The c5.12xlarge is a compute-optimized AWS EC2 instance: 48 vCPU and 96 GiB of memory, 2.00 GiB per vCPU. In the name, "c" stands for compute, "5" is the generation and "12xlarge" is the size within the c5 family. It runs on Intel Xeon Platinum 8275L at 3.4 GHz, and AWS introduced it in June 2019. AWS has since shipped c6i, c7i, c8i and c9g; c6i.12xlarge is the direct replacement at this size, scoring 847,121 CoreMark/s against this instance's 789,311 — roughly 7% more throughput for the same vCPU count. No single Spot node covers 48 vCPU and 96 GiB, so the equivalent is a fleet: 3 × ch.vs1.2xlarge, 48 vCPU and 96 GiB in total, about 94% 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.
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c5.12xlarge gives you 48 vCPU and 96 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 48 cores and 96 GiB in one process, it does not.