Es nodes configuration

Elastic Stack Elasticsearch
1

Hi Team,
Currently, in our cluster, this is the configuration,
Nodes - 7 nodes(3master, 4datanodes, write happens 1 month once, so mostly read cluster)
ES - 6.4
Memory - 128 GB(ES - 32 GB)
Cores - 16
Shards - 130+ (each shard 30-40 GB)
Indices - 5

During peak hours we're getting search rejections due to the QPS, so we're planning to add more nodes to the cluster. W.r.t shall we divide our current cluster nodes from (128GB, 16C) to (64GB, 8C) & still 32 GB will be allocated to ES, does this help in more parallelism in processing requests?

Which is better out of these two, less nodes with more memory & CPU vs more nodes with less memory & CPU for Search processing from a scalability perspective?

2

From a scalability perspective the best thing to do is upgrade to a version that isn't EOL. There have been many performance improvements in the 3 years since 6.4 was released.

Other than that you probably need to run benchmarks to find the difference. 4 data nodes and a total of 4×(128-32)=384GB of pagecache might well perform better than 8 data nodes and a total of 8×(64-32)=256GB of pagecache.

3

Thanks, David for your reply and w.r.t version, yes David, we're planning to upgrade our cluster to 7.x in coming months.