DriveDx review: Mac utility provides hints and warnings when your drive is about to fail

Your hard disk drives (HDDs) and solid-state drives (SSDs) “know” quite a bit about how well they’re functioning. Nearly all modern drives of both kinds have internal diagnostics and track other information about usage and wear. But it can be hard to surface that without Terminal commands, and tough to interpret the context, especially for SSDs.

DriveDx from Binary Fruit puts a friendly face on complicated data, and can offer critical information about the state of your drives before a failure. With a database of drive information that the company has compiled, it offers insight that would take far longer to assemble for anyone but a technical expert.

The app reads S.M.A.R.T. (Self-Monitoring, Analysis and Reporting Technology) information that a drive’s internal operating system records. This can include read and write errors, reassigned sectors (an automatic process if a spot on a disk can’t be successfully written to), unexpected events, and incremental counters for items like how much data has ever been written to the drive.

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While you can access S.M.A.R.T. data in other ways and with other software, DriveDx provides the details with context that’s useful to a broad swath of users. It typically shows the raw data (such as number of errors or bytes) along with a status bar that provides a graphical visualization and some text, like “OK.”

DriveDx presents other information it gathers or the results of its analysis in a similar fashion. The label or status on nearly every item can be clicked to bring up detailed information about the property. You can also find out some peculiar and interesting data points, like how often a drive has been powered up and down (whether an internal drive that might be powered down to preserve battery life or an external one you switch on or off),

Health status

If there are errors that need to be addressed or the drive is failing, the software summarizes the problems and offers a Diagnosis button that, when clicked, explains each error and how bad it is.

This can be as severe as “there is a high probability that [the] drive will fail soon,” along with advice like “Backup your data immediately!”

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If you’re actively concerned about drive health, the app can be kept running in the background, and a system menu bar item reveals current drive health status. You can also configure email alerts, if it’s running and you’re away from your Mac. It also monitors available free space to alert you before a drive is full.

The software also offer a “self-test” on many drives in both a long and short format. Instead of relying on reported errors, DriveDx can run it briefly or at length through its paces and see if new errors emerge.

For SSDs, DriveDx is particularly useful, as it calculates the remaining lifetime of the drive. The data cells in SSDs can be read an effectively unlimited number of times, but only written a finite number before they wear out. SSD firmware coupled with operating system support (as in macOS) ensure that new data is written evenly across all available storage to prevent early failure of portions of the drive. (This feature has to be manually enabled in macOS for SSDs added internally.)

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Even with this in place, SSDs will ultimately run out of juice, but the time it takes for a drive to no longer be safely writable varies enormously. SSDs with high capacity, like 1TB, have so many potential locations that may be written, that even with heavy continuous writing, it could last centuries.

Small-capacity SSDs are the problem. Drives under 256GB, especially the small 28GB drives found in Fusion Drives (such as the one in my iMac), can wear more readily under routine to heavy use. A Fusion Drive pairs an SSD with a high-capacity HDD, and macOS continuously rotates data that’s most frequently accessed into SSD storage.

In my iMac’s nearly two years of use with a 28GB SSD and a 1TB HDD, DriveDx calculates that it’s already gone through 10 percent of its expected lifetime. If this keeps up, the drive should far outlast my Mac. However, some users find their particular data patterns put more pressure on SSD writing, and may have just a few years left on a relatively new machine. While most modern Macs can’t have their SSDs swapped out, at least you’d be able to be forewarned as the potential end of life approached.

External drive support

To use DriveDx with external drives, you have to install an included driver. A hardware driver is rare for any modern Mac software, but necessary to access the S.M.A.R.T. data as Apple doesn’t provide another path, according to the developer. You have to approve the installation of the driver via macOS’s Security & Privacy preference pane, and typically restart your Mac to have the data become available.

As with any third-party driver, you should be alert to whether you see any odd system behavior after installation that might indicate compatibility problems with other software or macOS. (In my testing, I saw no issues.)

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The proof of diagnostic software is when it tells you something’s wrong before you’re aware of it. That happened in testing DriveDx. One of my external drives, used to store iTunes and Photos libraries, had quietly generated a huge number of write errors, which were automatically corrected, but are an extremely bad indication of the drive’s future reliability. 

DriveDx provided detailed information about what was wrong, and suggested an immediate backup. I was able to transfer 1.5TB of data successfully, averting a potential failure. Yes, I have a backup, but averting failure is better than relying on a backup.

Just days later, my other external drive to which I’d just used to transfer all that data to? It started generated less severe errors, but ones that hinted at an upcoming failure. I began shifting data from it, only to see have malfunctions during copying.

Had I not been running DriveDx, I likely would have lost both drives without advance notice. (Both drives were four years old. They don’t make them like they used to?)

Bottom line

The best thing you can do to preserve data is to have multiple backups in different places. But the best option to prevent data loss before a drive fails is to run DriveDx. It’s affordable for a single copy and in a family license, and can prevent loads of wasted time or erratic performance that far outweighs its cost.