How to Handle Failures in Distributed Systems

Apr 03, 2025

∙ Paid

In a distributed system, failures aren’t a possibility—they’re a certainty.

Your database might go down. A service might become unresponsive. A network call might time out. The question is not if these things will happen—but when.

As engineers, our job is to design systems that embrace this reality and gracefully handle failures.

In this article, we’ll cover:

Types of failures in distributed systems
12 best strategies for handling failures

Types of Failures in Distributed Systems

Distributed systems involve multiple independent components communicating over a network.

And each of these introduces potential failure points:

1. Network Failures

The network is the most unreliable component in any distributed architecture.

Packets get dropped
Connections time out
DNS resolution fails
Latency spikes suddenly
Firewalls misbehave

Even if two services are running in the same data center, network glitches can still occur.

2. Node Failures

A single machine (or container) can go down due to:

Power failure
OS crash
Disk corruption
Out-of-memory (OOM)
Hardware failure

In distributed systems, every node is potentially a single point of failure unless redundancy is built in.

3. Service Failures

A service may fail even if the machine it's running on is healthy.

Common reasons:

Code bugs (null pointers, unhandled exceptions)
Deadlocks or resource exhaustion
Memory leaks causing the service to slow down or crash
Misconfigurations (e.g., bad environment variables)

4. Dependency Failures

Most services depend on:

Databases
Caches (like Redis or Memcached)
External APIs (payment gateways, 3rd-party auth providers)
Message queues (like Kafka, RabbitMQ)

If any of these are unavailable, misbehaving, or inconsistent, it can cause cascading failures across the system.

Example: Your checkout service calls the payment API, which calls a bank API, which calls a fraud-detection microservice. Each hop is a potential point of failure.

5. Data Inconsistencies

Data replication across systems (like DB sharding, caching layers, or eventual consistency models) can introduce:

Out-of-sync states
Stale reads
Phantom writes
Lost updates due to race conditions

Example: A user updates their address, but due to replication lag, the shipping system fetches the old address and sends the package to the wrong place.

6. Configuration & Deployment Errors

Failures aren't always caused by bugs—they’re often caused by mis-configurations and human errors:

Misconfigured load balancers
Missing secrets in the environment
Incompatible library updates
Deleting the wrong database
Rolling out a new version without backward compatibility

According to multiple incident postmortems (e.g., AWS, Google), a large number of production outages are triggered by bad config changes—not code.

7. Time-Related Issues (Clock Skew, Timeouts)

Distributed systems often rely on time for:

Cache expiration
Token validation
Event ordering
Retry logic

But system clocks on different machines can drift out of sync (called clock skew), which can wreak havoc.

Example:

Machine A: 12:00:01
Machine B: 11:59:59

A token generated on Machine B might be considered “expired” when validated by Machine A, even if it was just created.

12 Best Strategies for Handling Failures

Let’s look at the 12 best strategies that make your system resilient when parts of it inevitably fail.

1. Set Timeouts for Remote Calls

A timeout is the maximum time you’re willing to wait for a response from another service. If a service doesn’t respond in that time window, you abort the operation and handle it as a failure.

Every network call whether it’s to a REST API, database, message queue, or third-party service should have a timeout.

Why?

Waiting too long can hog threads, pile up requests, and cause cascading failures. It’s better to fail fast and try again (smartly).

Timeout Best Practices

To be effective, timeouts should be:

Short enough to fail fast
Long enough for the request to realistically complete
Vary depending on the operation (e.g., reads vs writes, internal vs external calls)

A good practice is to base timeouts on the service’s typical latency (e.g., use the 99th percentile response time or service SLO, plus a safety margin).