Instances›AWS EC2›u-6tb1›u-6tb1.56xlarge
Compute
vCPUs224
Memory6144 GiB
Mem / vCPU27.43 GiB
ProcessorXeon Scalable
Clock speed2.1 GHz
Architecturex86_64
Storage
TypeEBS only
Bandwidth38,000 Mbps
Throughput4750 MB/s
IOPS160,000
Networking
Performance100 Gigabit
Max ENIs15
IPv6Yes
GPUNone
Family sizes
u-6tb1.56xlarge224 vCPU · 6144 GiB
u-6tb1.112xlarge448 vCPU · 6144 GiB
u-6tb1.metal448 vCPU · 6144 GiB
u-6tb1.56xlarge

u-6tb1.56xlarge is AWS's memory-optimized EC2 size at 224 vCPU and 6144 GiB. It runs on Intel Xeon Scalable (Skylake) at 2.1 GHz, and AWS introduced it in May 2021. Spot's largest VM is 16 vCPU and 128 GiB, so matching this instance would take 44 × 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-6tb1.56xlarge is 224 vCPU and 6,144 GiB. The largest comparable Spot node is mh.vs1.2xlarge at 16 vCPU and 128 GiB, so matching it would take 44 of them. That maths works out, but 44 nodes is a redesign rather than a migration — a single block of 6,144 GiB does not survive being split across a network.

If you chose u-6tb1.56xlarge because the work genuinely needs 224 cores and 6,144 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$46.404$28.596$14.910$0.924
$45.480 savings
US Central, Chicagono AWS region$0.924
US Central, Dallasno AWS region$5.764
Hong Kong$0.924
Sydney, Australia$55.611$34.270$17.868$0.924
$54.687 savings
London, UK$54.506$33.589$17.513$5.764
$48.742 savings
US West, San Jose$0.088
US Central, Dallas 2no AWS region$10.648
When to use it
Good for
  • ●In-memory caches such as Redis and Memcached
  • ●Large JVM heaps and application servers that hold state
  • ●OLAP and business intelligence query engines
  • ●Workloads that fit inside 6144 GiB of RAM
  • ●Parallel work that can occupy 224 vCPU
  • ●Network-heavy services — AWS rates this size at 100 Gigabit
Avoid if
  • ●The working set needs more than 6144 GiB of RAM
  • ●You want a single-machine Spot equivalent. At this size there is not one.
  • ●CPU-bound work. You are paying for memory this workload will not use.
  • ●More than 27.43 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
u-6tb1.56xlarge is $33,875/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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