Instances›AWS EC2›r8i-flex›r8i-flex.4xlarge
Compute
vCPUs16
Memory128 GiB
Mem / vCPU8.00 GiB
ProcessorXeon Scalable
Clock speed3.9 GHz
Architecturex86_64
Storage
TypeEBS only
Bandwidth10,000 Mbps
Throughput1250 MB/s
IOPS40,000
Networking
PerformanceUp to 15 Gigabit
Max ENIs8
IPv6Yes
GPUNone
Family sizes
r8i-flex.large2 vCPU · 16 GiB
r8i-flex.xlarge4 vCPU · 32 GiB
r8i-flex.2xlarge8 vCPU · 64 GiB
r8i-flex.4xlarge16 vCPU · 128 GiB
r8i-flex.8xlarge32 vCPU · 256 GiB
r8i-flex.12xlarge48 vCPU · 384 GiB
r8i-flex.16xlarge64 vCPU · 512 GiB
r8i-flex.4xlarge

r8i-flex.4xlarge is AWS's memory-optimized EC2 size at 16 vCPU and 128 GiB. It runs on Intel Xeon Scalable (Granite Rapids) at 3.9 GHz, and AWS introduced it in August 2025. On Rackspace Spot the same shape is mh.vs1.2xlarge — 16 vCPU, 128 GiB, matched on both dimensions, $1.06/hr on AWS in US East (N. Virginia), from $0.021/hr on Rackspace Spot.

Pricing by region
1 hr
RegionAWS on-demandAWS Spot1-yr Reserved3-yr ReservedRackspace SpotYou save
US East, N. Virginia$1.056$0.335$0.021
$1.035 savings
US Central, Chicagono AWS region$0.021
US Central, Dallasno AWS region$0.131
Hong Kong$0.021
Sydney, Australia$1.265$0.375$0.021
$1.244 savings
London, UK$1.240$0.328$0.131
$1.109 savings
US West, San Jose$1.173$0.234$0.002
$1.171 savings
US Central, Dallas 2no AWS region$0.242
When to use it
Good for
  • ●OLAP and business intelligence query engines
  • ●Real-time analytics over hot datasets
  • ●Database instances that keep the working set in RAM
  • ●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 15 Gigabit
Avoid if
  • ●The working set needs more than 128 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 16 vCPU would sit idle.
  • ●Local NVMe or instance-store disk is a hard requirement
  • ●GPU or FPGA acceleration is needed
Stop overpaying AWS. This compute costs $771/mo on AWS vs $15/mo on Rackspace Spot.
  • 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.
Build your Cloudspace
Frequently asked questions