Notes: benchmarking MongoDB with YCSB - need more RAM

Using YCSB, each record is typically 1KB by default. However this requires slightly more than 2KB storage capacity with MongoDB.

As the result, a database/collection with 1 million records/documents will occupy more than 2GB.

And when loading or operating these records 1 million times with a uniform request distribution, the RAM must be much more than 4GB.

During my test, a 6GB RAM will maintain a reasonable performance, while 4GB RAM can lead to collapsed performance, especially for scanning operations.

I used MongoDB 3.0.7 and 3.2.0 with YCSB 0.5.0.