Poor performance on ssd raid1 for 200M documents
I'm trying to benchmark the couchbase on 4 nodes cluster with 4 ssd(120GB full capacity) raid 1, 32GB RAM per node on 200M (100 bytes 10 fields) documents in the cluster by YCSB(8 clients with 32 threads, 50 read/50 update).The RAM limit is 80%.
I get an excellent performance result for 50M documents - 600K ops/sec however on the same settings I got only ~30K ops/sec for 200M documents.
What kind of settings should I tune up to get a comparable throughput?
Thank you in advance.