What is a RAM cache?

Question

ubuntu

Hello. The question is, there is a simple server with 2 GB of RAM with one core, there are several new sites on WP, so I often turn on htop and leave it in the background, the RAM always takes no more than 1 GB,

but in the West the schedule is always like this

. e. after talking with other people, I realized that htop shows in numbers the value of the memory that the system is using now, but in the vest using the cache, I didn’t know this before)
After that, after reading what a memory cache is, I already imagined what it was, namely, I realized that By default, the system takes all the memory (almost) that is free to the cache, and then when it starts a new process, it gives it out of the cache, it's faster.
Having made the conclusion that in this situation I have almost 1 GB of RAM (in the cache),

I launched a simple parser on the server that takes very little memory on the local, and mysql turned off almost immediately with the start of the parser, apparently it didn’t have enough RAM (before that it was turned off precisely because of this) but why ?, it turns out I didn’t understand correctly what is an operative cache ?, or do you still need to dig towards the parser and did I understand everything correctly?
Ps I ask you not to throw stones too much for a not very smart question), I don’t understand this much, but I would like more)

Answer 1

Maybe there is an answer here.