Maximizing Performance of AWS RDS for MySQL with Dedicated Log Volumes

A quick configuration change may do the trick in improving the performance of your AWS RDS for MySQL instance. Here, we will discuss a notable new feature in Amazon RDS, the Dedicated Log Volume (DLV), that has been introduced to boost database performance. While this discussion primarily targets MySQL instances, the principles are also relevant to PostgreSQL and MariaDB instances.

What is a Dedicated Log Volume (DLV)?

A Dedicated Log Volume (DLV) is a specialized storage volume designed to house database transaction logs separately from the volume containing the database tables. This separation aims to streamline transaction write logging, improving efficiency and consistency. DLVs are particularly advantageous for databases with large allocated storage, high I/O per second (IOPS) requirements, or latency-sensitive workloads.

Who can benefit from DLV?

DLVs are currently supported for Provisioned IOPS (PIOPS) storage, with a fixed size of 1,000 GiB and 3,000 Provisioned IOPS. Amazon RDS extends support for DLVs across various database engines:

• MariaDB: 10.6.7 and later v10 versions
• MySQL: 8.0.28 and later v8 versions
• PostgreSQL: 13.10 and later v13 versions, 14.7 and later v14 versions, and 15.2 and later v15 versions

Cost of enabling Dedicated Log Volumes (DLV) in RDS

The documentation doesn’t say much about additional charges for the Dedicated Log Volumes, but I reached out to AWS support, who responded exactly as follows: 

Please note that there are no additional costs for enabling a dedicated log volume (DLV) on Amazon RDS. By default, to enable DLV, you must be using PIOPS storage, sized at 1,000 GiB with 3,000 IOPS, and you will be priced according to the storage type. 

Are DLVs effective for your RDS instance?

Implementing dedicated mounts for components such as binlogs and datadir is a recommended standard practice. It becomes more manageable and efficient by isolating logs and data to a dedicated mount. This segregation facilitates optimized I/O operations, preventing potential bottlenecks and enhancing overall system performance. Overall, adopting this practice promotes a structured and efficient storage strategy, fostering better performance, manageability, and, ultimately, a more robust database environment.

Thus, using Dedicated Log Volumes (DLVs), though new in AWS RDS, has been one of the recommended best practices and is a welcome setup improvement for your RDS instance.

We performed a standard benchmarking test using the sysbench tool to compare the performance of a DLV instance vs a standard RDS MySQL instance, as shared in the following section.

Benchmarking AWS RDS DLV setup

Setup

2 RDS Single DB instances	1 EC2 Instance
Regular	DLV Enabled	Sysbench
db.m6i.2xlarge	c5.2xlarge
MySQL 8.0.31	CentOS 7
8 Core / 32G	8 Core / 16G
Data Size: 32G

– Default RDS configuration was used with binlogs enabled having full ACID compliance configurations.

Benchmark results for DLV-enabled instance vs. standard instance

Write-only traffic

Read-write traffic

Read-only traffic

Benchmarking analysis

• For both read-only and read-write traffic, there is a constant improvement in the QPS counters as the number of threads increases.
• For write-only traffic, the QPS counters match the performance of standard RDS instances for lower thread counts, though, for higher counters, there is a drastic improvement.
• The DLV, of course, affects the WRITE operations the most, and hence, the write-only test should be given the most consideration for the comparison of the DLV configuration vs. standard RDS.

Benchmarking outcome

Based on the sysbench benchmark results in the specified environment, it is strongly advised to employ DLV for a standard RDS instance. DLV demonstrates superior performance across most sysbench workloads, particularly showcasing notable enhancements in write-intensive scenarios.

Implementation considerations

When opting for DLVs, it’s crucial to be aware of the following considerations:

1. DLV activation requires a reboot: After modifying the DLV setting for a DB instance, a reboot is mandatory for the changes to take effect.
2. Recommended for larger configurations: While DLVs offer advantages across various scenarios, they are particularly recommended for database configurations of five TiB or greater. This recommendation underscores DLV’s effectiveness in handling substantial storage volumes.
3. Benchmark and test: It is always recommended to test and review the performance of your application traffic rather than solely depending on standard benchmarking dependent on synthetic load.

DLV in Multi-AZ deployments

Amazon RDS seamlessly integrates DLVs with Multi-AZ deployments. Whether you’re modifying an existing Multi-AZ instance or creating a new one, DLVs are automatically created for both the primary and secondary instances. This ensures that the advantages of DLV extend to enhanced availability and reliability in Multi-AZ configurations.

DLV with read replicas

DLV support extends to read replicas. If the primary DB instance has DLV enabled, all read replicas created after DLV activation inherit this feature. However, it’s important to note that read replicas created before DLV activation will not have it enabled by default. Explicit modification is required for pre-existing read replicas to leverage DLV benefits.

Conclusion

Dedicated Log Volumes have emerged as a strong option for optimizing Amazon RDS performance. By segregating transaction logs and harnessing the power of dedicated storage, DLVs contribute to enhanced efficiency and consistency. Integrating DLVs into your database strategy will help you toward your efforts in achieving peak performance and reliability.

How Percona can help

Percona is a trusted partner for many industry-leading organizations across the globe that rely on us for help in fully utilizing their AWS RDS environment. Here’s how Percona can enhance your AWS RDS experience:

Expert configuration: RDS works well out of the box, but having Percona’s expertise ensures optimal performance. Our consultants will configure your AWS RDS instances for the best possible performance, ensuring minimal TCO.

Decades of experience: Our consultants bring decades of experience in solving complex database performance issues. They understand your goals and objectives, providing unbiased solutions for your database environment.

Blog resources: Percona experts are actively contributing to the community through knowledge sharing via forums and blogs. For example, here are two blogs on this subject:

Discover how our expert support, services, and enterprise-grade open source database software can make your business run better.

Get in touch