cache.t3.medium (Amazon ElastiCache Instance Overview)

Use Cases for cache.t3.medium

Primary Use Cases

• Burst Capacity for Periodic Spikes: cache.t3.medium is ideal for workloads that experience intermittent spikes in CPU demand but don’t need consistently high CPU consumption. This makes it a great fit for applications handling web content caching, API response caching, and user session management.

• Development and Staging Environments: cache.t3.medium is well suited for development and QA environments where cost savings are prioritized but testing workloads occasionally need bursts of CPU performance.

• Low to Moderate Traffic Caching Applications: Applications that don’t need dedicated infrastructure for intensive computational use or where the majority of data lookups are simple, can easily be handled by cache.t3.medium, with the ability to burst for larger blocks of cache retrievals during traffic peaks.

When to Use cache.t3.medium

The cache.t3.medium instance is especially useful when:

• Your Workload Exhibits Variability: When your application’s CPU requirement fluctuates, cache.t3.medium offers an optimal mix of cost-effectiveness and intermittent burst performance.
• You Need Cost-Effective Caching: If you're looking for a low-cost solution to cache transient or non-persistent session data, this instance type aligns with your goals.
• You're Working in DevOps Stages: Environments reserved for testing, prototyping, or development can efficiently use this tier to avoid paying for higher upfront compute needs, while still giving enough resources to support varied test workloads.

When Not to Use cache.t3.medium

• Low Latency or Consistent High Performance Needed: If you require consistently high CPU or very low-latency responses regardless of the workload (especially in production environments), the t3.medium might not provide enough guaranteed capacity. In such cases, opting for compute-optimized instances like cache.c5.large or cache.m5.large would be a better option.

• Heavy, Compute-Intensive Applications: If your application involves continuous compute-intensive tasks (e.g., large-scale real-time data analysis or high-frequency trading), the t3.medium’s burstable nature might fall short. In this case, consider compute-optimized series or memory-optimized series (like cache.r5.large) for significantly higher compute and memory capacity.

• Memory-Intensive Workloads: If your application is memory-bound, opting for memory-optimized instances with more substantial memory resources (e.g., r-series like cache.r6g.large) would be more appropriate, as they offer higher memory-to-vCPU ratios and greater throughput.

Understanding the t3 Series

Overview of the Series

The t3 series is part of Amazon ElastiCache’s burstable general-purpose instance types. It is built to provide a balanced mix of compute, memory, and network resources for applications with variable CPU usage. The key feature of the t3 series is its ability to handle sporadically intensive workloads by using CPU credits. This makes it highly cost-effective for workloads that don’t require consistent access to high levels of CPU.

The economy of the t3 series allows users to lower costs when running less intensive applications while still maintaining the ability to burst performance when needed. This series is ideal for many general-purpose cache workloads that exhibit periodic CPU load spikes.

Key Improvements Over Previous Generations

The t3 series introduces several improvements compared to the earlier t2 series:

• Enhanced CPU Performance: The t3 series leverages newer Intel Xeon processors and is built on the AWS Nitro System, enabling better and more efficient CPU utilization.
• More Efficient CPU Credit System: One key advancement lies in the optimized CPU credit system, resulting in smoother state transitions between baseline and burst states.
• More Memory in Similar Classes: Across the t3 series, including the cache.t3.medium instance, memory allocations have been increased compared to the comparable t2 instances.

Comparative Analysis

Primary Comparison

• Compared to the now-deprecated t2 generation, the t3 generation offers better baseline performance with more flexibility in bursting CPU utilization. In addition, the Nitro architecture provides better overall throughput and security compared to traditional hypervisors.

Brief Comparison with Relevant Series

• General-purpose series (e.g., m-series): If you need more consistent CPU power and higher memory-to-vCPU ratios for your cache workloads, the m-series (e.g., cache.m5.large) could be a more suitable option. This series is better suited for continuously running processes where burst capabilities aren't the optimal choice.

• Compute-optimized series (e.g., c-series): For compute-heavy workloads, such as those involving intensive data processing or mathematical computations, consider the compute-optimized c-series (e.g., cache.c5.large). This series often performs better in CPU-restricted environments than the burstable t-series.

• Cost-effective burstable performance (e.g., t-series): Burst-focused instances like t3 give you excellent cost efficiency if your workloads exhibit short spikes of high demand followed by periods of low or idle resource use. It’s a good cost-saving mechanism compared to general-purpose or compute-optimized instances.

• High Network Bandwidth Series: If your workload requires extremely high throughput, consider instances with higher network performance, such as the r6g or r5 series, both of which offer better memory-to-vCPU ratio and network bandwidth than the t3 series.

Migration and Compatibility

Migrating to the t3 series from earlier t-series (e.g., t2) is relatively seamless since both generations leverage the same architecture for typical Redis and Memcached applications in ElastiCache. Keep in mind the following tips:

• Check your CPU Credit Requirements: Depending on your workload’s intensity, managing CPU credits will be important to ensure cost-effectiveness. You could enable unlimited bursting in case your application demands higher CPU usage over longer periods.
• Check Network and Memory Needs: While t3 instances can handle most caching workloads, ensure your workload wouldn’t benefit from moving to a higher memory or high-network-performance series if you're considering a long-term migration strategy.