How do I decide or evaluate the system/memory requirements for Logstash

If I want to use logstash to collect logs in from server how to decide how much memory and disk space will be required for it?

If you have any helpful links that are also welcome.

You test it and see. Personally I generally run logstash with a 400 MB heap. I know some folks will give it 4 or even 8 GB.

If you are configuring http_static loaders that load hundreds of megabytes or even gigabytes of database records into cache then you will need the memory to hold that. If you are just grokking fields out of web server logs, not so much.

Disk space will basically be the installed application code and the log files. Are you keeping the logstash logs for a week or a year? One will use 50 times as much space as the other. Then there are cases (a file input scanning a million files) where a sincedb might be a noticeable size.

Thanks!!