Choosing EC2 instances shouldn't be a guessing game. Here's my practical approach to picking the right instance types that balance cost and performance.
Understanding Instance Families
EC2 instances come in families optimized for different workloads. General purpose (t3, m5), compute optimized (c5), memory optimized (r5), storage optimized (i3), and more. Pick the family that matches your workload.
My Decision Framework
1. Identify your workload type (CPU-bound, memory-bound, network-bound, storage-bound). 2. Test different instance types in your actual workload. 3. Use CloudWatch metrics to see actual resource usage. 4. Start small, scale up if needed. 5. Consider Reserved Instances for predictable workloads.
Common Mistakes
Oversizing "just to be safe" - costs more, doesn't help. Picking by name without understanding requirements. Not testing before committing to large deployments.
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