If the IOPS is 16000 can that be interpreted as 16000 parallel reads/writes? 8000 reads 8000 writes or 16000 reads 0 writes?
I don’t think that it means that you will have half the IOPS dedicated to read and the other half write operations. The 16000 IOPS means that you can have concurrent read write operations that reach a maximum of 16k IOPS operations, hence the name Input/Output Operations per second which is measured in KiB (Kibibytes, 1KiB = 1024 Bytes) and 1 I/O operation = 256 KiB.
This was interesting to research Link: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ebs-io-characteristics.html