AWS d3.8xlargevsAWS d3en.4xlarge

d3.8xlarge pairs 32 vCPUs with 256GB of RAM at $3.9955/hr On-Demand (about $2877/mo at 24×7). d3en.4xlarge pairs 16 vCPUs with 64GB at $2.1030/hr (~$1514/mo). d3en.4xlarge is 47% cheaper per hour than d3.8xlarge ($1.8925/hr gap).

Both are generation-3 storage-optimized (HDD) instances, but they run on different silicon: **d3.8xlarge** is Intel Xeon (x86_64), **d3en.4xlarge** is Intel Xeon (x86_64). AMD variants (suffix `a`) are typically 10% cheaper than Intel siblings at comparable single-thread performance. Graviton variants (suffix `g`) are usually 20–40% cheaper but require ARM64-compatible binaries — most modern Linux stacks are fine, but verify any compiled extensions, native modules, or third-party binaries before migrating. Same vCPU/RAM ratio, same network performance class, different processor.

On raw price-per-performance, the two are d3en.4xlarge delivers ~90% more single-thread Sysbench score per dollar (265 vs 503 points per $1/hr). That's the cleanest signal we have for "which one runs your workload faster per dollar," but it only matters if your workload is single-thread-bound; for parallel workloads the multi-core scores (26155 vs 13032) are what to weigh. Spot pricing flips many of these comparisons — when d3.8xlarge drops to $1.1133/hr and d3en.4xlarge drops to $0.5302/hr, the cheap-per-hour winner can swing meaningfully.

In practice, pick d3.8xlarge when your workload is closer to storage-optimized (HDD) (dense, sequential HDD storage — HDFS, MapReduce, log warehouses). Pick d3en.4xlarge when it's closer to storage-optimized (HDD) (dense, sequential HDD storage — HDFS, MapReduce, log warehouses). When neither side is obviously right, the cheaper hourly rate usually wins for fault-tolerant batch workloads, while the higher single-core score usually wins for latency-sensitive web traffic. The regional pricing tables linked from each instance page below show where each is currently cheapest — sometimes a >20% regional gap flips the comparison entirely.