Database Reference
In-Depth Information
Figure 2-1.
SQL Azure topology
Figure 2-1 illustrates that connections are made through a load balancer that determines which
gateway should process the connection request. The gateway acts as a firewall by inspecting the request,
performing authentication and authorization services, and forwarding the packets to an actual SQL
Azure database. Because databases can be moved dynamically to ensure fair resource allocation, the
gateway may alter the destination endpoint. The process is mostly transparent.
In addition, each SQL Azure database is replicated twice on different servers for redundancy. Behind
the scenes, a replication topology ensures that a SQL Azure database exists on two other physical servers
at all times. These two additional copies are totally transparent to consumers and can't be accessed.
Note
SQL Azure offers 99.9% availability.
Performance
Performance of applications you write can be affected by two things: throttling and how you design the
application. Microsoft has put
performance throttling
in place to prevent one client's applications from
impacting another. (It's a good feature, not nearly so bad as it may sound.) Application design is
something you control.
