Scylla Summit 2017: How to Optimize and Reduce Inter-DC Network Traffic and Stop Paying too Much!

In this presentation, I'll speak of the benefits of running Scylla on our Big Data environment which stores over 500TB of data as well as using Scylla as the indexing engine to replace MongoDB and Cassandra for our log data analysis platform.

I will be giving a talk about performance characterization and tuning of Scylla on Samsung NVMe SSDs. We will characterize the performance of Scylla on Samsung high-performance NVMe SSDs and show how Z-SSD ─ the Samsung ultra-low-latency NVMe drive ─ can significantly shrink the performance gap between in-memory and in-storage with Scylla. We will further evaluate the throughput-vs-latency profile of Scylla with NVMe devices and present end-to-end latencies (from the client's viewpoint) as well as the latencies of the software/hardware stack. We will show that a Z-SSD-backed Scylla cluster can provide competitive performance to an in-memory deployment while sharply reducing costs.

Scylla's monitoring capability has come a long way in the last year. We now have native support for Prometheus. Through scylla-grafana-monitoring, we have started providing default dashboards summarizing the most important aspects of Scylla for users. In this talk, I will cover what is currently available in our metrics, other non-standard metrics that are interesting but not available in our main dashboard, as well as our future plans for enhancement.

This presentation discusses the "cold node problem" that occurs when a node restarts in a Cassandra cluster. When a node restarts, it loses its cached data and becomes a bottleneck. The presentation proposes a "heat weighted load balancing" solution where the cluster tracks each node's cache hit ratio and redistributes requests based on this ratio after a restart. Testing shows this solution significantly improves throughput after a node restart by distributing requests more evenly across nodes based on their "heat" or cache contents.

In my talk, I will present the different compaction strategies that Scylla provides, and demonstrate when it is appropriate and when it is inappropriate to use each one. I will then present a new compaction strategy that we designed as a lesson from the existing compaction strategies by picking the best features of the existing strategies while avoiding their problems.

Zenly (recently acquired by Snap) makes a social map app. Their team has been running Scylla in production for the past eight months. Get an overview of the reasons they chose Scylla, its deployment on Google Cloud, the performances they achieved, plus learn as they share some of the few hiccups they hit along the way.

In this talk, we will share useful tools and techniques that we are using in the field to understand Scylla clusters. Users will learn how to use those same tools to better understand their deployment. Some of the questions that will be answered are: - how to find out which queries are the slowest and why - how we go about understanding the impact of the data model in a node's performance - how to check which resources are the bottlenecks in the cluster

Shlomi Livne, VP of R&D at ScyllaDB, presented on the performance benefits of using user-defined types (UDTs) in ScyllaDB. He explained that with traditional columns, each column has overhead and flexibility comes at a price. However, with frozen UDTs, the columns are treated as a single unit, sharing metadata and improving performance. Livne showed results of a test where UDTs with many fields outperformed traditional columns with the same number of fields. However, he noted that Scylla's row cache and Java driver performance need improvement for UDTs.

Are you a MySQL DBA or DevOps individual being asked to run Cassandra or Scylla? Feeling overwhelmed? In this talk, I will present Cassandra/Scylla operations in terms that directly relate to MySQL. I will show you comparisons between the Information Schema and the Cassandra/Scylla System keyspace(s). I will also talk about metrics available in MySQL versus Cassandra/Scylla and how to retrieve them. Finally, I will talk about how MySQL replication compares with Cassandra replication. Hopefully, when I am done you will be able to relate to Cassandra operations in a practical and useful way.