographic sites.generates additional costs (this is also the case for AAG FCI is available on the SQL Standard version, AAG required an SQL Enterprise version) except if it’s included in your SAN license.For FCI across remote sites you need to implement SAN Replication.For FCI on the same site it’s possible to eliminate the Storage SPOF with SAN Replication.SQL Services (Instance) can failover between WSFC nodes (so the loss of a server is covered). In the FCI solution, Shared Storage is a SPOF (Single Point Of Failure). This storage must be configured on all nodes participating to an FCI. Clients connect to this instance from a VNN (Virtual Network Name) which is a Cluster resource.įCI required Shared Storage (SAN, SMB…) for database data and logs. In case of failure of a node, the instance will start on another node. FCI provide local high availability through redundancy at the server-instance level (a single instance installed across multiple nodes). This is the classic SQL Cluster based on the WSFC (Windows Server Failover Clustering) functionality. This part describes the new SQL High Availability feature introduced with SQL Server 2012 version: AlwaysOn Availability Group.įirst of all, do not confuse “AlwaysOn Availability Group” and “AlwaysOn FCI”. Part 9 – AlwaysOn Availability Groups – PowerShell Monitoring.Part 8 – Methods to add Database on Availability Groups (SCOM Example).Part 7 – AlwaysOn Availability Groups Creation (Advanced, with dedicated Replication Network).Part 6 – AlwaysOn Availability Groups Creation.Part 5 – Install SQL Core on Windows Core Server.Part 3 – Install and Configure Windows Server 2012 R2 in Core mode.SQL Server 2012/2014 AlwaysOn Availability Groups: ![]()
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