Instances›AWS EC2›r9g›r9g.4xlarge
Compute
vCPUs16
Memory128 GiB
Mem / vCPU8.00 GiB
ProcessorGraviton5 Processor
Clock speed3.3 GHz
Architecturearm64
Storage
TypeEBS only
Bandwidth12,000 Mbps
Throughput1500 MB/s
IOPS48,000
Networking
PerformanceUp to 17 Gigabit
Max ENIs8
IPv6Yes
GPUNone
Family sizes
r9g.medium1 vCPU · 8 GiB
r9g.large2 vCPU · 16 GiB
r9g.xlarge4 vCPU · 32 GiB
r9g.2xlarge8 vCPU · 64 GiB
r9g.4xlarge16 vCPU · 128 GiB
r9g.8xlarge32 vCPU · 256 GiB
r9g.12xlarge48 vCPU · 384 GiB
r9g.16xlarge64 vCPU · 512 GiB
r9g.24xlarge96 vCPU · 768 GiB
r9g.48xlarge192 vCPU · 1536 GiB
r9g.metal-48xl192 vCPU · 1536 GiB
r9g.4xlarge

The r9g.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, "9" is the generation, "g" marks AWS Graviton (ARM) processors and "4xlarge" is the size within the r9g family. It runs on AWS Graviton5 Processor at 3.3 GHz, and AWS introduced it in August 2026. r9g is the current generation of the r family, so there is no newer AWS size to migrate to. mh.vs1.2xlarge on Rackspace Spot lines up one-for-one: 16 vCPU and 128 GiB, $1.03/hr on AWS in US East (N. Virginia), from $0.021/hr on Rackspace Spot.

Match qualityx86 substitution

r9g.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$1.027$0.466$0.021
$1.006 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
  • ●Database instances that keep the working set in RAM
  • ●Graph and search workloads with large indexes
  • ●In-memory caches such as Redis and Memcached
  • ●Workloads that fit inside 128 GiB of RAM
  • ●Parallel work that can occupy 16 vCPU
  • ●Network-heavy services — AWS rates this size at Up to 17 Gigabit
Avoid if
  • ●The working set needs more than 128 GiB of RAM
  • ●You cannot rebuild x86-only binaries or vendor images for aarch64
  • ●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.
  • ●Local NVMe or instance-store disk is a hard requirement
  • ●GPU or FPGA acceleration is needed
r9g.4xlarge runs $750/mo on AWS on-demand. The equivalent on Rackspace Spot: $15/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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