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 ServersSQL 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