Chapter in this post:
Only recently I came across the small tool "DriveDx" through a report in the English Macworld (here the Download link). This Mac app can be used to monitor internal and external hard drives by checking the SMART status (Wiki) of the drive is queried and evaluated.
SMART stands for Self-Monitoring, Analysis and Reporting Technology - In other words: A system with which the hard drive can monitor itself and output analyzes and status reports. The whole thing is an industry standard and is now available in almost all hard drives, but as a user you usually don't see much of it unless you have just installed software like DriveDx.
The Wikipedia page has an interesting note on this subject. In 2007 there was a study with the title "Failure Trends in a Large Disk Drive Population" (see PDF). Over 100.000 hard drives from different manufacturers were monitored and failures were evaluated - including the messages that the SMART system issued.
The result: in approx. 64% of the cases a failure of the hard disk with the data of the SMART system could be predicted. But that still leaves a third of the failures for which analyzes could not be prepared. Nevertheless, the SMART analysis has a certain informative value and can, under certain circumstances, provide information on when it is better to move your data to another hard drive.
When you load DriveDx onto the Mac, you can only evaluate the Mac's internal hard drives at first. Depending on your Mac, you may run into one or the other problem when viewing the other drives. For example, it happened to me that I could see the external hard drives in the DriveDx list, but they did not transfer any information to DriveDx - even though I installed the USB driver for the software and given the security clearance in Mojave have.
After a short email exchange with DriveDx support, it was also clear why this was the case: On Macs with the T2 security chip (such as the MacBook Pro from 2018 or the iMac Pro), the USB driver from DriveDx is activated by the macOS when booting Driver overwritten. This means that DriveDx cannot access the external hard drives after the system has started.
However, the solution is very simple: pull out the hard drive (after ejecting it in the Finder) briefly unplugged from the Mac and plugged it in again. For me, the external hard drives then appeared with all evaluations in DriveDx. After a restart, however, the problem occurs again and you have to disconnect the hard disks again briefly if you want to run evaluations with DriveDx.
There are numerous instructions in the FAQ or the knowledge base.
In the last few years I have managed to paralyze my Mac exactly once by completely filling the startup disk with data. The whole thing happened when cutting videos with Adobe Premiere, but a few gigabytes of new data quickly develop that want to be written somewhere. When the hard drive space on my "Macintosh HD" was at some point only a few hundred megabytes, the finder hoisted the white flag and hung himself up.
As a rule, you will notice that the hard drive is getting full long in advance because the finder is getting tougher and has small dropouts every now and then. These arise because he is desperately trying to shovel data back and forth in order to be able to continue somehow. For me, however, there was an abrupt transition from normal operation to "inoperable", as Adobe Premiere filled all available hard disk space on the system disk within a few minutes.
In order to avoid such problems in the future, you can use a helpful feature of DriveDx, which sends out warnings in the form of notifications if you fall below freely definable limits (in percentages). These limits can be set separately for each hard drive, but here, too, I had the problem with the T2 chip: After every restart, DriveDx has no access to the corresponding data on the external hard drives if I don't unplug them for a short time.
In addition to checking via the DriveDx interface, there is also the option of having automated reports emailed by the software. These can either be created time-controlled at certain intervals or triggered by warnings from the hard disks.
This is helpful, for example, if you want to keep an eye on the hard drive health of servers or the Macs of friends who live remotely. Of course, you can also have a report of your own drives emailed to you.
To show how the DriveDx evaluation works, I checked all of my external hard drives. Most of them showed no particular problems, but DriveDx found some of the items.
The nice thing is that at DriveDx, the things that have been criticized are clearly and comprehensibly presented, even for laypeople, with green, orange or red bars and terms such as "ok" and information in percent. So you can find out about the health of your hard drives without having completed a degree in computer science.
Many of the values in the detailed evaluation may at first glance be a bit cryptic in terms of the names, but the hints that you get by moving the mouse over the corresponding values give a good insight into what the data say and which values are normal would be.
Here I have a few screenshots for you that show some "abnormal" points on my drives:
I haven't missed DriveDx and I will probably not open it every day in the future either. The peculiarity of the software to stay in the background and only give me a hint when there is a warning is very nice for me. I have a lot of family photos, several hard drives with film material and backup copies of customer websites slumbering on various drives. Some of it will be fine backed by Backblaze, but some things are only available once. So it is a blessing to be informed before an imminent failure that the hard drive may soon be running out of time.
Especially for people who do not work a lot with backups, you should perhaps use DriveDx in order to be able to pull a copy of the data in an emergency before the failure. But don't forget: According to the study, 36% of failures could not be predicted!
What is impractical in my special case, however: I cannot have any reports sent to me by e-mail or receive automatic warnings when my hard drives are full. This is because my external hard drives are unreadable for DriveDx if I haven't even unplugged and reconnected them from the Mac after every restart (the explanation for this is above).
In everyday life, however, I start my MacBook Pro with all the drives plugged in and I am not willing to repeatedly unplug and plug in the hard drives when I restart. For this reason I will probably put a reminder in my calendar and simply check the drives manually every three to four weeks with DriveDx.
In any case, I don't want to do without the functionality of DriveDx. And I'm almost looking forward to the first hard drive that gives me a warning to see when it actually gives up the spoon. ;-)
Interested in the software? Here is the bottom of the developer:
If you install DriveDx, a so-called daemon is of course also installed. A process that runs constantly in the background and - even if it does not require a lot of resources - can still be a potential pre-cause of problems. I haven't noticed any problems directly with DriveDx, but after my MacBook Pro kept crashing at the end of last year, I eventually threw everything out of the system that wasn't really necessary. I also installed the system several times over it to iron out small errors.
Ultimately, DriveDx got hold of me at some point and was banned from the record. The features are nice, but I didn't reinstall DriveDx. I think with the new version of macOS (Big Sur), the third-party kernel extensions are no longer wanted by macOS. It is therefore questionable whether DriveDx would have made it into my current system anyway.
At first I thought DriveDx would no longer be feasible with macOS Big Sur. In fact, there is a comment from the developers Binary Fruit about how DriveDx also works with external hard drives under macOS Big Sur. I once translated the post for you - with the help of DeepL:
macOS 11 Big Sur does not load non-Apple drivers during startup. So if the external drive was connected before or during system startup, macOS will not load a third-party driver for it. So far, this behavior (the so-called "Secure Boot") only applied to Macs with a T2 chip, since Big Sur it has now been applied to all Macs (even without a T2 chip).
After the system has finished booting, physically disconnect and reconnect the external USB drive (s). This will force macOS to load the driver for the newly connected drive (s). Then restart DriveDx.
Note: for Macs with a T2 chip there is an option to disable "Secure Boot" via recovery mode, but it is currently not clear how to do this for Macs without a T2 chip. And it's not currently clear whether this is a new feature in Big Sur or a bug in Big Sur that could be fixed in future versions of macOS.
So you have to forego a bit of comfort and safety in order to be able to use the DriveDx functions. From my point of view, it is questionable whether this exchange should be made. I am a little cautious in this regard and would rather do without DriveDx.
Jens has been running the blog since 2012. He appears as Sir Apfelot for his readers and helps them with problems of a technical nature. In his free time he drives electric unicycles, takes photos (preferably with his iPhone, of course), climbs around in the Hessian mountains or hikes with the family. His articles deal with Apple products, news from the world of drones or solutions for current bugs.