The c5.9xlarge pairs 36 vCPU with 72 GiB of RAM, the 2.00 GiB-per-vCPU ratio that marks a compute-optimized instance. In the name, "c" stands for compute, "5" is the generation and "9xlarge" is the size within the c5 family. It runs on Intel Xeon Platinum 8124M at 3.4 GHz, and AWS introduced it in November 2017. AWS has since shipped c6i, c7i, c8i and c9g. Spot's node ladder tops out below this size, so c5.9xlarge becomes 3 × ch.vs1.2xlarge (48 vCPU, 96 GiB combined), about 92% below the US East (N. Virginia) on-demand rate. 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
c5.9xlarge gives you 36 vCPU and 72 GiB in a single machine. The largest comparable Spot node, ch.vs1.2xlarge, is 16 vCPU and 32 GiB, so the equivalent here is 3 nodes rather than one.
Spot runs as managed Kubernetes, so a 3-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 36 cores and 72 GiB in one process, it does not.
