MongoDB understands MMS graphics

Question

I'm really new to mongo,

I need to track a mongodb instance during tests using its system. I have problems understanding the diagrams provided by the MMS agent. Here are my questions:

1 - I'm worried about performance and availability, whose diagrams should I focus on?

2 - On the opcounters chart, they say: "The number of commands executed per unit of time." What is the unit of time? Also in the same diagram, what is the difference between a “team” and a “query”? What is the "getmore"?

I think there are enough questions to start with, maybe more suitable after the answers :)

Regards, Robin

Answer 1

• For performance, I suggest looking at opcounters, block%, page errors, btree and queues. For accessibility (I assume you have a set of replicas since you mention accessibility) keep an eye on replica schedules and repl lag. In no case should this list be exhaustive, but simply as an initial link in diagnosing performance problems.

• In units of time: this is the time per second if this is what is highlighted at the top of the page. Commands differ from requests (obtaining server statistics, initializing a set of replicas, and performing tasks to reduce the scale — all this is done by executing a command). When you repeat the cursor and get to the end of the returned batch, if there are more results, cursor.next () will perform the getmore operation to get the next batch.