Instances›AWS EC2›r8gn›r8gn.4xlarge
Compute
vCPUs16
Memory128 GiB
Mem / vCPU8.00 GiB
ProcessorGraviton4 Processor
Clock speed2.8 GHz
Architecturearm64
Storage
TypeEBS only
Bandwidth10,000 Mbps
Throughput1250 MB/s
IOPS40,000
Networking
Performance50 Gigabit
Max ENIs8
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.4xlarge

The r8gn.4xlarge pairs 16 vCPU with 128 GiB of RAM, the 8.00 GiB-per-vCPU ratio that marks a memory-optimized instance. In the name, "r" stands for RAM, "8" is the generation, "gn" marks AWS Graviton (ARM) processors and enhanced networking and "4xlarge" 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.4xlarge is the direct replacement at this size. mh.vs1.2xlarge on Rackspace Spot lines up one-for-one: 16 vCPU and 128 GiB, $1.46/hr on AWS in US East (N. Virginia), from $0.021/hr on Rackspace Spot.

Match qualityx86 substitution

r8gn.4xlarge is Graviton (arm64). Rackspace Spot does not have arm64 servers, so mh.vs1.2xlarge is an x86_64 substitute with similar specs.

You will need x86 builds of your container images. Most software rebuilds without changes, but anything with compiled native code needs a real rebuild rather than a retag. Speed per core also differs between the two chips, so it is worth testing before deciding how many nodes to run.

Pricing by region
1 hr
RegionAWS on-demandAWS Spot1-yr Reserved3-yr ReservedRackspace SpotYou save
US East, N. Virginia$1.457$0.589$0.021
$1.436 savings
US Central, Chicagono AWS region$0.021
US Central, Dallasno AWS region$0.131
Hong Kong$0.021
Sydney, Australia$0.021
London, UK$0.131
US West, San Jose$0.002
US Central, Dallas 2no AWS region$0.242
When to use it
Good for
  • ●Graph and search workloads with large indexes
  • ●In-memory caches such as Redis and Memcached
  • ●Large JVM heaps and application servers that hold state
  • ●Workloads that fit inside 128 GiB of RAM
  • ●Parallel work that can occupy 16 vCPU
  • ●Network-heavy services — AWS rates this size at 50 Gigabit
Avoid if
  • ●The working set needs more than 128 GiB of RAM
  • ●You cannot rebuild x86-only binaries or vendor images for aarch64
  • ●GPU or FPGA acceleration is needed
  • ●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 16 vCPU would sit idle.
$1,064/mo on AWS on-demand against $15/mo on Rackspace Spot for the 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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