Instances›AWS EC2›c5ad›c5ad.12xlarge
Compute
vCPUs48
Memory96 GiB
Mem / vCPU2.00 GiB
ProcessorEPYC 7R32
Clock speed3.3 GHz
Architecturex86_64
Storage
Type2 × 900 GB NVMe SSD
Bandwidth4,750 Mbps
Throughput593.75 MB/s
IOPS20,000
Networking
Performance12 Gigabit
Max ENIs8
IPv6Yes
GPUNone
Family sizes
c5ad.large2 vCPU · 4 GiB
c5ad.xlarge4 vCPU · 8 GiB
c5ad.2xlarge8 vCPU · 16 GiB
c5ad.4xlarge16 vCPU · 32 GiB
c5ad.8xlarge32 vCPU · 64 GiB
c5ad.12xlarge48 vCPU · 96 GiB
c5ad.16xlarge64 vCPU · 128 GiB
c5ad.24xlarge96 vCPU · 192 GiB
c5ad.12xlarge

The c5ad.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, "ad" marks AMD processors and local NVMe storage and "12xlarge" is the size within the c5ad family. It runs on AMD EPYC 7R32 at 3.3 GHz, and AWS introduced it in August 2020. AWS has since shipped c6i, c7i, c8i and c9g; c6i.12xlarge is the direct replacement at this size. 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.

Match qualityScale-out match

c5ad.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.

No local diskc5ad.12xlarge 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$2.064$0.805$1.300$0.892$0.123
$1.941 savings
US Central, Chicagono AWS region$0.033
US Central, Dallasno AWS region$0.333
Hong Kong$0.123
Sydney, Australia$2.712$0.960$1.709$1.172$0.123
$2.589 savings
London, UK$0.393
US West, San Jose$0.006
US Central, Dallas 2no AWS region$0.366
US East, N. Virginia 2$2.064$0.805$1.300$0.892$0.486
$1.578 savings
When to use it
Good for
  • ●Scientific modelling and simulation
  • ●Ad serving and real-time bidding
  • ●Game servers and matchmaking
  • ●Workloads that fit inside 96 GiB of RAM
  • ●Jobs that want 2 × 900 GB of local NVMe scratch space
  • ●Network-heavy services — AWS rates this size at 12 Gigabit
  • ●Anything that shards cleanly across 3 nodes, which is how it maps onto Rackspace Spot
Avoid if
  • ●Starting a new deployment. c6i.12xlarge is the newer generation at this size.
  • ●The working set needs more than 96 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 48 vCPU would sit idle.
  • ●GPU or FPGA acceleration is needed
  • ●Memory-hungry applications. A memory-optimized family gives more RAM per dollar.
c5ad.12xlarge runs $1,507/mo on AWS on-demand. The 3-node equivalent on Rackspace Spot: $90/mo.
  • 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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