MongoDB total memory usage is abnormal

Yanfei_Wu · 2024-05-31T09:50:59.056Z

I deployed a v5.0.10 replica set in K8S using the bitnami helm template.

The Pod memory limit is 32G, and the current memory usage is 90%.

I checked MongoDB and found that wiredTiger.cache currently uses less than 9G. I don’t understand why the total memory is used so much?

“bytes currently in the cache” : NumberLong(“922120l585”)
“maximum bytes configured” : NumberLong(“15032385536”)

Aasawari · 2024-05-31T11:41:25.450Z

Hi @Yanfei_Wu and welcome to the community forum

There could be different reasons for the cache occupying the large space.

There could be a lot of open connections from the application end which would take up the memory space.
There could a lot of Indexes or read and write operations on the replica sets.

To help you further, could you help me with the output for the db.serverStatus() for the replica set?
This would help the community with more information to assist you further.

Regards
Aasawari

Yanfei_Wu · 2024-06-03T02:47:35.042Z

Hello @Aasawari , the output of db.serverStatus() is too extensive.
Which parameters or metrics do you generally need for reference?