As the amount of data we store continues to grow, figuring out where to put it and how to access it becomes more complicated. It’s not just that we need to find space for our increasingly large collections of photos, videos, music, and apps—we want it to be available whenever we need it, and be sure that it’s safe from hackers and thieves.
Every Mac includes internal storage in the form of a hard drive, SSD, or Fusion drive. But you may also have one or more external devices (such as hard drives, flash drives, SD cards, or RAID devices), not to mention network-attached storage (NAS) devices or cloud storage (like Dropbox or iCloud Drive). Making sense of all your options, managing your stored data, choosing new devices or services when you’re running out of space, or even just figuring out what’s where can drive anyone to distraction.
“Highly recommend Take Control of Your Digital Storage from @TakeControl books! Like all their titles, well-written, super easy to understand, with vital, vital information! I learned a ton and I’m only up to page 30! A must read…I used to teach this subject in workshops at Apple and thought I knew it all! But I still learned so much valuable information.” —Lars Hoel
Fortunately, Jeff Carlson has a book with all the answers! After decades of working with Macs and accumulating massive collections of photos and videos, Jeff has pulled together a wide-ranging book about Mac storage that contains just the help you’re looking for. Among many other topics, this book covers:
- How to choose a new hard drive, SSD, or hybrid drive
- Determining how much storage space you need
- What you need to know about APFS, Apple’s new filesystem
- How to use APFS snapshots (a.k.a. Time Machine local snapshots)
- Formatting and partitioning disks using Disk Utility
- How to repair a misbehaving disk
- RAIDs: what they are and how different types compare
- How to tell when a hard drive is about to fail, and what to do about it
- What to do with a hard drive when it has outlived its usefulness
- When to use a flash drive or SD card
- How to create and use disk images
- Deciding among local, network, and cloud storage for various types of files
- What a personal cloud is and why you might consider using one
- Strategies for freeing up extra disk space
The expanded third edition brings the book up to date with macOS 15 Sequoia. It also now covers:
- Using external storage with an iPhone or iPad, including how to format external disks
- Thunderbolt 5
- More ways to free up disk space
NAS devices get special coverage, including:
- Why you might want a NAS
- How to choose a NAS—and when it’s a better idea than an external hard drive
- Using a NAS with your Mac for a wide variety of purposes
- Special considerations when using a NAS for digital photos
Jeff also digs into details about numerous storage-related technologies:
- How to tell whether your third-party SSD needs to have TRIM enabled (and what to do if the answer is yes)
- How to create a software RAID using Disk Utility or SoftRAID
- What you need to know about filesystems—and how to choose among APFS, Mac OS Extended, FAT, and ExFAT
- Why and how to encrypt a disk using FileVault or the Finder
- Using iCloud Drive’s Optimized Mac Storage feature
If you’ve ever been stumped at the difference between a volume and a partition, need help figuring out whether to buy a big external hard drive or a NAS for extra storage, or want to make sense of Apple’s APFS filesystem, this book will tell you what you need to know.
What’s New in the Third Edition
The digital storage world has been relatively stable for the last couple of years, especially compared to the time before that when Apple was making big changes under the surface with APFS (Apple File System) over several system releases. But that doesn’t mean everything is static. Here are the main changes in this edition of “Take Control of Your Digital Storage”:
- The book has been updated to reflect changes in macOS 15 Sequoia, including updated screenshots.
- I’ve deleted mentions of system versions prior to macOS 13 Ventura to keep things current.
- Added more detail about the TRIM feature of SSDs in “Get an Old SSD into Fighting TRIM.”
- Thunderbolt 5 is a new connection protocol that promises even faster speeds. I’ve added a new section on it in the discussion of “External Drives.”
- Macs are no longer the only Apple devices that can erase external disks. See “Format a Disk Connected to an iPhone or iPad.”
- Hyperspace is a novel new utility for freeing up disk space using a core feature of APFS. See “Free Up Disk Space.”
- Your Mac isn’t the only place you need to access files. On your iPhone and iPad, the Files app is the window to file management, particularly on devices with USB-C ports that can connect to external drives. See “Use External Storage on iPad and iPhone.”
- Added a tip about a bug in macOS 15.2 Sequoia and earlier where iCloud Photos could be storing too much cached data on your disk. See “Free Up Disk Space.”
- Another suggestion added to “Free Up Disk Space” is to store large music and video files on external drives and stream the media instead.
Posted by Joe Kissell on September 18, 2025
Jeff Carlson joined host Chuck Joiner on MacVoices to talk about Take Control of Your Digital Storage.
In part one, Jeff discusses a wide range of topics, including SSDs versus hard drives, the APFS file system, and connecting external storage to iPhones and iPacs.
In part two, Jeff goes into more detail about NAS devices and other storage media.
Posted by Joe Kissell on June 13, 2022
Jeff Carlson joined host Chuck Joiner on MacVoices to talk about Take Control of Your Digital Storage, including USB4, Thunderbolt 4, and APFS volumes.
Posted by Joe Kissell on August 7, 2020
Jeff Carlson joined Chuck Joiner on MacVoices in a two-part interview to discuss the second edition of his book Take Control of Your Digital Storage.
In Part 1, Jeff discusses APFS snapshots, mechanical drives vs. SSDs, and making storage purchase decisions.
In Part 2, Jeff talks about Fusion drives, the pros and cons of large external hard drives, and multicolored USB connectors.
Posted by Joe Kissell on June 12, 2020
Jeff Carlson joined Chuck Joiner on MacVoices in a two-part interview to discuss the APFS snapshot capability in macOS.
In Part 1, Jeff explains what snapshots are, how they relate to Time Machine, and where to find them.
In Part 2, Jeff discusses managing and deleting snapshots, and how they affect Disk Utility.
Posted by Jeff Carlson on April 22, 2019
Just as the file system under macOS works quietly, without fanfare, so do the preparations for the next update to Take Control of Your Digital Storage. We’re working on fleshing out the book for an update later this year, but in the meantime, I want to note a few areas where the march of technology has surpassed what’s in the current edition.
AFPS Everywhere
With the release of macOS Mojave in late 2018, APFS (Apple File System) is now the default file system for all Macs running the latest system, regardless of what type of storage the computer runs. Previously, APFS kicked in only for Macs running solid-state memory, like current laptop models. The exception was Fusion drives, which combine a traditional mechanical (spinning magnetic platters) drive for mass storage and SSD memory for caching frequently used files and the system itself to improve performance. (See the sidebar on page 57, “Which Filesystem for Which Drive?”)
This change has resulted in mixed performance—many people with iMacs and other computers with mechanical drives are seeing worse performance following the update. I’m hoping Apple is working through these issues, and we’ll see performance parity with whichever macOS update is announced at WWDC in June.
I still recommend formatting external mechanical drives as Mac OS Extended instead of APFS. Time Machine drives must still be Mac OS Extended, too.
APFS is a fascinating, deep change to macOS that should be invisible for most people, and I think it mostly succeeds at that. But when things go sideways, that can do so in weird ways. For example, the way it treats free space differently than before, leading to situations where your Mac reports a lot of available storage but an application sees far less. I wrote about this in a recent Seattle Times column, where the culprit was several invisible snapshots: Try these strategies to free storage on your Mac.
If you don’t yet own the book and are curious about just what I’m talking about, I recommend (a) buying the book!, or (b) read this TidBITS article: What APFS Does for You, and What You Can Do with APFS (and then buy the book!).
As I get further along with the book update, we’ll post more information here.
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