How to decide Solr cloud shard per node?

Question

We have 16 64 GB RAM, 4 core machines. The index size is around 200 GB. Initially we decided to have 64 shards, ie 4 shards per node. We came to 4 shards per nodes because we have 4 core machine (4 core can process 4 shards at a time). When we tested qtime of the query was pretty high. We re-ran performance test on reduced shards. One for 32 total shards(2shards per node) and 16 total shards(1shard per node). The qtime has gone down drastically(by upto 90%) for 16 shards . So How is shards per nodes decided? Is there a formula based on machine config and index volume?

Answer 1

One other thing you will want to review is the type and volume of queries you are sending to Solr. There is no single magic formula that you can use, my best advice would be to just test a few different alternatives to see which one performs the best.

One thing to keep in mind is the JVM size and index size per server. I think it'd be nice if you could cache the entire index in memory on each box.

Additionally, make sure you are testing query response time with the queries you will actually be running, not just made up things. Things like grouping and faceting will make a huge difference.