What is the recommended value of file descriptors for Kafka?

[#1]

Summary

As Kafka works with many log segment files and network connections, the Maximum Process File Descriptors setting may need to be increased in some cases in production deployments, if a broker hosts many partitions

Warnings observed

Concerning : Open file descriptors: 18,646. File descriptor limit: 32,768. 
Percentage in use: 56.90%. Warning threshold: 50.00%.

In case of such open file descriptor warnings in Kafka for CDP, you need to increase file descriptors in Kafka cluster. As per the guide [1], below formula is used

(number of partitions)*(partition size / segment size)

Details about these parameters are as follows:

a. Number of partitions > it can be seen if you go to SMM and brokers tab. Alternatively, you can simply perform a file count of the kafka data directory. You can find this directory in CM > Kafka > log.dirs
b. Partition size > it is the size of log.dirs directory, you can check the disk usage of log.dirs using du -sh command to find this size.
c. Segment size > it can be found by going to CM > Kafka > Segment File Size

Additionally, a simple alternate method of calculation can be to simply search for the number of files in Kafka data directory and set the file descriptors to 2-3 times the value.

[1] File descriptor limits