Knowledge base & Troubleshooting (FAQ)

External drives support on recent Macs with T2 chip – How-To

General

What does DriveDx name stand for?

DriveDx = Drive Diagnostics. Dx is medical shorthand for Diagnostics/Diagnosis in USA and some other countries.

Support for beta versions of macOS

We are not providing official support for Beta-versions of macOS.

Software issues

DriveDx doesn’t show my internal drive(s) – “Drives with S.M.A.R.T. support not found”

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.

App update error: read-only volume

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!
DriveDx doesn’t “launch at login”

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:
Move DriveDx app to the “/Applications” folder using (!) Finder.
IMPORTANT: only Finder removes special “quarantine flag”, but third-party file managers are not!

S.M.A.R.T. data and Health indicators

I changed the USB-cable but DriveDx shows the same “CRC Error Count” warning

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.

By default, DriveDx will stop showing this warning if the number of errors has not increased in the next 48 power-on hours of the drive.

For immediate manual suppressing of this warning please see section How to suppress health indicator warning/alert. Note: if CRC Error Count will increase again in the future – DriveDx will start warning you again.

SSD Power On Hours value is “small”

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.

SSD Power Cycle Count value is “big”

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’”.

SSD Power Cycle Count value is 7 and Power On Hours value is 0 (zero)

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 vs SSD/HDD Power Cycle Count

“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

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
Example
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”.

Drive Overall Health Rating or Overall Performance Rating fluctuation
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.

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.

Differing Results on 2 computers – Same Drive

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

How to suppress drive health warning/alert

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).

To suppress drive health alert you should suppress all health indicator current warnings/alerts. Please see “How to suppress health indicator warning/alert”.
After that, you will be notified only in case of next change of drive health status.
How to suppress health indicator warning/alert

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”.
After that, you will be notified only in case of next change of health indicator status.
How to ignore health indicator rating changes

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”.
How to turn back all suppressed health warnings/alerts

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

External drives support on recent Macs with T2 security chip

Recently released Macs that include an integrated T2 chip include new security feature “Secure Boot” that control system startup/boot process. These models include:

  • iMac Pro
  • iMac 2020 or later
  • Mac mini 2018 or later
  • MacBook Air 2018 or later
  • MacBook Pro 2018 or later
  • Mac Pro 2019 or later

Unfortunately there is a BUG in the mac OS related to “secure boot”:
User needs to always disconnect external drives before starting up. Or otherwise, Apple’s default USB driver will override any 3rd party driver on (secure) boot any time a USB device is attached.

Workaround:
  • try physically disconnect external drives and then connect again.
  • try to physically disconnect external drives before (re)boot.
External drives support on macOS 10.13 and newer

macOS High Sierra 10.13 introduces a new 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 .

Can’t press “Allow” button – “System Preferences > Security” pane is “frozen”
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.
Upgrading from macOS 10.6-10.10 to macOS El Capitan (10.11) or newer

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).
Instructions:
  • 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.plugin
                    
    Note: 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.
External USB/FireWire drive support troubleshooting

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 Apple Disk Utility 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.
  • (For Mac’s with T2 chip) 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 SSD).
  • Try to install another version of driver. Uninstall current driver, download SAT SMART Driver v0.10  Install it.
  • 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.
How to rebuild macOS kernel extensions/driver cache

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
Conflicting drivers (kernel extensions)
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 SSD).
External NVMe (M.2) SSDs support

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.

Our advice – use some Thunderbolt-based enclosure.
How to uninstall SAT SMART Driver
  • 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.plugin
                        
    on macOS 10.6 – 10.10:
     
                        sudo rm -r /System/Library/Extensions/SATSMARTDriver.kext
                        sudo rm -r /System/Library/Extensions/SATSMARTLib.plugin
                        
  • Restart your Mac.
Which model of external drive or external enclosure (box) to choose?

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.
macOS 11 Big Sur support
  • macOS 11 Big Sur will be supported,
  • We are not providing official support for Beta-versions of macOS.

Drive Self-tests

Is an HDD full self-test includes a full disk surface scan?

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 aborted/interrupted by host
Most common causes of aborted self-test are:
  1. Mac OS X 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.
    Tweak Mac OS X “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).
  2. 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.
  3. Buggy drive firmware.
    Update drive firmware.
Self-test completed with “unknown result”

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.

Disable SMART check/monitoring in other apps because they excessively polling drive’s SMART subsystem that leads to unexpected abortion of all SMART-related operations.
Clear/reset list of Self-test results

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

OWC Aura SSD
Health diagnostics of OWC Aura SSDs is not possible because this SSDs don’t support S.M.A.R.T. technology as stated in the official spec , see section “SMART Attributes”.
Samsung Portable T5 SSD

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:

“MacOS only, Samsung Portable SSD driver and some of 3rd party drivers, including SATSMARTDriver are mutually exclusive. If you wish to work with SATSMARTDriver, please remove Samsung Portable SSD driver and install SATSMARTDriver as following instruction.”
CFast Cards support

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 5184 hours power-on time BSOD issue

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.

    Update firmware to version 70H / 07M or newer:
  • Crucial firmware updates official page
  • Micron firmware updates official page
Crucial M500 SSDs long reboot times

New firmware (version M03) resolved potential problem causing long reboot times on some Apple MacBook systems and has improved SMART diagnostic capabilities. Learn more

    Update firmware to version M03 or newer:
  • Crucial firmware updates official page
  • Micron firmware updates official page
Seagate Barracuda 7200.14 firmware update

A firmware update for this drive model is available here .

Seagate Momentus XT HDDs with firmware version prior to SD26 could cause files corruption

Seagate Momentus XT HDDs with firmware prior to SD26 could cause files corruption and system freezes. You can learn more info here .

Critical firmware update for this drive model is available here .

DriveDx is the most advanced drive health diagnostic and monitoring utility!
Requires Mac OS X 10.6+.