Instances›AWS EC2›r5b›r5b.8xlarge
Compute
vCPUs32
Memory256 GiB
Mem / vCPU8.00 GiB
ProcessorXeon Platinum 8259
Clock speed3.1 GHz
Architecturex86_64
Storage
TypeEBS only
Bandwidth20,000 Mbps
Throughput2500 MB/s
IOPS86,667
Networking
Performance10 Gigabit
Max ENIs8
IPv6Yes
GPUNone
Family sizes
r5b.large2 vCPU · 16 GiB
r5b.xlarge4 vCPU · 32 GiB
r5b.2xlarge8 vCPU · 64 GiB
r5b.4xlarge16 vCPU · 128 GiB
r5b.8xlarge32 vCPU · 256 GiB
r5b.12xlarge48 vCPU · 384 GiB
r5b.16xlarge64 vCPU · 512 GiB
r5b.24xlarge96 vCPU · 768 GiB
r5b.metal96 vCPU · 768 GiB
r5b.8xlarge

r5b.8xlarge is AWS's memory-optimized EC2 size at 32 vCPU and 256 GiB. In the name, "r" stands for RAM, "5" is the generation, "b" marks block-storage optimisation and "8xlarge" is the size within the r5b family. It runs on Intel Xeon Platinum 8259 (Cascade Lake) at 3.1 GHz, and AWS introduced it in December 2020. AWS has since shipped r6i, r7i, r8i and r9g; r6i.8xlarge is the direct replacement at this size. The closest Spot shape is mh.vs1.2xlarge at 16 vCPU, so this instance maps to 2 of them — 32 vCPU and 256 GiB across the fleet, $2.38/hr on AWS in US East (N. Virginia), from $0.042/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

r5b.8xlarge gives you 32 vCPU and 256 GiB in a single machine. The largest comparable Spot node, mh.vs1.2xlarge, is 16 vCPU and 128 GiB, so the equivalent here is 2 nodes rather than one.

Spot runs as managed Kubernetes, so a 2-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 32 cores and 256 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$2.384$0.873$1.502$0.966$0.042
$2.342 savings
US Central, Chicagono AWS region$0.042
US Central, Dallasno AWS region$0.262
Hong Kong$0.042
Sydney, Australia$2.896$0.970$1.825$1.173$0.042
$2.854 savings
London, UK$2.800$0.816$1.772$1.184$0.262
$2.538 savings
US West, San Jose$0.004
US Central, Dallas 2no AWS region$0.484
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 256 GiB of RAM
  • ●Parallel work that can occupy 32 vCPU
  • ●Network-heavy services — AWS rates this size at 10 Gigabit
  • ●Anything that shards cleanly across 2 nodes, which is how it maps onto Rackspace Spot
Avoid if
  • ●Starting a new deployment. r6i.8xlarge is the newer generation at this size.
  • ●The working set needs more than 256 GiB of RAM
  • ●Local NVMe or instance-store disk is a hard requirement
  • ●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
$1,740/mo on AWS on-demand against $31/mo on Rackspace Spot for the 2-node 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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