Is there any explanation somewhere about the exact memory usage of all couchbase processes?
Let me give an example:
- cluster with 3 nodes, 3.7 GB RAM per node
- per-server RAM quota set to 2000 MB
- couchbase web interface shows “memory used as measured from mem_used”: 1.04 GB
- memory consumed by beam.smp process, according to PS command: 27% (~1020 MB), seems consistent with value showed by web interface
- memory consumed by memcached process, according to PS command: 43.8% (~1620MB).
So, generally, I have noted some inconsistent data:
- beam.smp + memcached consume together more memory than set in per-server ram quota
- the memory used reported by couchbase does not include memory used by memcached
Now some questions:
- what exactly is the memcached process? Does it cache keys / values? What is the purpose of memory used in beam.smp vs memory used by memcached process?
- is there any way to control memcached process memory usage?
- does memcached process “scale” automatically memory usage, to use free memory for caching, or how it allocates memory?
I’m asking, because our machines are getting very close to 100% memory usage. We have limited, what we think is couchbase memory usage - but the total memory consumption didin’t change.