It's not really something that can be easily calculated based on write rate, but more something you have to find empirically and adjust periodically. Generally speaking, I'd start by running "nodetool gcstats" or similar and just see what the GC pause stats look like. If it's not pausing much or for long, you're good. If it is, you'll likely need to do some tuning based on GC logging which may involve increasing the heap but could also mean decreasing it or changing the collection strategy.
Generally speaking, with G1GC you can get away with just setting a larger heap than you really need and it's close enough to optimal. CMS is theoretically more efficient, but far more complex to get tuned properly and tends to fail more dramatically. On Mon, May 20, 2019 at 7:38 AM Akshay Bhardwaj < akshay.bhardwaj1...@gmail.com> wrote: > Hi Experts, > > I have a 5 node cluster with 8 core CPU and 32 GiB RAM > > If I have a write TPS of 5K/s and read TPS of 8K/s, I want to know what is > the optimal heap size configuration for each cassandra node. > > Currently, the heap size is set at 8GB. How can I know if cassandra > requires more or less heap memory? > > Akshay Bhardwaj > +91-97111-33849 >
