当您将外部硬盘驱动器或SSD连接到Mac时，您希望它会自动安装并立即显示在桌面上。但是，磁盘错误、USB集线器、电缆故障以及许多其他原因可能会阻止这种情况的发生。
因此，如果您在Mac(Mac)上无法显示外部硬盘驱动器时遇到问题，请通过以下修复程序解决问题。本故障排除指南也适用于 USB 闪存驱动器。
检查您的桌面首选项
您的外部驱动器是否出现在Finder中但拒绝出现在桌面上？这很容易解决。您只需要激活桌面首选项中的特定设置。
1. 选择桌面或打开Finder。
2.在菜单栏上选择Finder >首选项。(Preferences)
3. 在常规选项卡下，选中(General)外部磁盘(External disks)旁边的框。
重新启动查找器
如果驱动器无法显示在 Mac 的桌面或Finder（或两者）上，请尝试强制重启Finder。
1. 转到您的 Mac 桌面，然后按Command + Option + Escape。这应该调用强制退出应用程序(Force Quit Applications )弹出窗口。
2. 选择Finder >重新启动(Relaunch)。
3. 选择重新启动(Relaunch)以确认。
断开并重新连接驱动器
这听起来很明显，但您最终可能会意外弹出外部HDD或SSD。因此，如果您还没有，只需断开驱动器与 Mac 的USB端口的连接，然后尝试重新插入。
重启 Mac
另一个快速修复涉及重新启动您的Mac。这是解决阻止可移动驱动器出现在桌面或Finder上的任何与系统相关的故障的最佳方法。
1.从Mac上断开外置HDD或SSD。
2. 打开Apple菜单并选择重新启动(Restart)。
3. 取消选中重新登录时重新打开窗口(Reopen windows when logging back in)旁边的框，然后选择重新启动(Restart)。
4.等到(Wait)您的Mac完成重新启动进入桌面。
5. 重新连接外部驱动器。
直接连接到 Mac
可移动硬盘驱动器和SSD(SSDs)不适用于外部USB集线器。因此，如果您在Mac(Mac)上使用USB集线器，请尝试将驱动器直接连接到Mac本身的(Mac)USB端口，以确保它获得足够的电量。
注意(Note)：您的可移动驱动器可能还需要额外的电源才能正常运行。如果是这种情况，请确保将任何额外的USB电缆连接到您的Macbook、iMac 或Mac mini（或如果需要，连接到外部电源）。
切换 USB 端口
如果您不使用USB集线器，请尝试将驱动器连接到其他USB或 Thunderbolt 端口。在连接外部驱动器时，防止插入其他USB(USB)外围设备（任何有线键盘和鼠标除外）也是一个好主意。
使用不同的电缆
有故障的USB电缆（或USB-C适配器）是阻止外部驱动器建立正确连接的另一个原因。尝试使用不同的USB连接器并检查是否有所不同。
检查系统信息应用程序
接下来，检查外部驱动器是否出现在 Mac 的系统信息(System Information)应用程序中。
1. 打开 Mac 的Launchpad并选择其他(Other)>系统信息( System Information)。
2. 选择侧边栏上的存储(Storage)。
3. 检查驱动器是否出现在卷(Volume Name)名列下。
如果是这样，您可能正在处理磁盘错误、文件系统损坏或不兼容，或者PRAM或SMC损坏。继续(Continue)进行其余的修复。
在 macOS 中修复外部驱动器
如果外部硬盘或 SSD 出现在系统信息(System Information)中，它也应该出现在磁盘工具(Disk Utility)中。利用这个机会运行急救(run First Aid)。
1.在 Mac 的Launchpad上选择(Launchpad)Other > Disk Utility打开 Disk Utility 。
2.左侧边栏从Mac硬盘切换到外置硬盘。
3. 选择急救(First Aid)按钮。
4. 选择运行(Run)。
5.等待(Wait)磁盘工具(Disk Utility)扫描并解决任何磁盘错误。然后，选择完成(Done)。
或者，尝试将驱动器连接到其他Mac并使用上述说明修复磁盘错误。
修复 Windows 中的磁盘错误
如果外部驱动器使用与 Windows 兼容的文件系统（例如FAT32、ExFAT或NTFS），则使用 PC 修复它可能会获得更好的结果。
1. 将驱动器连接到Windows PC。
2. 打开开始(Start)菜单，键入磁盘管理(Disk Management)，然后选择打开(Open)以启动磁盘管理(Disk Management)小程序。
3. 在卷(Volume)列下查找驱动器。然后，右键单击它并选择Properties。
4. 切换到工具(Tools)选项卡。
5. 在错误检查(Error checking)下，选择检查(Check)。
6. 选择扫描并修复驱动器(Scan and repair drive)。
安装支持软件或驱动程序
除非您安装第三方支持软件或设备驱动程序，否则您的外部驱动器可能无法与 macOS 一起使用。例如，希捷(Seagate)硬盘驱动器和SSD(SSDs)可能需要适用于 macOS 的 Paragon 驱动程序(Paragon Driver for macOS)才能正常工作。查找驱动器的用户手册或制造商网站以获取兼容性信息。
注意(Note)：如果您已经安装了相关的支持软件或设备驱动程序，最好从头开始卸载并重新安装。
重置 NVRAM 或 PRAM
损坏的NVRAM或PRAM（保存系统关键设置（例如时间、日期和启动首选项）的易失性内存）也可以防止外部驱动器出现。如果您使用的是Intel Mac，您可以尝试重置它。
1. 断开外部驱动器。
2. 关闭你的 Mac。
3. 按住Command、Option、P和R并按下电源(Power)按钮。
4. 按住直到您听到两次启动提示音（或当您第二次看到Apple标志时）。
5. 到达 Mac 桌面后重新连接驱动器。
重置 SMC
基于 Intel 的Mac(Macs)的另一个修复涉及SMC重置。SMC （存储管理控制器）是一个子系统，用于管理许多低级活动，例如电源和电池管理。
重置SMC的过程因各种Mac型号而异。查看我们在 Mac 计算机上重置 SMC(resetting the SMC on a Mac computer)的完整指南，了解全面的分步说明。
更新 Mac
您的Mac可能与外部驱动器的文件系统不兼容。例如，运行 macOS Sierra或更早版本的(Sierra)Mac(Macs)不支持APFS 文件系统(APFS file system)。如果可能，请尝试更新或升级操作系统。
如果您使用 macOS High Sierra或更早版本，您可以通过App Store升级您的Mac。在更高版本的 macOS 中，打开Apple菜单并转至关于本机(About This Mac)/系统偏好设置(System Preferences)>软件更新(Software Update )。
擦除外部驱动器
外部驱动器未显示时的最终修复涉及擦除驱动器。您将丢失设备上的所有数据，因此请尽可能尝试将任何文件或文件夹复制到另一台Mac或 PC。或者，使用数据恢复软件(data recovery software)（或联系数据恢复专家）从驱动器中恢复数据。
1. 打开磁盘工具应用程序。
2. 选择侧边栏上的外部驱动器。
3. 选择擦除(Erase)。
4. 将文件系统设置为Mac OS Extended ( HFS+ ) 或APFS (Case-sensitive)。如果您希望驱动器在Windows设备上可读，请选择ExFAT。
5. 选择擦除(Erase)以重新格式化驱动器。
如果外部HDD或SSD继续无法安装，并且其他桌面设备也出现此问题，则您可能正在处理驱动器本身的硬件问题。如果驱动器仍在保修期内，请将驱动器寄回更换。
FIX: External Hard Drive Not Mounting on macOS
When you connect an external hard drive or SSD to your Mac, you expect it to mount automatically and show up on the desktop right away. Hоwever, dіsk errors, USB hubs, faulty cables, and a host of other reasons can preνent that from hаppening.
So if you have trouble with an external hard drive not showing up on Mac, work your way through the fixes below to resolve the problem. This troubleshooting guide also applies to USB flash drives.
Check Your Desktop Preferences
Is your external drive appearing in Finder but refusing to show up on the desktop? That’s an easy fix. You just need to activate a specific setting in your desktop preferences.
1. Select the desktop or open Finder.
2. Select Finder > Preferences on the menu bar.
3. Under the General tab, check the box next to External disks.
Relaunch Finder
If the drive fails to show up on Mac’s desktop or Finder (or both), try force-restarting Finder.
1. Go to your Mac’s desktop and press Command + Option + Escape. That should invoke the Force Quit Applications popup.
2. Select Finder > Relaunch.
3. Select Relaunch to confirm.
Disconnect & Reconnect Drive
This one sounds obvious, but you can end up ejecting your external HDD or SSD by accident. So if you haven’t already, just disconnect the drive from the Mac’s USB port and try plugging it back in again.
Restart Mac
Another quick fix involves restarting your Mac. That’s the best way to resolve any system-related glitches preventing removable drives from showing up on the desktop or Finder.
1. Disconnect the external HDD or SSD from your Mac.
2. Open the Apple menu and select Restart.
3. Uncheck the box next to Reopen windows when logging back in and select Restart.
4. Wait until your Mac finishes rebooting into the desktop.
5. Reconnect the external drive.
Connect Directly to Mac
Removable hard drives and SSDs don’t work well with external USB hubs. So if you use a USB hub on your Mac, try connecting the drive directly to a USB port on the Mac itself to ensure that it receives enough power.
Note: Your removable drive may also require extra power to function by design. If that’s the case, make sure to connect any additional USB cables to your Macbook, iMac, or Mac mini (or to an external power supply if needed).
Switch USB Ports
If you don’t use a USB hub, try connecting the drive to a different USB or thunderbolt port instead. It’s also a good idea to prevent other USB peripherals (aside from any wired keyboards and mice) from being plugged in while having the external drive connected.
Use a Different Cable
A faulty USB cable (or USB-C adapter) is another reason that prevents the external drive from establishing a proper connection. Try using a different USB connector and check if that makes a difference.
Check the System Information App
Next up, check if the external drive appears within your Mac’s System Information app.
1. Open the Mac’s Launchpad and select Other > System Information.
2. Select Storage on the sidebar.
3. Check if the drive appears under the Volume Name column.
If it does, you’re likely dealing with disk errors, a broken or incompatible file system, or a corrupt PRAM or SMC. Continue with the rest of the fixes.
Repair External Drive in macOS
If the external hard disk or SSD shows up in System Information, it should also appear within Disk Utility. Use the opportunity to run First Aid.
1. Open Disk Utility by selecting Other > Disk Utility on the Mac’s Launchpad.
2. Switch from the Mac hard drive to the external drive on the left sidebar.
3. Select the First Aid button.
4. Select Run.
5. Wait until Disk Utility scans for and resolves any disk errors. Then, select Done.
Alternatively, try connecting the drive to a different Mac and use the above instructions to repair disk errors.
Repair Disk Errors in Windows
If the external drive uses a Windows-compatible file system (such as FAT32, ExFAT, or NTFS), you might have better results by repairing it using a PC.
1. Connect the drive to a Windows PC.
2. Open the Start menu, type Disk Management, and select Open to launch the Disk Management applet.
3. Look for the drive under the Volume column. Then, right-click it and select Properties.
4. Switch to the Tools tab.
5. Under Error checking, select Check.
6. Select Scan and repair drive.
Install Support Software or Drivers
Your external drive may not work with macOS unless you install third-party support software or device drivers. For example, Seagate hard disk drives and SSDs may require the Paragon Driver for macOS to work correctly. Look up the drive’s user manual or manufacturer website for compatibility information.
Note: If you’ve already installed the relevant support software or device drivers, it’s best to uninstall and reinstall them from scratch.
Reset NVRAM or PRAM
A corrupt NVRAM or PRAM (volatile memory that holds system-critical settings such as the time, date, and startup preferences) can also prevent external drives from showing up. If you use an Intel Mac, you can try resetting it.
1. Disconnect the external drive.
2. Turn off your Mac.
3. Press and hold the Command, Option, P, and R and press the Power button.
4. Keep holding until you hear the startup chime twice (or when you see the Apple logo for the second time).
5. Reconnect the drive once you reach Mac’s desktop.
Reset SMC
Another fix for Intel-based Macs involves an SMC reset. The SMC (storage management controller) is a sub-system that manages a host of low-level activities such as power and battery management.
The procedure to reset the SMC is different for various Mac models. Check our complete guide to resetting the SMC on a Mac computer for comprehensive step-by-step instructions.
Update Mac
Your Mac may not be compatible with the external drive’s file system. For example, Macs running macOS Sierra or earlier do not support the APFS file system. If possible, try updating or upgrading the operating system.
If you use macOS High Sierra or earlier, you can upgrade your Mac via the App Store. In later versions of macOS, open the Apple menu and go to About This Mac/System Preferences > Software Update instead.
Erase the External Drive
The final fix for when your external drive is not showing up involves erasing the drive. You will lose all data on the device, so try copying any files or folders to another Mac or PC if possible. Or else, use data recovery software (or contact a data recovery specialist) to recover data from the drive.
1. Open the Disk Utility app.
2. Select the external drive on the sidebar.
3. Select Erase.
4. Set the file system to Mac OS Extended (HFS+) or APFS (Case-sensitive). If you want the drive to be readable on Windows devices, select ExFAT.
5. Select Erase to reformat the drive.
If the external HDD or SSD continues to fail to mount and the problem also occurs with other desktop devices as well, you’re likely dealing with hardware issues on the drive itself. Send the drive back for a replacement if it’s still under warranty.
