Instances›AWS EC2›r5b›r5b.16xlarge
Compute
vCPUs64
Memory512 GiB
Mem / vCPU8.00 GiB
ProcessorXeon Platinum 8259
Clock speed3.1 GHz
Architecturex86_64
Storage
TypeEBS only
Bandwidth40,000 Mbps
Throughput5000 MB/s
IOPS173,333
Networking
Performance20 Gigabit
Max ENIs15
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.16xlarge

The r5b.16xlarge pairs 64 vCPU with 512 GiB of RAM, the 8.00 GiB-per-vCPU ratio that marks a memory-optimized instance. In the name, "r" stands for RAM, "5" is the generation, "b" marks block-storage optimisation and "16xlarge" 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.16xlarge is the direct replacement at this size. Spot's node ladder tops out below this size, so r5b.16xlarge becomes 4 × mh.vs1.2xlarge (64 vCPU, 512 GiB combined), $4.77/hr on AWS in US East (N. Virginia), from $0.084/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.16xlarge gives you 64 vCPU and 512 GiB in a single machine. The largest comparable Spot node, mh.vs1.2xlarge, is 16 vCPU and 128 GiB, so the equivalent here is 4 nodes rather than one.

Spot runs as managed Kubernetes, so a 4-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 64 cores and 512 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$4.768$1.693$3.004$1.931$0.084
$4.684 savings
US Central, Chicagono AWS region$0.084
US Central, Dallasno AWS region$0.524
Hong Kong$0.084
Sydney, Australia$5.792$2.146$3.649$2.346$0.084
$5.708 savings
London, UK$5.600$2.214$3.545$2.367$0.524
$5.076 savings
US West, San Jose$0.008
US Central, Dallas 2no AWS region$0.968
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 512 GiB of RAM
  • ●Parallel work that can occupy 64 vCPU
  • ●Network-heavy services — AWS rates this size at 20 Gigabit
  • ●Anything that shards cleanly across 4 nodes, which is how it maps onto Rackspace Spot
Avoid if
  • ●Starting a new deployment. r6i.16xlarge is the newer generation at this size.
  • ●The working set needs more than 512 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 64 vCPU would sit idle.
  • ●Local NVMe or instance-store disk is a hard requirement
Stop overpaying AWS. This compute costs $3,481/mo on AWS vs $61/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.
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