What is the difference between scylla read path and cassandra read path?

Question

What is the difference between Scylla read path and Cassandra read path? When I stress Cassandra and Scylla then Scylla read performance poor by 5 times than Cassandra using

Answer 1

There can be various reasons why you are not getting the most out of your Scylla Cluster.

1. Number of concurrent connections from your clients/loaders is not high enough, or you're not using sufficient amount of loaders. In such case, some shards will be doing all the work, while others will be mostly idle. You want to keep your parallelism high.

2. Scylla likes have a minimum of 2 connections per shard (you can see the number of shards in /etc/scylla.d/cpuset.conf)

3. What's the size of your dataset? Are you reading a large amount of partitions or just a few? You might be hitting a hot partition situation

I strongly recommend reading the following docs that will provide you more insights:

• https://www.scylladb.com/2019/03/27/best-practices-for-scylla-applications/

• https://docs.scylladb.com/operating-scylla/benchmarking-scylla/