The vast majority of applications don’t run run the CPU flat-out at 100% utilization continuously. Take a web application, for instance. It typically fluctuates between periods of high and low demand, but hardly ever uses a server’s compute at full capacity.
CPU utilization for many common workloads that customers run in the AWS Cloud today. (source: AWS Documentation)
One easy and cost-effective way to run such workloads is to use the Amazon EC2 M7i-flex instances which we introduced last August. These are lower-priced variants of the Amazon EC2 M7i instances offering the same next-generation specs for general purpose compute for the most popular sizes with the added benefit of giving you better price/performance if you don’t need full compute power 100 percent of the time. This makes them a great first choice if you are looking to reduce your running cost while meeting the same performance benchmarks.
This flexibility resonated really well with customers so, today, we are expanding our Flex portfolio by launching Amazon EC2 C7i-flex instances offering similar benefits of price/performance and lower costs for compute-intensive workloads. These are lower-priced variants of the Amazon EC2 C7i instances that offer a baseline level of CPU performance with the ability to scale up to the full compute performance 95% of the time.
C7i-flex instances
C7i-flex offers five of the most common sizes from large to 8xlarge, delivering 19 percent better price performance than Amazon EC2 C6i instances.
| Instance name | vCPU | Memory (GiB) | Instance storage (GB) | Network bandwidth (Gbps) | EBS bandwidth (Gbps) |
|---|---|---|---|---|---|
| c7i-flex.large | 2 | 4 | EBS-only | up to 12.5 | up to 10 |
| c7i-flex.xlarge | 4 | 8 | EBS-only | up to 12.5 | up to 10 |
| c7i-flex.2xlarge | 8 | 16 | EBS-only | up to 12.5 | up to 10 |
| c7i-flex.4xlarge | 16 | 32 | EBS-only | up to 12.5 | up to 10 |
| c7i-flex.8xlarge | 32 | 64 | EBS-only | up to 12.5 | up to 10 |
Should I use C7i-flex or C7i?
Both C7i-flex and C7i are compute-optmized instances powered by custom 4th Generation Intel Xeon Scalable processors which are only available at Amazon Web Services (AWS). They offer up to 15 percent better performance over comparable x86-based Intel processors used by other cloud providers.
They both also use DDR5 memory, feature a 2:1 ratio of memory to vCPU, and are ideal for running applications such as web and application servers, databases, caches, Apache Kafka, and Elasticsearch.
So why would you use one over the other? Here are three things to consider when deciding which one is right for you.
Usage pattern
EC2 flex instances are a great fit for when you don’t need to fully utilize all compute resources.
You can achieve 5 percent better price performance and 5 percent lower prices due to efficient use of compute resources. Typically, this is a great fit for most applications, so C7i-flex instances should be the first choice for compute-intensive workloads.
However, if your application requires continuous high CPU usage, then you should use C7i instances instead. They are likely more suitable for workloads such as batch processing, distributed analytics, high performance computing (HPC), ad serving, highly scalable multiplayer gaming, and video encoding.
Instance sizes
C7i-flex instances offer the most common sizes used by a majority of workloads going up to a maximum of 8xlarge in size.
If you need higher specs, then you should look into the large C7i instances, which include 12xlarge, 16xlarge, 24xlarge, 48xlarge and two bare metal options with metal-24xl and metal-48xl sizes.
Network bandwidth
Larger sizes also offer higher network and Amazon Elastic Block Store (Amazon EBS) bandwidths so you may need to use one of the larger C7i instances depending on your requirements. C7i-flex instances offer up to 12.5 Gbps of network bandwidth and up to 10 Gbps of Amazon Elastic Block Store (Amazon EBS) bandwidth which should be suitable for most applications.
Things to know
Regions – Visit AWS Services by Region to check whether C7i-flex instances are available in your preferred regions.
Purchasing options – C7i-Flex and C7i instances are available in On-Demand, Savings Plan, Reserved Instance, and Spot form. C7i instances are also available in Dedicated Host and Dedicated Instance form.
To learn more visit Amazon EC2 C7i and C7i-flex instances
from AWS News Blog https://aws.amazon.com/blogs/aws/new-compute-optimized-c7i-flex-amazon-ec2-flex-instances/