Instances›AWS EC2›c5d›c5d.18xlarge
Compute
vCPUs72
Memory144 GiB
Mem / vCPU2.00 GiB
ProcessorXeon Platinum 8124M
Clock speed3.4 GHz
Architecturex86_64
Storage
Type2 × 900 GB NVMe SSD
Bandwidth19,000 Mbps
Throughput2375 MB/s
IOPS80,000
Networking
Performance25 Gigabit
Max ENIs15
IPv6Yes
GPUNone
Family sizes
c5d.large2 vCPU · 4 GiB
c5d.xlarge4 vCPU · 8 GiB
c5d.2xlarge8 vCPU · 16 GiB
c5d.4xlarge16 vCPU · 32 GiB
c5d.9xlarge36 vCPU · 72 GiB
c5d.12xlarge48 vCPU · 96 GiB
c5d.18xlarge72 vCPU · 144 GiB
c5d.24xlarge96 vCPU · 192 GiB
c5d.metal96 vCPU · 192 GiB
c5d.18xlarge

c5d.18xlarge is AWS's compute-optimized EC2 size at 72 vCPU and 144 GiB. In the name, "c" stands for compute, "5" is the generation, "d" marks local NVMe storage and "18xlarge" is the size within the c5d family. It runs on Intel Xeon Platinum 8124M at 3.4 GHz, and AWS introduced it in May 2018. AWS has since shipped c6i, c7i, c8i and c9g. The closest Spot shape is ch.vs1.2xlarge at 16 vCPU, so this instance maps to 5 of them — 80 vCPU and 160 GiB across the fleet, 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.

Match qualityScale-out match

c5d.18xlarge gives you 72 vCPU and 144 GiB in a single machine. The largest comparable Spot node, ch.vs1.2xlarge, is 16 vCPU and 32 GiB, so the equivalent here is 5 nodes rather than one.

Spot runs as managed Kubernetes, so a 5-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 72 cores and 144 GiB in one process, it does not.

No local diskc5d.18xlarge comes with 2 × 900 GB NVMe SSD attached to the machine. Spot nodes use network storage only, so that disk doesn't come with it. If you were using it as fast scratch space, you'd move to a persistent volume or object storage, which are slower to read.
Pricing by region
1 hr
RegionAWS on-demandAWS Spot1-yr Reserved3-yr ReservedRackspace SpotYou save
US East, N. Virginia$3.456$0.853$2.177$1.451$0.205
$3.251 savings
US Central, Chicagono AWS region$0.055
US Central, Dallasno AWS region$0.555
Hong Kong$4.428$2.790$1.913$0.205
$4.223 savings
Sydney, Australia$4.536$1.428$2.858$1.960$0.205
$4.331 savings
London, UK$4.140$0.881$2.608$1.788$0.655
$3.485 savings
US West, San Jose$4.320$1.232$2.722$1.866$0.009
$4.311 savings
US Central, Dallas 2no AWS region$0.549
US East, N. Virginia 2$3.456$0.853$2.177$1.451$0.729
$2.727 savings
When to use it
Good for
  • ●Ad serving and real-time bidding
  • ●Game servers and matchmaking
  • ●Batch processing and CI/CD runners
  • ●Workloads that fit inside 144 GiB of RAM
  • ●Jobs that want 2 × 900 GB of local NVMe scratch space
  • ●Network-heavy services — AWS rates this size at 25 Gigabit
  • ●Anything that shards cleanly across 5 nodes, which is how it maps onto Rackspace Spot
Avoid if
  • ●The working set needs more than 144 GiB of RAM
  • ●More than 2.00 GiB of RAM per vCPU is needed — that ratio is fixed for the whole family
  • ●The work is single-threaded. Most of these 72 vCPU would sit idle.
  • ●GPU or FPGA acceleration is needed
  • ●Memory-hungry applications. A memory-optimized family gives more RAM per dollar.
Stop overpaying AWS. This compute costs $2,523/mo on AWS vs $150/mo on Rackspace Spot.
  • 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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