AWS Nitro SSD – High Performance Storage for your I/O-Intensive Applications

We love to solve difficult problems for our customers! As you have seen through the years, innovation at AWS takes many forms, and encompasses both hardware and software.

One of my favorite examples of customer-driven innovation is AWS Nitro System, which I first wrote about back in mid-2018. In that post I told you how Nitro System would allow us to innovate more quickly than ever, with the goal of creating instances that would run even more types of workloads. I also shared the basic building blocks, as they existed at that time, including Nitro Cards to accelerate and offload network and storage I/O, the Nitro Security Chip to monitor and protect hardware resources, and the Nitro Hypervisor to manage memory and CPU allocation with very low overhead.

Today I would like to tell you about one more building block!

AWS Nitro SSD
For decades, traditional hard drives (sometimes jokingly referred to as spinning rust) were the primary block storage devices. Today, while spinning rust still has its place, most high-performance storage is based on more modern Solid State Drives (SSD). Open up an SSD and you will find lots of flash memory and a firmware-driven processor that manages access to the memory and supports higher-level functions such as block mapping, encryption, caching, wear leveling, and so forth.

The scale of the AWS Cloud and the range of customer use cases that it supports gives us some valuable insights into the ways that today’s applications, database engines, and operating systems make use of block storage. As a result, after delivering several generations of EC2 instances we saw an opportunity to do better. Our goal was to allow I/O-intensive workloads (relational databases, NoSQL databases, data warehouses, search engines, and analytics engines to name a few) to run faster and with more predictable performance.

Today I would like to tell you about the AWS Nitro SSD. The first generation of these devices were used to power io2 Block Express EBS volumes, and allow us to give you EBS volumes with lots of IOPS, plenty of throughput, and a maximum volume size of 64 TiB. The Im4gn and Is4gen instances that I wrote about earlier today make use of the second generation of AWS Nitro SSDs, as will many future EC2 instances, including the I4i instances that we preannounced today.

The AWS Nitro SSDs are designed to be installed and to operate at cloud scale. While this sounds like a simple exercise in manufacturing and installing more devices, the reality is a lot more complex and a lot more interesting. As I noted earlier, the firmware inside of each device is responsible for implementing many lower-level functions. As our customers push the devices to their limits, they expect us to be able to diagnose and resolve any performance inconsistencies they observe. Building our own devices allows us to design in operational telemetry and diagnostics, along with mechanisms that enable us to install firmware updates at cloud scale & at cloud speed. Taking this even further, we developed our own code to manage the instance-level storage in order to further improve the reliability and debug-ability, and to deliver consistent performance.

On the performance side, our deep understanding of cloud workloads led us to engineer the devices so that they can deliver maximum performance under a sustained, continuous load. SSDs are built from fast, dense flash memory. Due to the characteristics of this semiconductor memory, each cell can only be written, erased, and then rewritten a limited number of times. In order to make the devices last as long as possible, the firmware is responsible for a process known as wear leveling. I don’t understand the details, but I assume that this includes some sort of mapping from logical block numbers to physical cells in a way that evens out the number of cycles over time. There’s some housekeeping (a form of garbage collection) involved in this process, and garden-variety SSDs can slow down (creating latency spikes) at unpredictable times when dealing with a barrage of writes. We also took advantage of our database expertise and built a very sophisticated, power-fail-safe journal-based database into the SSD firmware.

The second generation of AWS Nitro SSDs were designed to avoid latency spikes and deliver great I/O performance on real-world workloads. Our benchmarks show instances that use the AWS Nitro SSDs, such as the new Im4gn and Is4gen, deliver 75% lower latency variability than I3 instances, giving you more consistent performance.

Putting all of this together, there’s a very tight, rapidly rotating flywheel in action here because the team that builds the Nitro SSDs is part of the AWS storage team, and also has operational responsibilities. Like all teams at AWS, they watch the metrics day-in and day-out, and can efficiently deploy new firmware using a CI/CD model.

Join the Team
As is always the case, there’s always more innovation ahead, and we have some awesome positions on the teams that design the AWS Nitro SSDs. For example:

• Software Development Manager – Storage Infrastructure Team
• Senior Technical Program Manager – Storage
• Senior Firmware Development Engineer – Solid State Devices
• Senior Systems Development Engineer – Storage
• Senior Hardware Development Engineer – Storage

— Jeff;