Recently we've been having problems with swap on our postgresql server. It has 125GB of RAM. We've decided to calculate it's memory consumption. To do this we've used the formulas from the official docs [1]. However there is one parameter that seems strange - Shared disk buffers. According to the formula it occupies the following space:
(block_size + 208) * shared_buffers
Our values are
block_size=8192
shared_buffers=30GB
The block_size has the default value and shared_buffers was calculated by pgtune. According to the formula the product will be around 252 000 GB which doesn't make any sense. Is there something wrong with the formula? Or should we make our shared_buffers approx. 10 000 times lower? :)