Ever since we launched Magic Pocket, our in-house multi-exabyte storage system, we’ve been continuously looking for opportunities to improve efficiency, while maintaining our high standards for reliability. Last year, we pushed the limits of storage density by being the first major tech company to adopt SMR storage. In this post, we’ll discuss another advance in storage technology at Dropbox: a new cold storage tier that’s optimized for less frequently accessed data. This storage runs on the same SMR disks as our more active data, and through the same internal network.
The Lifetime of a file
The access characteristics of a file at Dropbox varies heavily over time.
Magic Pocket, the exabyte scale custom infrastructure we built to drive efficiency and performance for all Dropbox products, is an ongoing platform for innovation. We continually look for opportunities to increase storage density, reduce latency, improve reliability, and lower costs. The next step in this evolution is our new deployment of specially configured servers filled to capacity with high-density SMR (Shingled Magnetic Recording) drives.
Dropbox is the first major tech company to adopt SMR technology, and we’re currently adding hundreds of petabytes of new capacity with these high-density servers at a significant cost savings over conventional PMR (Perpendicular Magnetic Recording) drives.
We’ve received a lot of positive feedback since announcing Magic Pocket, our in-house multi-exabyte storage system. We’re going to follow that announcement with a series of technical blog posts that offer a look behind the scenes at interesting aspects of the system, including our protection mechanisms, operational tooling, and innovations on the boundary between hardware and software. But first, we’ll need some context: in this post, we’ll give a high level architectural overview of Magic Pocket and the criteria it was designed to meet.
There is nothing more important to Dropbox than the safety of our user data. When we set out to build Magic Pocket, our in-house multi-exabyte storage system, durability was the requirement that underscored all aspects of the design and implementation. In this post we’ll discuss the mechanisms we use to ensure that Magic Pocket constantly maintains its extremely high level of durability.
This post is the second in a multi-part series on the design and implementation of Magic Pocket. If you haven’t already read the Magic Pocket design overview go do so now;
Years ago, we called Dropbox a “Magic Pocket” because it was designed to keep all your files in one convenient place. Dropbox has evolved from that simple beginning to become one of the most powerful and ubiquitous collaboration platforms in the world. And when our scale required building our own dedicated storage infrastructure, we named the project “Magic Pocket.” Two and a half years later, we’re excited to announce that we’re now storing and serving over 90% of our users’ data on our custom-built infrastructure.
A year ago, we became the first major tech company to adopt high-density SMR (Shingled Magnetic Recording) technology for our storage drives. At the time, we faced a challenge: while SMR offers major cost savings over conventional PMR (Perpendicular Magnetic Recording) drives, the technology is slower to write than conventional drives. We set out on a journey to reap the cost-saving benefit of SMR without giving up on performance. One year later, here’s the story of how we achieved just that.
The Best Surprise Is No Surprise
When the first production machines started arriving in September,