availability-deploy-concerns.md

Availability Deploy Concerns

Decision

We should employ load balancers internally to our services and also consider Global Server Load Balancing (GSLB) and deploying our system into data-centers on separate regions to ensure high availability, global scalability, and improved user experience for end users

Pros

• LBs provide fault tolerance and high availability (availability, fault tolerance)
• LBs can route requests to the appropriate instance (e.g. based on available resources considerations) that can handle them most efficiently (performance)
• LBs support horizontal scaling by allowing new servers or instances to be added to the pool (scalability)
• GSLB routes client requests to the closest data center to improve the availability and responsiveness of services (responsiveness)

Cons

• Introduce an additional network hop, which can increase latency (performance)
• Load balancing services have ongoing usage or hardware costs (cost)
• GSLB configurations can be complex, particularly in large and distributed environments with multiple data centers

Justification

Ultimately we need to consider supporting multiple disparate geographic distributed data centers in multiple regions. Since availability is a core quality attribute for our system, we need to ensure that our system can cope with failures increased traffic and be responsive to globally distributed end users.