Knowledge base & Troubleshooting (FAQ)
External drives support on the latest Macs – How-To
General
DriveDx = Drive Diagnostics. Dx is medical shorthand for Diagnostics/Diagnosis in USA and some other countries.
We are not providing official support for Beta-versions of macOS.
Software issues
Check drive “S.M.A.R.T. status” in the Apple Disk Utility. If “S.M.A.R.T. status” is “Not supported” – this means that something broke S.M.A.R.T. subsystem in macOS on your Mac. If you have “iStat Menus” app installed – it could be the root cause of the problem. Recent versions of “iStat Menus” app could break S.M.A.R.T. support in macOS.
To restore S.M.A.R.T. support on your Mac, follow next instructions:
- In the “iStat Menus” app – menu item “Menubar > Monitor S.M.A.R.T. Disks” must be unchecked
- Select menu “iStat Menus > Reinstall…”
- Check drive “S.M.A.R.T. status” in the Apple Disk Utility. If “S.M.A.R.T. status” is “Verified” – S.M.A.R.T. support is successfully restored.
Learn more in our blog post.
If you are getting update error “the app is running from read-only volume” but the app is in the “/Applications” folder. This is macOS security feature named “Path Randomization” introduced in macOS Sierra. macOS launches all recently downloaded (“quarantined”) apps from a special read-only volume with a random path.
How to fix:- delete app bundle
- re-download app
- move app to the “/Applications” folder using (!) Finder.
IMPORTANT: only Finder removes special “quarantine flag”, but third-party file managers are not!
Most probably you are trying to launch DriveDx from the “Downloads” folder or you moved it from the Downloads folder using 3rd party file manager instead of Finder. Recent versions of macOS prohibit auto-launch of applications recently downloaded from the internet. This is macOS security feature named “Path Randomization” introduced in macOS Sierra.
How to fix:IMPORTANT: only Finder removes special “quarantine flag”, but third-party file managers are not!
S.M.A.R.T. data and Health indicators
Cyclic redundancy check (CRC) is a method of verifying and correcting data after it is sent. What this warning is telling you is that at one point, data being sent/received by the drive failed this check. The most common cause for this is a faulty cable. It already occurred so switch cables won’t reset the SMART log. You just need to watch for additional errors.
Drive’s firmware holds and reports overall error count during drive lifetime. The firmware does not reset this value because it has no idea (not aware) that you replaced cables. DriveDx shows data that reported by drive firmware and not aware that cables changed too.
On modern SSDs (especially PCIe/NVMe-based) “Power On Hours” value may not include a time that SSD controller was powered and in a Non-Operational Power State (NOPS). This feature has a good influence on power consumption and drive’s temperature. In such case, the “Power On Hours” (raw) value could be relatively small as modern SSDs are very energy effective and extremely fast.
On modern SSDs (especially PCIe/NVMe-based) power cycle may not include a time that SSD controller was powered and in a Non-Operational Power State (NOPS). This feature has a good influence on power consumption and drive’s temperature. In such case, the “Power Cycle Count” (raw) value could be relatively big as the number of power cycles is increased by 1 every time the SSD wakes up from Non-Operational Power State. See also question “SSD Power On Hours value is ‘small’”.
Q: I’ve installed new SSD to my Macbook Pro for 2 days and is still showing “0” hours on the Power on time indicator in DriveDx report. Can you tell me why this indicator shows “0” although it has 7 power cycles count?
A: If drive real working time is less than 1 hour – drive’s firmware will report power on time = 0. Modern SSDs are very energy effective, so there is an even inverse relationship between power cycle count and power on time values. The more energy efficient drive – the more “power cycles” and the less “power on time”. See question “SSD Power On Hours value is ‘small’”
“Battery Cycle Count” and drive’s “Power Cycle Count” have no relation:
- Battery Cycle Count – shows the number of battery charging cycles. It refers to how much the battery is used. A single load cycle is the cumulative usage of 100% of the battery’s capacity.
- Power Cycle Count – shows the number of drive complete power on/off cycles. macOS Power Management (Energy Saver) could power on/off drive many times in a hour. On modern SSDs the number of power cycles could be increased by 1 every time the SSD wakes up from Non-Operational Power State (NOPS). See also question “SSD Power Cycle Count value is ‘big’”
Temperature indicator raw value usually reports current temperature in
Celsius.
Current (normalized) value = 100 – raw value.
Rating value in percent (and “progress bar”) shows the proximity of drive current temperature to temperature threshold (maximum allowed temperature limit) – how the drive is close to overheating. The smaller the rating the closer the drive to overheating.
- Possible statuses are:
- ok
- close to overheating
- very close to overheating
- overheating
Given: “Drive maximum operating temperature is 65 Celsius (by vendor spec). Drive current temperature is 55 Celsius.”
———
Raw value will be 55.
(Normalized) value = 100 – raw value = 100 – 55 = 45
Threshold = 100 – max operating temperature = 100 – 65 = 35
Rating = (value – threshold) / (100 – threshold) = (45 – 35) / (100 – 35) = 10 / 65 = 0.15 = 15 %
DriveDx will auto start to warn you when the drive is close to overheating. If you want to disable temperature-related warnings – click on progress bar or rating value and choose “Ignore All Rating Changes”.
Results may fluctuate in time due to:
Some subset of HDD / SSD health indicators is related not only with HDD / SSD itself but also with hardware environment (computer, ports, cables, power supply, drive and ambient temperature and (sometimes even) electrical noise).
SSDs and especially HDDs could be sensitive to power supply level, and high performance 7200+ RPM HDDs could be very sensitive to power supply level. In the case of HDDs: #3 “Spin-Up Time” is mostly affected by power supply health indicator. Health indicator “Spin-Up Time” reports average time (in milliseconds or seconds) of spindle spin-up (from 0 rpm to fully operational). Spin-up generally occurs at the very beginning of the computer boot process. However, most modern computers have the ability to stop a drive while the machine is already running as a means of energy conservation or noise reduction. Fluctuation of “Spin-Up Time” indicator usually means that drive have not enough power supply or has not optimal temperature conditions or both. Typical issue for 3.5-inch hard drives (especially 7200 rpm) connected via USB.
Quality of data cables affects health indicator #199 “(UDMA) CRC Error Count”.
Temperature, vibration level or electrical noise conditions could affect the following health indicators (SMART attributes):
- #1 (Raw) Read Error Rate
- #2 Throughput Performance
- #3 Spin-Up Time
- #13 Soft Read Error Rate
- #195 Hardware ECC Recovered
- #199 (UDMA) CRC Error Count
- #201 Soft Read Error Rate
- some other vendor-specific health indicators.
High temperatures could trigger thermal throttling and affect the performance of SSDs.
SSD results could be affected by internal firmware activities related to garbage collection and self-recovery routines. For example, some Intel SSDs could report some strange results when its firmware performs garbage collection routines.
Results may differ due to:
1) Some subset of HDD / SSD health indicators is related not only with HDD / SSD itself but also with hardware environment (computer, ports, cables, power supply, drive and ambient temperature and (sometimes even) electrical noise).
SSDs and especially HDDs could be sensitive to power supply level, and high performance 7200+ RPM HDDs could be very sensitive to power supply level. In the case of HDDs: #3 “Spin-Up Time” is mostly affected by power supply health indicator. Health indicator “Spin-Up Time” reports average time (in milliseconds or seconds) of spindle spin-up (from 0 rpm to fully operational). Spin-up generally occurs at the very beginning of the computer boot process. However, most modern computers have the ability to stop a drive while the machine is already running as a means of energy conservation or noise reduction. Fluctuation of “Spin-Up Time” indicator usually means that drive have not enough power supply or has not optimal temperature conditions or both.
Quality of data cables affects health indicator #199 “(UDMA) CRC Error Count”.
Temperature, vibration level or electrical noise conditions could affect the following health indicators (SMART attributes):
- #1 (Raw) Read Error Rate
- #2 Throughput Performance
- #3 Spin-Up Time
- #13 Soft Read Error Rate
- #195 Hardware ECC Recovered
- #199 (UDMA) CRC Error Count
- #201 Soft Read Error Rate
- some other vendor-specific health indicators.
High temperatures could trigger thermal throttling and affect the performance of SSDs.
SSD results could be affected by internal firmware activities related to garbage collection and self-recovery routines. For example, some Intel SSDs could report some strange results when its firmware performs garbage collection routines.
2) DriveDx evaluates drive health status based on the next criteria:
- drive’s built-in S.M.A.R.T. status
- SMART attributes statistically closely related to HDD or SSD failures
- health indicators (SMART attributes) proximity to threshold
- measurements history
The last one (measurements history) also could be a cause of different results on multiple computers for the same drive. The more measurement data (history) DriveDx has, the more accurate the results. This is especially could be important in case if the drive has some undocumented proprietary (vendor-specific) health indicators (S.M.A.R.T. attributes). For such health indicators, DriveDx uses heuristics based on measurement history for the detection of a possible range of min/max values. The more measurement history DriveDx has – the more precise its results.
Health warnings & alerts
You can suppress drive health warnings/alerts in DriveDx (not recommended but possible). These option is for advanced users only!
Every drive health warning/alert is triggered by one or more health indicator warning/alert event(s).
You can suppress health indicator warnings/alerts in DriveDx. Not recommended in general, but sometimes could be useful, for example if you replace the data cable and need to suppress “UDMA CRC Error Count” warning. These option is for advanced users only!
- Click on health indicator raw value, raw value information popup window will open,
- In the opened popup window click button “Suppress Current Alert”.
You can ignore health indicator rating changes in DriveDx. Not recommended in general, but sometimes it could be useful if you want to suppress health rating related alerts for this health indicator and if you want this health indicator not to be taken into account when calculating drive Overall Health Rating, Overall Performance Rating, and SSD Lifetime Left Indicator. This option is for advanced users only!
- Click on health indicator rating bar or rating value, information popup window will open,
- In the opened popup window click button “Ignore All Rating Changes”.
If you have suppressed warnings/alerts but want revert them back:
- Right click on drive on the left sidebar, context menu will open,
- In the context menu choose command “Reset raw value alert settings to defaults”.
External USB/FireWire drives support
The latest Mac computers (Apple Silicon and Intel with the T2 security chip) have a “Secure Boot” security feature that controls the system startup/boot process. These models include:
- All Mac models since 2020 (Apple Silicon)
- iMac Pro (has T2 security chip)
- iMac 2020 (has T2 security chip)
- Mac mini 2018 – 2019 (has T2 security chip)
- MacBook Air 2018 – 2019 (has T2 security chip)
- MacBook Pro 2018 – 2019 (has T2 security chip)
- Mac Pro 2019 (has T2 security chip)
Problem:
macOS does not load any non-Apple drivers during the startup process. Therefore, if the external drive was
connected before or during system boot, macOS will not load a third-party driver for it.
- [for any macOS version]
after the end of the system startup, physically disconnect (unplug) the external USB drive(s) and connect back. This will force macOS to load the driver for the newly connected drive(s). Then restart DriveDx. - [for macOS versions prior to macOS 11 (Big Sur)]
switch “Secure Boot” settings to “No Security”. Learn more in the Apple documentation - If after the above steps the drives are still not supported – please follow our troubleshooting instructions
macOS 10.13+ introduced security feature that requires user approval before loading newly-installed third-party kernel extensions (drivers). When a request is made to load a driver that the user has not yet approved, the load request is denied.
Operating procedure. When a request is made to load a driver that the user has not yet approved – the load request is denied and:
- macOS presents the alert “System Extension Blocked”,
- User must approve the driver in “System Preferences > Security & Privacy”. Click the button “Allow” at the bottom right, please see screenshot from Apple documentaion
- This approval UI is only present in the Security & Privacy preferences pane for 30 minutes after the alert. Until the user approves the driver, future load attempts will cause the approval UI to reappear but will not trigger another user alert.
MagicPrefs, BetterTouchTool, any other mouse/touchpad tweakers or any other tools that can capture mouse clicks must be disabled.
macOS security system requires “Allow” button to be able to pressed only by user directly, any mouse clicks “proxied” by 3rd party software (by any app that captures mouse) will be blocked by system.If you want to learn more – please check official documentation from Apple .
Troubleshooting tips if you installed the SAT SMART Driver (special driver to allow your Mac to receive S.M.A.R.T. data from external drives), but DriveDx still reports “SMART Status: not supported” for the specific external drive(s) you are using:
- Physically reconnect all your external USB/FireWire drives.
- Reboot your computer after driver installation (Note: sometimes macOS needs multiple reboots to update its driver cache).
- (!!) Manually physically reconnect all your external USB/FireWire drives again.
- Try to rebuild/refresh system kernel extension cache (can be especially helpful after any macOS upgrades).
- macOS does not allow multiple drivers for the drive at the same time, so if you installed any drive vendor-specific driver – uninstall it (for example Samsung driver for Samsung Portable T5/T7 SSDs automatically comes with Samsung Magician tool installation).
- Check our list of known drives compatibility issues .
- Check if your external drive enclosure controller is SAT (SCSI ATA Translation) capable. You can find list of devices that supports SAT technology here .
- Even if drive enclosure is SAT capable, current version of SAT SMART Driver may not support it. In this case you could submit an issue to developer .
- Use another drive enclosure model.
- Connect via Thunderbolt.
MagicPrefs, BetterTouchTool, any other mouse/touchpad tweakers or any other tools that can capture mouse clicks must be disabled.
macOS security system requires “Allow” button to be able to pressed only by user directly, any mouse clicks “proxied” by 3rd party software (by any app that captures mouse) will be blocked by system.All third-party drivers (kernel extensions) must be updated due the introduction by Apple of new security policies starting with macOS El Capitan (10.11). If you have previously installed driver for external drive diagnostic support – you must update it.
You must uninstall previous driver version and restart your Mac before driver reinstallation (update).
- Update DriveX to recent version (menu “DriveDx > Check For Updates…”) or download it from our website.
- Uninstall previous driver version – type in Terminal.app next commands:
sudo rm -r /System/Library/Extensions/SATSMARTDriver.kext sudo rm -r /System/Library/Extensions/SATSMARTLib.pluginNote: if you upgraded to macOS Catalina 10.15 – use next commands:sudo rm -r /Library/Extensions/SATSMARTDriver.kext sudo rm -r /Library/Extensions/SATSMARTLib.plugin - Restart your Mac.
- Start driver installation from DriveDx.
- Restart your Mac.
When the macOS boots – it saves all currently used kernel extensions (drivers) into a cache for faster booting next time – and if you move things around in “/Library/Extensions/” and “/System/Library/Extensions/” – you won’t see those changes reflected until the caches are rebuilt. Also, due to bugs in some versions of macOS – kext cache becomes outdated or corrupted, especially in the case of system upgrades. Manual kext cache rebuild could fix many troubles with drivers (kernel extensions).
Type in the terminal following commands:
sudo kextcache -i /sudo kextcache -system-caches
Currently, there is no NVMe SMART over USB drivers for macOS. macOS does not support this and there are no third-party drivers (kernel extensions). Moreover, currently, there is no official specification for NVMe SMART over USB from NVM Express Workgroup. Currently only vendor-specific workarounds available like JMicron and AMedia but there is no common standard.
Some examples of external USB SSDs that are internally based on NVMe SSDs: Samsung Portable T7 SSD, Samsung Portable T7 Touch SSD, Crucial X8 Portable SSD, Sandisk Extreme SSD, Sandisk Extreme Pro SSD.
- Type in Terminal.app next commands –
on macOS 10.11+ or later:sudo rm -r /Library/Extensions/SATSMARTDriver.kext sudo rm -r /Library/Extensions/SATSMARTLib.pluginon macOS 10.6 – 10.10:sudo rm -r /System/Library/Extensions/SATSMARTDriver.kext sudo rm -r /System/Library/Extensions/SATSMARTLib.plugin - Restart your Mac.
If possible, we recommend that you do not use external drives from manufacturers that are fully integrated (soldered) to the enclosure (box) and do not have a standard SATA connector. Because winning only marginally in compactness you lose in reliability. Benefits of a separate external enclosure (box) or external dock:
- You will not have any problems accessing your data – if something happens with the USB connector or USB controller integrated by the manufacturer into an external drive. In the case of a separate external enclosure (box) for HDDs/SSDs, you simply remove the (standard!) HDD/SSD from it and insert it into another enclosure (box) or external dock station.
- You will not have problems with compatibility with future versions of macOS and SAT-SMART-driver versions, in case of incompatibility just use a different model, separate external enclosures (boxes) are very cheap and usually cost 1-10 USD.
Starting with macOS 10.13.6 (High Sierra) – macOS components are prohibited from using any third-party drivers, libraries, and extensions (even those notarized by Apple). This is part of macOS System Integrity Protection and Hardened Runtime. Thus, Disk Utility does not use (can’t use) the SAT SMART driver, and as a result, cannot read SMART from external USB drivers. (Note: In the terminal or console, you will see an error message something like “… ‘SATSMARTLib’ not valid for use in process: mapping process is a platform binary, but mapped file is not”.) The wall of Apple’s walled garden is getting higher and higher.
Drive Self-tests
Q: Is an HDD full self-test includes a full disk surface scan [for bad blocks]?
A: Yes. Full self-test of HDD includes full disk surface scan for bad blocks/sectors, it takes several hours, depending on HDD read/write speed and its size. In the case of surface scan error, it will report the address of the first sector (LBA) where read (or write) error occurred.
“Self-test” means that drive performs self-diagnostic routines (usually by user request). Drive’s firmware has a subset of special internal diagnostic routines. The drive’s vendor specially designed and implemented these tests in the drive firmware. SMART self-test could update some SMART data (health indicators, statistics). Self-tests are a nice addition to the diagnostic but not a mandatory feature as modern drives can perform most of the diagnostics on the fly when working. Moreover, NVMe-based SSD currently doesn’t have/support self-tests. (Wikipedia about SMART self-tests )
Self-tests have low priority and may be interrupted by higher priority commands, reset, or a standby command sent to the drive after some time of I/O inactivity. Many USB bridges do this. Most common causes of aborted self-test are:
- macOS (aggresive) power management. Self-testing is a completely internal activity inside drive,
OS knows nothing about it and may decide that drive is idle and should be put to sleep state.
Recent macOS versions:
Tweak macOS “Battery” settings. Uncheck “Prevent computer from sleeping automatically when the display is off”.Older macOS versions:
Tweak macOS “Energy Saver” settings before starting drive long self-test. Go to menu “System Preferences… > Energy Saver”. Uncheck “Put the hard disk to sleep when possible” option, and if you are not planning any activity with your Mac during self-test – also it will be a good idea to disable “Computer sleep” setting too (or otherwise self-test will be interrupted when system goes to sleep). - Drive is under heavy load. All self-diagnostic routines usually have the lowest priority and
could be interrupted if drive is under heavy loaded. Try to (re)start self-test when drive is idle.
- Do not connect the drive through multiple USB bridges (hubs), connect the drive enclosure directly to the Mac.
- Low-quality and buggy external drive enclosure (controller). Try to use another enclosure.
- Buggy drive firmware. For example some Intel
SSDs
Update drive firmware.
Self-test can be aborted if 2 or more SMART check programs are running simultaneously, list of possible apps: DriveGenius (with enabled DrivePulse plug-in), iStat Menu, etc.
Q: Is it possible to reset/clear the self test logs?
A: Drive firmware stores self-test log inside the drive itself. Only drive full secure erase could reset the internal drive state on many drive models.
Hardware support and issues
The driver of Samsung Portable SSD T5 is not compatible with SATSMARTDriver. macOS does not allow multiple drivers for the drive at the same time.
Please check user manual of Samsung T5 SSD – page 6. Here is quote from user manual:
Samsung Portable SSD T7 / T7 Touch is NVMe-based SSD internally, so it is not compatible with SAT SMART Driver. SAT is shortened for “SCSI to (S)ATA Translation”, it is for SATA-drives, not NVMe/PCI-drives. For more information about NVMe SMART over USB – please check this article in our FAQ.
Sandisk Extreme (Pro) SSD is NVMe-based SSD internally, so it is not compatible with SAT SMART Driver. SAT is shortened for “SCSI to (S)ATA Translation”, it is for SATA-drives, not NVMe/PCI-drives. For more information about NVMe SMART over USB – please check this article in our FAQ.
Crucial X8 Portable SSD is NVMe-based SSD internally, so it is not compatible with SAT SMART Driver. SAT is shortened for “SCSI to (S)ATA Translation”, it is for SATA-drives, not NVMe/PCI-drives. For more information about NVMe SMART over USB – please check this article in our FAQ.
SD Cards should be S.M.A.R.T. capable. As a rule, the cheapest cards do not support SMART; the more expensive and professional the card, the more likely it is to support SMART technology. (Usually expensive CFast Cards are SMART capable.)
Note: if you are using external USB card readers etc. – you need to install USB SAT SMART driver
CFast media (like any other drive type) should be S.M.A.R.T. capable. As a rule, the cheapest cards do not support SMART; the more expensive and professional the card, the more likely it is to support SMART technology.
Note: if you are using external USB card readers etc. – you need to install USB SAT SMART driver
Known drive firmware issues
Crucial M4 and RealSSD C400 SSDs with firmware earlier than 70H / 07M could become unresponsive after 5184 hours of Power-on time. The drive will recover after a power cycle, however, this failure will repeat once per hour after reaching this point.