Storage (Disk Drive) Decision-Making

Dr. Mac’s Rants & Raves
Episode #409

People ask me many questions about their Macs, and many (if not the majority) of those questions have to do with disks and storage. Their issues fall into three main categories:

    • My startup disk is dead or dying.
    • My startup disk is nearly full.
    • I need a backup disk (or an additional backup disk).

Solid-State Disks vs. Hard Disks

If your dead or dying startup disk is a hard drive, replacing it with a solid-state drive (SSD) will significantly improve your Mac’s performance. It will also cost significantly more per gigabyte than a slower mechanical hard drive. Still, in my humble opinion, an SSD will make your Mac feel so much faster and more responsive it’s worth every penny.

Desktop Mac users can save a bit of cash by not replacing the dead internal drive at all. Instead, purchase an external drive—preferably a solid-state USB 3 drive—and use that as your boot disk.

Fullness = Slowness

To see if your startup disk is nearly full, select its icon in the Finder and choose File–>Get Info. When there is 10% or less space available, you’re likely to start experiencing slowdowns or worse. And, the closer it gets to 100%, the more likely you’ll soon encounter big trouble.

So, the first thing to do is determine which files or folders in your Home directory are using the most disk space. The easiest (and least expensive) way is to choose About This Mac from the Apple menu, click the Storage tab, and then click the Manage button.

On the Manage screen, choose Recommendations in the sidebar to see a quartet of options for managing your files.

The Manage screen offers myriad free options for managing large files.
The Manage screen offers myriad options for managing (and eliminating) large files.

Or, click one of the file types below Recommendations in the sidebar (namely Applications, Messages, Music, Photos, and such) to see your files of that type sorted by size. Then, click an item (or Command+click to select multiple items), and click Delete to remove them permanently.

Relocate Media to an External Drive

Don’t forget that if your Music, Movies, or Pictures folders are part of the problem, it’s easy to move their contents to an external drive via the Preferences windows of the Music, iTunes, Movies, or Photos apps. Once again, an external SSD will be faster and more responsive than a hard disk at a higher cost per gigabyte.

How I Shop for Storage

Finally, look for a backup disk at least 2X the size of your startup disk (and preferably larger). Some people (not me) agonize over MTBF (mean time between failure) statistics before buying. I believe all drives will fail eventually and plan for that with a redundant backup system. So, I shop for the least expensive drive that serves my needs. Then, I duplicate (or triplicate) its contents to another disk or cloud storage.

One more thing: I’ve relied upon Backblaze for my cloud-based backups for nearly a decade. At $6 a month for unlimited backups, it’s cheap insurance against disaster.

5 thoughts on “Storage (Disk Drive) Decision-Making

  • Thanks for the review. In my experience, not all disks were created equal. Some work great, but others generate all sorts of problems, including not mounting themselves (or preventing other external disks to mount) when cold booting the Mac, unexpected ejects, freezing Mac, crashes, kernel panics, etc.

    Another aspect to take into account is the thermal characteristics. For instance, some SSD like the Samsung Portable SSD T5 (even the 2 TB model) remains cold when booting the Mac and working all day from it. Others get very hot, even when idle and even when unmounted. That talks about the technology inside. Some experience thermal throttling. Finally, others reach even 72 degrees C that can burn your hand (!!!) and even destroy themselves. For insance, check out the Sabrent Rocket XTRM-Q SSD (500 GB to 8 TB). Really amazing!

    1. I hear you, but in my experience, such problems quickly become apparent. As long as you buy disks from trusted sources, you should be able to return any disk that has issues for refund or replacement. I hope that helps.

  • OK I’ve got a 2016 iMac and I think I’ll be looking at this next year some time. The internal Fusion drive is getting long in the tooth. So as far as an SSD, replacing the internal drive would be the cleanest, but most expensive because these things are terrible to get into. I’ve been looking at an external but which would you recommend USB3 or Thunderbolt 2? Now TB2 drives are scarce as hen’s teeth, but as I understand they are faster. I don’t believe I can plug a TB3 into a 2 port.

      1. Indeed, that is also my experience. And even more surprising: most users do not know that, but you cannot tell the difference when booting Mac and working all day long from a fast internal SSD (3,000 MB/s read & 2,000 MB/s write) or an external one like the Samsung Portable SSD T5 (500 Mb/s read-write) using USB 3.2 Generation 2 at 10 Gbps; you notice difference when using the slower USB 3.2 Generation 1 at 5 Gbps port on Mac), except if you work with huge monolithic files like movies. The reason is that once a threshold is reached, the key factor is the random IOPS read-write benchmarks. For instance, a Mac with a high IOPS could boot in 5 seconds instead of 20 seconds, for instance.

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