A Feat of Engineering

🌈 Abstract

The article discusses Apple's engineering feat in silently migrating hundreds of millions of iOS devices to a new file system (APFS) with the release of iOS 10.3, without users noticing any difference.

🙋 Q&A

[01] A Feat of Engineering

1. What was the key engineering feat that Apple accomplished with the iOS 10.3 update?

• Apple silently migrated hundreds of millions of iOS devices to the new Apple File System (APFS) with the iOS 10.3 update, and users did not notice any difference.
• This was a massive undertaking, as migrating the file system of such a large number of devices carries a high risk of issues, but Apple was able to execute this seamlessly.

2. How did Apple approach testing and rolling out this file system migration?

• Apple had a process for testing the file system migration in previous iOS 10.1/10.2 updates, where they would trial the migration, run consistency checks, and then roll it back to gather data on how it worked in the field.
• For the iOS 10.3 update, they likely had extensive testing on hundreds or thousands of devices to ensure the migration would work smoothly across a wide range of configurations.

3. What factors contributed to Apple's ability to execute this file system migration successfully?

• Apple wrote the new APFS file system, so they had deep understanding and experience with it.
• They had the engineering expertise and tools to properly migrate from the old file system to the new one.
• As a company, Apple has extensive experience with automatically updating iOS devices, which helped them roll out this migration at scale.

[02] Comparison to Personal File System Migrations

1. How does the author's personal experience with file system changes compare to Apple's execution of the APFS migration?

• The author notes that they have personally struggled with accidentally destroying Linux and Windows installations when making file system changes, as it is a very risky and load-bearing operation.
• In contrast, Apple's team had the expertise, testing, and tooling to execute the APFS migration with near-zero risk of bricking devices, despite the massive scale.

2. What factors made Apple's file system migration more successful than the author's personal experiences?

• Apple wrote the new APFS file system, so they had deep understanding of it.
• They likely tested the migration extensively on hundreds or thousands of devices to ensure it would work across a wide range of configurations.
• As a large company, Apple has significant experience with automatically updating iOS devices, which helped them roll out the migration smoothly.