Instances›AWS EC2›im4gn›im4gn.16xlarge
Compute
vCPUs64
Memory256 GiB
Mem / vCPU4.00 GiB
ProcessorGraviton2 Processor
Clock speed2.5 GHz
Architecturearm64
Storage
Type4 × 7,500 GB NVMe SSD
Bandwidth40,000 Mbps
Throughput5000 MB/s
IOPS160,000
Networking
Performance100 Gigabit
Max ENIs15
IPv6Yes
GPUNone
Family sizes
im4gn.large2 vCPU · 8 GiB
im4gn.xlarge4 vCPU · 16 GiB
im4gn.2xlarge8 vCPU · 32 GiB
im4gn.4xlarge16 vCPU · 64 GiB
im4gn.8xlarge32 vCPU · 128 GiB
im4gn.16xlarge64 vCPU · 256 GiB
im4gn.16xlarge

The im4gn.16xlarge pairs 64 vCPU with 256 GiB of RAM, the 4.00 GiB-per-vCPU ratio that marks a storage-optimized instance. In the name, "4" is the generation, "gn" marks AWS Graviton (ARM) processors and enhanced networking and "16xlarge" is the size within the im4gn family. It runs on AWS Graviton2 Processor at 2.5 GHz, and AWS introduced it in November 2021. im4gn is the current generation of the im family, so there is no newer AWS size to migrate to. Spot's node ladder tops out below this size, so im4gn.16xlarge becomes 4 × gp.vs1.2xlarge (64 vCPU, 256 GiB combined), $5.82/hr on AWS in US East (N. Virginia), from $0.164/hr on Rackspace Spot. 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

im4gn.16xlarge gives you 64 vCPU and 256 GiB in a single machine. The largest comparable Spot node, gp.vs1.2xlarge, is 16 vCPU and 64 GiB, so the equivalent here is 4 nodes rather than one.

Spot runs as managed Kubernetes, so a 4-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 64 cores and 256 GiB in one process, it does not.

x86_64 onlyim4gn.16xlarge is Graviton (arm64) and Rackspace Spot has no arm64 nodes, so you'd be moving to x86. You'll need x86 builds of your images, and per-core speed differs between the chips — worth testing before you decide how many nodes to run.
No local diskim4gn.16xlarge comes with 4 × 7,500 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$5.821$0.902$3.733$2.661$0.164
$5.657 savings
US Central, Chicagono AWS region$0.164
US Central, Dallasno AWS region$0.204
Hong Kong$0.044
Sydney, Australia$6.977$0.698$4.502$3.193$0.644
$6.333 savings
London, UK$6.753$0.705$4.356$3.079$0.884
$5.869 savings
US West, San Jose$0.604
US Central, Dallas 2no AWS region$0.004
US East, N. Virginia 2$5.821$0.902$3.733$2.661$0.604
$5.217 savings
When to use it
Good for
  • ●Streaming ingest that spools to local disk
  • ●Elasticsearch and OpenSearch data nodes
  • ●NoSQL stores such as Cassandra, ScyllaDB and MongoDB
  • ●Workloads that fit inside 256 GiB of RAM
  • ●Jobs that want 4 × 7,500 GB of local NVMe scratch space
  • ●Network-heavy services — AWS rates this size at 100 Gigabit
  • ●Anything that shards cleanly across 4 nodes, which is how it maps onto Rackspace Spot
Avoid if
  • ●The working set needs more than 256 GiB of RAM
  • ●You cannot rebuild x86-only binaries or vendor images for aarch64
  • ●GPU or FPGA acceleration is needed
  • ●Workloads that never touch local disk. The instance-store premium is wasted.
  • ●More than 4.00 GiB of RAM per vCPU is needed — that ratio is fixed for the whole family
  • ●The work is single-threaded. Most of these 64 vCPU would sit idle.
$4,249/mo on AWS on-demand against $120/mo on Rackspace Spot for the 4-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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