Data Centers in System Design
Learn how data centers work in system design, covering multi-center setups, geo-routing, data synchronization, and failover strategies.
What is a Data Center?
A data center is a building full of computers, which includes:
Thousands of servers
Storage systems
Network equipment
Power supplies
Cooling systems
Physical security measures
In many distributed systems, we use more than one data center to improve reliability and speed.
Multi-Data Center Architecture
Let’s look at a typical setup with two data centers:
One in the US-East (perhaps Virginia)
One in the US-West (perhaps Oregon)
This setup adds redundancy and provides the best possible user experience. Here’s how:
1. Users automatically connect to their nearest data center
2. These data centers might also have shared storage
3. Each center can handle full capacity if needed
GeoDNS — The Traffic Director
But how do we make sure that each user connects to their nearest data center?
There’s a system called GeoDNS, which is like a traffic cop but for the internet:
It’s a smart DNS service that determines user location.
Then, it routes to the nearest data center.
Which reduces latency significantly and also handles automatic failover
So, all user requests are directed through a load balancer, which then routes them geographically according to their location.
Handling Failover Scenarios
But what happens when things go wrong? Let’s say our US-West data center goes offline.
In such instances, failover mechanisms are in place to manage these scenarios:
Automatic detection systems identify the failure
GeoDNS immediately updates routing rules to direct 100% to US-East
And this makes sure that users experience minimal disruption.
Scaling Strategies
Now, let’s discuss how to scale multi-data center systems. There are two primary strategies for effectively scaling such systems:
1. The first option is by component decoupling
Breaking down monolithic applications into microservices architecture
This allows us independent scaling of components (microservices) in a multi-data center architecture
2. The next option is to use messaging architecture with message queues
This allows asynchronous processing and load leveling
And we can also use event-driven architecture in this case
Real-World Examples
Now let’s look at some examples of how major companies implement these concepts:
For example, Netflix uses a multi-region active-active setup. In a typical operating state, users are GeoDNS routed to the nearest region, typically with a 50/50 distribution. If one of these data centers becomes unavailable, there are tools available to bypass GeoDNS and redirect all user traffic to a functioning region.
Another example is Amazon, which organizes its services using availability zones within regions. Each region represents a physical location around the world housing data centers. An availability zone consists of one or more data centers equipped with redundant power, networking, and connectivity within an AWS region. This structure allows AWS regions to offer more scalability compared to operating from a single data center.
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