Instances›AWS EC2›r8gn›r8gn.12xlarge
Compute
vCPUs48
Memory384 GiB
Mem / vCPU8.00 GiB
ProcessorGraviton4 Processor
Clock speed2.8 GHz
Architecturearm64
Storage
TypeEBS only
Bandwidth30,000 Mbps
Throughput3750 MB/s
IOPS120,000
Networking
Performance150 Gigabit
Max ENIs12
IPv6Yes
GPUNone
Family sizes
r8gn.medium1 vCPU · 8 GiB
r8gn.large2 vCPU · 16 GiB
r8gn.xlarge4 vCPU · 32 GiB
r8gn.2xlarge8 vCPU · 64 GiB
r8gn.4xlarge16 vCPU · 128 GiB
r8gn.8xlarge32 vCPU · 256 GiB
r8gn.12xlarge48 vCPU · 384 GiB
r8gn.16xlarge64 vCPU · 512 GiB
r8gn.24xlarge96 vCPU · 768 GiB
r8gn.metal-24xl96 vCPU · 768 GiB
r8gn.48xlarge192 vCPU · 1536 GiB
r8gn.metal-48xl192 vCPU · 1536 GiB
r8gn.12xlarge

The r8gn.12xlarge is a memory-optimized AWS EC2 instance: 48 vCPU and 384 GiB of memory, 8.00 GiB per vCPU. In the name, "r" stands for RAM, "8" is the generation, "gn" marks AWS Graviton (ARM) processors and enhanced networking and "12xlarge" is the size within the r8gn family. It runs on AWS Graviton4 Processor at 2.8 GHz, and AWS introduced it in September 2025. AWS has since shipped r9g; r9g.12xlarge is the direct replacement at this size. No single Spot node covers 48 vCPU and 384 GiB, so the equivalent is a fleet: 3 × mh.vs1.2xlarge, 48 vCPU and 384 GiB in total, $4.37/hr on AWS in US East (N. Virginia), from $0.063/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

r8gn.12xlarge gives you 48 vCPU and 384 GiB in a single machine. The largest comparable Spot node, mh.vs1.2xlarge, is 16 vCPU and 128 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 384 GiB in one process, it does not.

x86_64 onlyr8gn.12xlarge 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.
Pricing by region
1 hr
RegionAWS on-demandAWS Spot1-yr Reserved3-yr ReservedRackspace SpotYou save
US East, N. Virginia$4.372$0.968$0.063
$4.309 savings
US Central, Chicagono AWS region$0.063
US Central, Dallasno AWS region$0.393
Hong Kong$0.063
Sydney, Australia$0.063
London, UK$0.393
US West, San Jose$0.006
US Central, Dallas 2no AWS region$0.726
When to use it
Good for
  • ●Real-time analytics over hot datasets
  • ●Database instances that keep the working set in RAM
  • ●Graph and search workloads with large indexes
  • ●Workloads that fit inside 384 GiB of RAM
  • ●Parallel work that can occupy 48 vCPU
  • ●Network-heavy services — AWS rates this size at 150 Gigabit
  • ●Anything that shards cleanly across 3 nodes, which is how it maps onto Rackspace Spot
Avoid if
  • ●The working set needs more than 384 GiB of RAM
  • ●You cannot rebuild x86-only binaries or vendor images for aarch64
  • ●CPU-bound work. You are paying for memory this workload will not use.
  • ●More than 8.00 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.
  • ●Local NVMe or instance-store disk is a hard requirement
r8gn.12xlarge runs $3,192/mo on AWS on-demand. The 3-node equivalent on Rackspace Spot: $46/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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