ECU

AWS Cassandra 2025: Cassandra 5.0, NUMA, and Graviton4 Performance Guide

What’s New in 2025

Key Updates and Changes

• Graviton4 Processors: Up to 40% faster than Graviton3 for databases, 192 cores at 2.8 GHz
• NUMA Evolution: Two-socket NUMA memory clustering on Graviton4 for improved performance
• Cassandra 5.0: Enhanced NUMA awareness with improved memory management
• Instance Types: New R8g, X8g, C8g, M8g, I8g instances with better NUMA support
• Performance Gains: 30-40% improvement over x86 for Cassandra workloads

Major Architecture Changes

• Single NUMA Domain: Graviton3 maintains single NUMA domain simplicity
• Dual NUMA Support: Graviton4 introduces two-socket NUMA clustering
• Memory Bandwidth: Improved memory controller performance across generations
• Core Density: Up to 192 physical cores per instance (R8g.48xlarge)
• ARM Optimization: Better Java performance on ARM architecture

AWS Cassandra 2025 and NUMA Architecture

In 2025, AWS has significantly evolved its NUMA (Non-Uniform Memory Access) support with Graviton4 processors. Understanding NUMA is crucial for optimizing Cassandra 5.0 performance on modern EC2 instances.

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Cassandra 5.0 AWS CPU Requirements: Graviton4, ZGC, and Performance Optimization

What’s New in 2025

Key Updates and Changes

• Cassandra 5.0: Enhanced CPU utilization with improved compaction and streaming
• Graviton4 Processors: 40% better performance for database workloads
• ZGC Integration: Low-latency garbage collection for improved response times
• Instance Types: New I8g, R8g, C8g families optimized for Cassandra workloads
• Compaction Improvements: Better concurrent compactor defaults and tuning

Major Performance Enhancements

• Unified Compaction: Reduced CPU overhead in Cassandra 5.0
• Vector Search: CPU-intensive operations requiring additional cores
• Streaming Performance: Improved parallel processing for data migration
• Memory Management: Better allocation strategies reducing CPU pressure
• ARM Optimization: Native ARM64 support for Graviton processors

Cassandra 5.0 CPU Requirements in AWS Cloud

Cassandra 5.0 is highly concurrent and can utilize as many CPU cores as available when configured correctly. Understanding CPU requirements is crucial for optimal performance on AWS EC2 instances.

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AWS Cassandra: Cassandra, NUMA and EC2

AWS Cassandra and NUMA

The i3.8xlarge, c4.8xlarge, m4.10xlarge, and above EC2 instance types use more than 1 CPU, which means NUMA controls are available.

A good read on this is from Al Tolbert’s blog post.

The quickest way to tell if a machine is NUMA is to run “numactl –hardware”. -Al Tobey blog post on Cassandra tuning

NUMA stands for Non-Uniform Memory Architecture. Modern x86 CPUs contain an integrated memory controller. Multi-socket system, have two memory controllers. Each CPU gets a share of the memory. If one CPU socket needs memory that another CPU socket has, the memory is transferred. Transferring this memory between CPUs is more expensive than if the memory only existed in one CPUs memory. When a JVM thread only uses memory local to one CPU, things go fast, and if not slower (10 CPU cycles vs. 100 or some order of magnitude).

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Cassandra AWS CPU Guidelines

Cassandra CPU requirements in AWS Cloud

Cassandra is highly concurrent. Cassandra nodes can uses as many CPU cores as available if configured correctly.

What are vCPUs and ECUs?

An Amazon EC2 vCPU is a hyper thread, often referred to as a virtual core. Think of it as a physical thread of execution. It is able to run one thread at a time (which of course could be swapped out).

An Amazon ECU is some made up term that AWS used to use which was the power of the Intel Pentium chip that they used on the earliest incarnations of EC2. 50 ECU would be like 50 Pentium chips from a bygone era. Ignore ECUs.

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