知鸦日报2021-11-14

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. Off the shelf, SMR drives have the reputation of being slower to write to than conventional drives. So the challenge has been to benefit from the cost savings of the denser drives without sacrificing performance. After all, our new products support active collaboration between small teams all the way up to the largest enterprise customers. That’s a lot of data to write, and the experience has to be fast.

In HBO’s Silicon Valley, lossless video compression plays a pivotal role for Pied Piper as they struggle to stream HD content at high speed.

Inspired by Pied Piper, we created our own version of their algorithm Pied Piper at Hack Week. In fact, we’ve extended that work and have a bit-exact, lossless media compression algorithm that achieves extremely good results on a wide array of images. (Stay tuned for more on that!)

However, to help our users sync and collaborate faster, we also need to work with a standardized compression format that already ships with most browsers. In that vein, we’ve been working on open source improvements to the Brotli codec, which will make it possible to ship bits to our business customers using 4.4% less of their bandwidth than through gzip.

Over the past four years, we've been working hard on rebuilding our desktop client's sync engine from scratch. The sync engine is the magic behind the Dropbox folder on your desktop computer, and it's one of the oldest and most important pieces of code at Dropbox. We're proud to announce today that we've shipped this new sync engine (codenamed "Nucleus") to all Dropbox users.

Rewriting the sync engine was really hard, and we don’t want to blindly celebrate it, because in many environments it would have been a terrible idea. It turned out that this was an excellent idea for Dropbox but only because we were very thoughtful about how we went about this process. In particular, we’re going to share reflections on how to think about a major software rewrite and highlight the key initiatives that made this project a success, like having a very clean data model.

作为一名软件工程师，我花费了许多时间来阅读和编写设计文档。在看了几百份这样的文档后发现，优秀的设计文档与项目最终的成功有很大的关系。

在这篇文章中，我尝试去阐述是什么让一份设计文档如此重要。

数学规划的五步法。