i need your help here please with AlwaysOn architecture.
Here is what we currently have:
Traditional 4 node cluster1 with 3 instances running on 3 nodes (1 instance on each node) and 1 spare node for HA in 1 datacenter1.
The cluster1 is attached to SAN.
Then we have asynchronius mirroring setup from cluster1 to datacenter2 for each database on each instance.
We will be upgrading soon to sql server 2012 and decided that we could use AlwaysOn availablity groups for DR,
but i am a little confused what will be the best architecture for our case.
Basically the requirements for this 24x7 (e-comm application) are:
1) Automatic failover between servers with zero data loss and no performance degradation in datacenter1 first
and if datacenter1 is not available then manual failover with some data loss to datacenter2 is acceptable.
2) We currently have transactional replication but could use one of the secondary readable replica instead of replication.
It is possible to do so to remove replication completly?
Can you please help me with high leve design for this case?
Also, what i don't undestand is what is the difference and in which case each of these below should be used?:
1) Availability Group for HA and DR
2) Failover Cluster Instance for local HA and Availability Group for DR