Instances›AWS EC2›u-3tb1›u-3tb1.56xlarge
Compute
vCPUs224
Memory3072 GiB
Mem / vCPU13.71 GiB
ProcessorXeon Scalable
Clock speed2.1 GHz
Architecturex86_64
Storage
TypeEBS only
Bandwidth19,000 Mbps
Throughput2375 MB/s
IOPS80,000
Networking
Performance50 Gigabit
Max ENIs8
IPv6Yes
GPUNone
Family sizes
u-3tb1.56xlarge224 vCPU · 3072 GiB
u-3tb1.56xlarge

The u-3tb1.56xlarge is a memory-optimized AWS EC2 instance: 224 vCPU and 3072 GiB of memory, 13.71 GiB per vCPU. It runs on Intel Xeon Scalable (Skylake) at 2.1 GHz, and AWS introduced it in August 2022. Spot's largest VM is 16 vCPU and 128 GiB, so matching this instance would take 22 × mh.vs1.2xlarge — arithmetically true and operationally absurd. The Spot column below prices that whole fleet, so read it as a scale reference rather than a drop-in replacement: at this size the useful question is what a shard of the workload costs, which is $0.021/hr per node.

Match qualityNo single-node equivalent

u-3tb1.56xlarge is 224 vCPU and 3,072 GiB. The largest comparable Spot node is mh.vs1.2xlarge at 16 vCPU and 128 GiB, so matching it would take 22 of them. That maths works out, but 22 nodes is a redesign rather than a migration — a single block of 3,072 GiB does not survive being split across a network.

If you chose u-3tb1.56xlarge because the work genuinely needs 224 cores and 3,072 GiB together — an in-memory database, a large analytics engine, a single big solver — Rackspace Spot has no equivalent. What does fit is everything around it: the application servers, batch workers and CI that talk to that machine, which is usually the larger share of the bill.

Pricing by region
1 hr
RegionAWS on-demandAWS Spot1-yr Reserved3-yr ReservedRackspace SpotYou save
US East, N. Virginia$27.300$16.823$8.771$0.462
$26.838 savings
US Central, Chicagono AWS region$0.462
US Central, Dallasno AWS region$2.882
Hong Kong$36.227$22.325$11.640$0.462
$35.765 savings
Sydney, Australia$32.715$20.160$10.511$0.462
$32.253 savings
London, UK$2.882
US West, San Jose$0.044
US Central, Dallas 2no AWS region$5.324
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 3072 GiB of RAM
  • ●Parallel work that can occupy 224 vCPU
  • ●Network-heavy services — AWS rates this size at 50 Gigabit
Avoid if
  • ●The working set needs more than 3072 GiB of RAM
  • ●You want a single-machine Spot equivalent. At this size there is not one.
  • ●More than 13.71 GiB of RAM per vCPU is needed — that ratio is fixed for the whole family
  • ●The work is single-threaded. Most of these 224 vCPU would sit idle.
  • ●Local NVMe or instance-store disk is a hard requirement
  • ●GPU or FPGA acceleration is needed
u-3tb1.56xlarge is $19,929/mo on AWS on-demand. A mh.vs1.2xlarge node on Rackspace Spot is $15/mo — at this size the per-node price is the honest comparison.
  • 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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