2022 APFS Advent Challenge Day 22 - Retrospective

Friday, December 30, 2022

As 2022 ends, so does my APFS Advent Challenge. Deciding at the last minute to write this series of blogs turned out to be even more challenging than expected. Life tends to find a way to complicate things, and December was no exception for me this year. I am glad I stuck with the challenge and hope that the information provided in the series was of some value to you.

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2022 APFS Advent Challenge Day 21 - Fusion Containers

Thursday, December 29, 2022

As we discussed in an earlier post, Apple’s Fusion Drives combine the storage capacity of a hard disk drive (HDD) with the faster access speed of a solid state drive (SSD). The HDD is the primary storage device, and the SSD acts as a cache for recently accessed data. However, the Fusion Drive does not have built-in caching logic, and the operating system treats the two drives as separate storage devices. Apple created Core Storage to support the desired caching capabilities and the ability to pool the storage of each device into a single logical volume. APFS removes the need for Core Storage by having first-class support for this tiered storage model. This post will go into more detail about APFS Fusion Containers.

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2022 APFS Advent Challenge Day 20 - Snapshot Metadata

Wednesday, December 28, 2022

Our previous discussion discussed how Object Maps facilitate the implementation of point-in-time Snapshots of APFS file systems by preserving File System Tree Nodes from earlier transactions. In that discussion, I outlined the on-disk structure of the Object Map Snapshot Tree and how it can be used to enumerate the transaction identifiers of each Volume Snapshot. Today, we will briefly discuss two other sources of information that store additional metadata about each Snapshot.

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