Navigating System Design: Our Thoughts on Building Scalable Systems

Engineers constantly find themselves balancing performance, scalability, and reliability.

So, let’s dive into some key system design concepts that we believe are crucial for any growing system.

1. The Power and Pitfalls of Caching

We’ve all been there. You build an app, traffic picks up, and suddenly your database is buckling under the weight of endless read requests. The solution? Caching. It’s one of the simplest yet most powerful tools in system design. By introducing a fast cache layer—think Redis or Memcached—we can dramatically reduce database load. But caching isn’t magic. Keeping the cache in sync with the database and managing cache expiration are constant challenges. Strategies like time-to-live (TTL) or write-through caching have saved us more than once. We’ve learned that caching works best for read-heavy, low-churn data, like static pages or product listings.

2. Taming the Write-Heavy Beasts

On the flip side, some systems get slammed with write operations—like logging systems that process millions of events per second. Handling this kind of load requires a different approach. We’ve found that asynchronous writing, using message queues and background workers, helps maintain a smooth user experience. Users get instant feedback, while heavy lifting happens behind the scenes. Databases like Cassandra, built on LSM-Tree architecture, have been a go-to for handling high write loads. They collect writes in memory and periodically flush them to disk, ensuring fast writes even under pressure.

3. Building Resilient Systems: Redundancy and Failover

We all know the sinking feeling when a critical system goes down. That’s why redundancy and failover are non-negotiable in our designs. Implementing primary-replica setups for databases has saved us more than once. While synchronous replication ensures data consistency, asynchronous replication offers better performance—with a slight risk of data loss. It’s all about finding the right balance based on system requirements. Load balancers also play a key role here, distributing traffic and rerouting it in case of server failures.

4. Global Performance: CDNs and Edge Computing

Serving a global audience brings its own set of challenges. We’ve seen firsthand how users on the other side experience painfully slow load times if content isn’t optimized. Content Delivery Networks (CDNs) have been a game-changer for many industries. By caching static content closer to users, we drastically cut latency. For dynamic content, edge computing has helped us process data closer to the user, improving performance even further.

5. Smart Storage Strategies

Choosing the proper storage solution is crucial when dealing with massive amounts of data. We typically use a mix of block storage and object storage. Block storage gives us low latency for databases, while object storage—like AWS S3—handles large static files cost-effectively. Balancing these storage types ensures we meet both performance and budget goals.

6. Monitoring and Observability

A well-designed system is only as good as its monitoring. We rely heavily on tools like Prometheus for metrics and Grafana for visualization. Distributed tracing with OpenTelemetry has been invaluable in pinpointing bottlenecks. One thing we’ve learned is that monitoring everything isn’t the goal. It’s about focusing on key metrics and setting up intelligent alerts that flag real issues without overwhelming us with noise.

7. Optimizing Database Performance

Slow database queries are a common pain point. Indexing is often the first fix we try, and it works wonders—until it doesn’t. Every index speeds up reads but slows down writes, so it’s a balancing act. When indexing isn’t enough, we do sharding, splitting the database across multiple machines. Tools like Vitess have made sharding MySQL databases much more effortless.

8. Preparing for the Unknown

If there’s one thing we’ve learned, no system is perfect. Failures will happen. What sets excellent systems apart is how they handle those failures. Designing for resilience, planning for scaling, and always being ready to adapt—that’s what makes all the difference.

We hope these insights resonate with you and may help you in your next system design challenge. We’d love to hear your thoughts—what strategies have worked for you? What challenges are you tackling right now?

Let’s keep the conversation going, keep experimenting, and, most importantly—stay curious.

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