AWS r5.metalvsAWS r5a.12xlarge

r5.metal pairs 96 vCPUs with 768GB of RAM at $6.0480/hr On-Demand (about $4355/mo at 24×7). r5a.12xlarge pairs 48 vCPUs with 384GB at $2.7120/hr (~$1953/mo). r5a.12xlarge is 55% cheaper per hour than r5.metal ($3.3360/hr gap).

Both are generation-5 memory-optimized instances, but they run on different silicon: **r5.metal** is Intel Xeon (x86_64), **r5a.12xlarge** is AMD EPYC (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.

Benchmark data for at least one of these instances is still being collected, so a direct performance-per-dollar comparison isn't possible yet. Sysbench scores are pending for r5.metal and 1258/31446 for r5a.12xlarge. Check back as the benchmark queue completes — newer-generation instances typically score 10–30% higher on single-thread and 15–50% higher on multi-core vs the previous generation in the same series.

In practice, pick r5.metal when your workload is closer to memory-optimized (memory-bound work — in-memory databases, real-time analytics, large caches). Pick r5a.12xlarge when it's closer to memory-optimized (memory-bound work — in-memory databases, real-time analytics, large caches). 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.