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I did a test performance for my server(1 ECU), but My server only arrived 1000 users in testing, how many ECU I need for 15000 users?

javier arce rodriguez
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  • The correct will be 16 ECU for 15000 users? – javier arce rodriguez Jun 02 '17 at 14:26
  • Possible duplicate of [What does ECU units, CPU core and memory mean when I launch a instance](https://stackoverflow.com/questions/19248087/what-does-ecu-units-cpu-core-and-memory-mean-when-i-launch-a-instance) – Ashan Jun 04 '17 at 03:02

1 Answers1

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The ECU (Elastic Compute Unit) was a unit of measure designed to provide a relative measure of performance between Amazon EC2 instance types. For example, an m1.small instance had 1 ECU, an m1.large had 2 ECUs, etc.

However, it is no longer possible to summarize the power of an instance in a single number. Some instances have more RAM, some have more CPUs or more powerful CPUs, GPUs, enhanced networking and even burst capabilities.

Therefore, the ECU has slowly disappeared from AWS services and documentation. It can still be viewed as an optional column in the Amazon EC2 Launch Instance console.

The ECU is definitely not a good measure of "the number of users" that a system can support. The number of users that a system can support are totally dependent upon the application architecture and its system requirements. When testing the number of users a system can support, closely monitor all system components (eg CPU load, RAM utilization, disk queues) to identify the bottleneck. You can then try to modify the application or improve the bottleneck to provide better application performance.

John Rotenstein
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    so, if we take two identical instances, say db.m5.2xlarge vs db.m4.2xlarge except that the former is one generation newer than the latter, can we assume the former is faster compared to the latter if its ECU is higher? – asgs Jul 23 '20 at 13:30
  • I would always recommending looking at [Amazon EC2 Instance Types - Amazon Web Services](https://aws.amazon.com/ec2/instance-types/) to confirm specifications. It shows both as having the same vCPUs and RAM, but lists m4 as "2.3 GHz Intel Xeon® E5-2686 v4 (Broadwell) processors or 2.4 GHz Intel Xeon® E5-2676 v3 (Haswell) processors" and m5 as "Up to 3.1 GHz Intel Xeon® Platinum 8175M processors with new Intel Advanced Vector Extension (AVX-512) instruction set". – John Rotenstein Jul 23 '20 at 21:20
  • thank you. I just checked the specs from the link you shared. so, is it possible for the m5 to provide a higher ECU because the CPU has a higher frequency compared to the other, although the processors are entirely different and may exhibit differences in other features? – asgs Jul 26 '20 at 14:54
  • Frankly, I have not seen ECU referenced for several years now, since it is now an inadequate measure due to GPUs, Intel vs AMD, networking differences, etc. The best method is to pick a family that best meets your needs (eg RAM:CPU ratio, GPU, networking, chipset), then perform tests to determine which size works best within that family. – John Rotenstein Jul 26 '20 at 21:12