Upgrade to High Sierra: Understanding the Conversion Process

When upgrading to macOS High Sierra (10.13), one of the most significant changes you'll encounter is the conversion of your startup volume from HFS+ to APFS, Apple's new file system technology. While this process is designed to improve the overall performance and stability of your Mac, it's essential to understand what's involved and how to prepare for the upgrade.

Firstly, it's crucial to ensure you have sufficient free disk space on your startup volume to contain both its current HFS+ metadata and the replacement APFS metadata. Trying to convert a volume with insufficient free space is likely to throw an error, increasing the risk of disaster.

Fortunately, Apple's High Sierra installer automatically converts startup volumes on SSDs to APFS during the upgrade process. However, startup volumes on Fusion Drives and hard drives will not be converted at this time. The good news is that if you have a Time Machine backup set up, you can rely on it in case something goes wrong during the upgrade.

The conversion tool used by High Sierra does several important tasks:

* It finally deletes the old HFS+ volume metadata, leaving the volume in APFS format.

* If no errors occurred, it then writes the volume superblock in APFS format, replacing the HFS+ data.

* It checks that the APFS metadata appear correct.

* It converts existing HFS+ volume metadata (directories, etc.) to APFS format and writes those metadata to free space on the disk.

While Apple has been testing this tool for almost a year, it's essential to be prepared for potential issues during the upgrade process. There are two major risks: first, that the conversion of your startup volume from HFS+ to APFS fails, and second, that key software proves incompatible with APFS (or another part of the upgrade).

To mitigate these risks, make sure you have a backup of your Mac before starting the upgrade process. Additionally, be aware that High Sierra provides an optional let-out that doesn't convert your startup volume to APFS.

When deciding to upgrade to High Sierra, it's crucial to prepare for the upgrade by ensuring you have sufficient free disk space and having a backup ready. By understanding what's involved in the conversion process, you can avoid potential issues and ensure a smooth transition to Apple's latest file system technology.

Upgrade to high sierra