Thursday, September 21, 2017

SQL Server AlwaysOn & Failover scenarios


SQL Server AlwaysOn Architecture
SQL Server AlwaysOn is recommended for high availability, zero data loss protection, automatic failover of multiple databases

Figure 1: SQL Server AlwaysOn between 2 SQL Servers

SQL Server AlwaysOn & Failover scenarios 
Case -1: When SQL Server A is down
It will switch to SQL Server B with AlwaysOn
SQL Server B will keep use the SAN B


Case -2: When SAN A is down
SQL Server A will be down
It will switch to SQL Server B with AlwaysOn
SQL Server B will keep use the SAN B


Case -3: When SQL Server B is down
It will switch to Server A with AlwaysOn
Server A will keep use the SAN A


Case -4: When SAN B is down
SQL Server B will be down
It will switch to Server A with AlwaysOn
Server A will keep use the SAN A