The r5a.8xlarge pairs 32 vCPU with 256 GiB of RAM, the 8.00 GiB-per-vCPU ratio that marks a memory-optimized instance. In the name, "r" stands for RAM, "5" is the generation, "a" marks AMD processors and "8xlarge" is the size within the r5a family. It runs on AMD EPYC 7571 at 2.5 GHz, and AWS introduced it in June 2019. AWS has since shipped r6a, r7a, r8a and r9g; r6a.8xlarge is the direct replacement at this size, scoring 648,068 CoreMark/s against this instance's 407,695 — roughly 59% more throughput for the same vCPU count. Spot's node ladder tops out below this size, so r5a.8xlarge becomes 2 × mh.vs1.2xlarge (32 vCPU, 256 GiB combined), $1.81/hr on AWS in US East (N. Virginia), from $0.042/hr on Rackspace Spot. Spot delivers compute as managed Kubernetes, so a node pool of that size is the native shape of the answer rather than a workaround — provided the workload scales horizontally.
Match qualityScale-out match
r5a.8xlarge gives you 32 vCPU and 256 GiB in a single machine. The largest comparable Spot node, mh.vs1.2xlarge, is 16 vCPU and 128 GiB, so the equivalent here is 2 nodes rather than one.
Spot runs as managed Kubernetes, so a 2-node pool is the normal way to run things rather than a workaround. If your workload already sits behind a load balancer, a queue or a scheduler, it spreads across them without changes. If it needs all 32 cores and 256 GiB in one process, it does not.
