AWS EBS IOPS, what happens when it gets exceeded

Question

Assuming I have a gp3 SSD backed EBS with 3000 IOPS with block size of 256kb & througput of 128Mbps ( EBS is not optimized )

What happens to my IO requests if I exceed the 3000 IOPS request? Do they stall? Or is that more of a function of throughput?

Let's take an example

An application does 3000 random IO (so no chance of merging) of 1kb size per second. This means I will be hitting the IOPS limit but throughput is only 3Mbps. Will this cause my further IO operations to stall?

Is it preferable to increase my IO size in that case?

Answer 1

EBS will throttle your I/O in this case and you will not see more than 3000 IOPS. In general, they have throttling at EBS volume level and at EC2 instance level (max/baseline EBS IOPS of EC2 instance type, limit across all attached EBS volumes). You will be throttled as soon as you hit any of those limits.