Instances›AWS EC2›r8ib›r8ib.12xlarge
Compute
vCPUs48
Memory384 GiB
Mem / vCPU8.00 GiB
ProcessorXeon Scalable
Clock speed3.9 GHz
Architecturex86_64
Storage
TypeEBS only
Bandwidth37,500 Mbps
Throughput4687.5 MB/s
IOPS180,000
Networking
Performance50 Gigabit
Max ENIs12
IPv6Yes
GPUNone
Family sizes
r8ib.large2 vCPU · 16 GiB
r8ib.xlarge4 vCPU · 32 GiB
r8ib.2xlarge8 vCPU · 64 GiB
r8ib.4xlarge16 vCPU · 128 GiB
r8ib.8xlarge32 vCPU · 256 GiB
r8ib.12xlarge48 vCPU · 384 GiB
r8ib.16xlarge64 vCPU · 512 GiB
r8ib.24xlarge96 vCPU · 768 GiB
r8ib.32xlarge128 vCPU · 1024 GiB
r8ib.48xlarge192 vCPU · 1536 GiB
r8ib.metal-48xl192 vCPU · 1536 GiB
r8ib.96xlarge384 vCPU · 3072 GiB
r8ib.metal-96xl384 vCPU · 3072 GiB
r8ib.12xlarge

r8ib.12xlarge is AWS's memory-optimized EC2 size at 48 vCPU and 384 GiB. In the name, "r" stands for RAM, "8" is the generation, "ib" marks Intel processors and block-storage optimisation and "12xlarge" is the size within the r8ib family. It runs on Intel Xeon Scalable (Granite Rapids) at 3.9 GHz, and AWS introduced it in April 2026. AWS has since shipped r9g; r9g.12xlarge is the direct replacement at this size. The closest Spot shape is mh.vs1.2xlarge at 16 vCPU, so this instance maps to 3 of them — 48 vCPU and 384 GiB across the fleet, $5.02/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

r8ib.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.

Pricing by region
1 hr
RegionAWS on-demandAWS Spot1-yr Reserved3-yr ReservedRackspace SpotYou save
US East, N. Virginia$5.021$2.027$0.063
$4.958 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$6.025$2.720$0.006
$6.019 savings
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 50 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
  • ●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
  • ●GPU or FPGA acceleration is needed
r8ib.12xlarge runs $3,665/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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