Cassandra tuning for Request timed out

问题:

I am using Apache Cassandra as a data store for one of my project, It is a single node and running smoothly for 4 to 5 hours then I started getting the Request timed out error.

I observed the following in the last week and tuned all

1) GC pause was taking a long time and I tuned the GC pause and currently it is not even taking 2 seconds.

PF the GC logs for reference : https://files.fm/u/h8b2mnwm#_

2) Memory is not even using above 5GB of 8GB allocated
3) CPU with 8 cores seems fine.

If everything seems proper, What is the next thing I need to look in Cassandra to solve the Request timed out.

NOTE :
i) READ / WRITE timeout is 60 seconds.
ii) Single Write with partition key gives Request timed out