Instances›AWS EC2›c5n›c5n.4xlarge
Compute
vCPUs16
Memory42 GiB
Mem / vCPU2.63 GiB
ProcessorXeon Platinum 8124M
Clock speed3 GHz
Architecturex86_64
Storage
TypeEBS only
Bandwidth4,750 Mbps
Throughput593.75 MB/s
IOPS20,000
Networking
PerformanceUp to 25 Gigabit
Max ENIs8
IPv6Yes
GPUNone
Family sizes
c5n.large2 vCPU · 5.25 GiB
c5n.xlarge4 vCPU · 10.5 GiB
c5n.2xlarge8 vCPU · 21 GiB
c5n.4xlarge16 vCPU · 42 GiB
c5n.9xlarge36 vCPU · 96 GiB
c5n.18xlarge72 vCPU · 192 GiB
c5n.metal72 vCPU · 192 GiB
c5n.4xlarge

The c5n.4xlarge is a compute-optimized AWS EC2 instance: 16 vCPU and 42 GiB of memory, 2.63 GiB per vCPU. In the name, "c" stands for compute, "5" is the generation, "n" marks enhanced networking and "4xlarge" is the size within the c5n family. It runs on Intel Xeon Platinum 8124M at 3 GHz, and AWS introduced it in November 2018. AWS has since shipped c6i, c7i, c8i and c9g; c6i.4xlarge is the direct replacement at this size, scoring 276,865 CoreMark/s against this instance's 253,425 — roughly 9% more throughput for the same vCPU count. No single Spot node covers 16 vCPU and 42 GiB, so the equivalent is a fleet: 2 × ch.vs1.2xlarge, 32 vCPU and 64 GiB in total, about 91% 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

c5n.4xlarge gives you 16 vCPU and 42 GiB in a single machine. The largest comparable Spot node, ch.vs1.2xlarge, is 16 vCPU and 32 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 16 cores and 42 GiB in one process, it does not.

Pricing by region
1 hr
RegionAWS on-demandAWS Spot1-yr Reserved3-yr ReservedRackspace SpotYou save
US East, N. Virginia$0.864$0.334$0.544$0.314$0.082
$0.782 savings
US Central, Chicagono AWS region$0.022
US Central, Dallasno AWS region$0.222
Hong Kong$1.144$0.721$0.446$0.082
$1.062 savings
Sydney, Australia$1.128$0.431$0.711$0.437$0.082
$1.046 savings
London, UK$1.024$0.374$0.645$0.428$0.262
$0.762 savings
US West, San Jose$1.080$0.309$0.680$0.434$0.003
$1.077 savings
US Central, Dallas 2no AWS region$0.183
US East, N. Virginia 2$0.864$0.334$0.544$0.314$0.243
$0.621 savings
When to use it
Good for
  • ●High-traffic web and API serving
  • ●Scientific modelling and simulation
  • ●Ad serving and real-time bidding
  • ●Workloads that fit inside 42 GiB of RAM
  • ●Parallel work that can occupy 16 vCPU
  • ●Network-heavy services — AWS rates this size at Up to 25 Gigabit
  • ●Anything that shards cleanly across 2 nodes, which is how it maps onto Rackspace Spot
Avoid if
  • ●Starting a new deployment. c6i.4xlarge is the newer generation at this size.
  • ●The working set needs more than 42 GiB of RAM
  • ●The work is single-threaded. Most of these 16 vCPU would sit idle.
  • ●Local NVMe or instance-store disk is a hard requirement
  • ●GPU or FPGA acceleration is needed
  • ●Memory-hungry applications. A memory-optimized family gives more RAM per dollar.
$631/mo on AWS on-demand against $60/mo on Rackspace Spot for the 2-node equivalent — market-priced, not list-priced.
  • Spot sells spare capacity at market prices. It is the cheapest compute on the internet.
  • Prices are set by supply and demand. You pay what the market decides.
  • Compute is delivered as fully managed Kubernetes. All infrastructure is taken care of.
  • Egress costs $0.01/GB after the free allowance. AWS charges $0.09/GB.
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