Erasing your disk: For most reasons to erase, including when reformatting a disk or selling, giving away, or trading in your Mac, you should erase your entire disk.
Set your bootable USB as your startup disk for the next boot in “Apple Menu - System Preferences - Startup Disk,” then click “Restart” to reboot your Mac. Your Mac will reboot from the USB instead of your default startup disk. Alternatively, you can also use the Startup Manager to select your boot drive when you start macOS. Restart your Mac and hold down the Option key to enter into the boot selection. If you have a 2015 or newer MacBook or a 2016 or newer MacBook Pro, you may need Apple’s USB to USB-C adapter. This will allow you to connect a storage device that uses a USB type-A connector. World of tanks for mac how to.
The macOS installer file is large with approximate size of 6 to 10GB depending upon the. In the sidebar, select a disk or volume, then click the First Aid button. If Disk Utility tells you the disk is about to fail, back up your data and replace the disk—you can’t repair it. Otherwise, continue to the next step. Click Run, then click Continue. If Disk Utility reports that the disk appears to be OK or has been repaired, you’re done.
Erasing a volume on your disk: In other cases, such as when your disk contains multiple volumes (or partitions) and you don't want to erase them all, you can erase specific volumes on the disk.
Erasing a disk or volume permanently deletes all of its files. Before continuing, make sure that you have a backup of any files that you want to keep.
How to erase your disk
- Start up from macOS Recovery. Then select Disk Utility from the Utilities window and click Continue.
If you're not erasing the disk your Mac started up from, you don't need to start up from macOS Recovery: just open Disk Utility from the Utilities folder of your Applications folder. - Choose View > Show All Devices from the menu bar in Disk Utility. The sidebar now shows your disks (devices) and any containers and volumes within them. The disk your Mac started up from is at the top of the list. In this example, Apple SSD is the startup disk:
- Select the disk that you want to erase. Don't see your disk?
- Click Erase, then complete these items:
- Name: Type the name that you want the disk to have after you erase it.
- Format: Choose APFS or Mac OS Extended (Journaled). Disk Utility shows a compatible format by default.
- Scheme: Choose GUID Partition Map.
- Click Erase to begin erasing your disk and every container and volume within it. You might be asked to enter your Apple ID. Forgot your Apple ID?
- When done, quit Disk Utility.
- If you want your Mac to be able to start up from the disk you erased, reinstall macOS on the disk.
How to erase a volume on your disk
- Start up from macOS Recovery. Then select Disk Utility from the Utilities window and click Continue.
If you're not erasing the volume your Mac started up from, you don't need to start up from macOS Recovery: just open Disk Utility from the Utilities folder of your Applications folder. - In the sidebar of Disk Utility, select the volume that you want to erase. The volume your Mac started up from is named Macintosh HD, unless you changed its name. Don't see your volume?
- Click Erase, then complete these items:
- Name: Type the name that you want the volume to have after you erase it.
- Format: Choose APFS or Mac OS Extended (Journaled). Disk Utility shows a compatible format by default.
- If you see an Erase Volume Group button, the volume you selected is part of a volume group. In that case, you should erase the volume group. Otherwise, click Erase to erase just the selected volume. You might be asked to enter your Apple ID. Forgot your Apple ID?
- When done, quit Disk Utility.
- If you want your Mac to be able to start up from the volume you erased, reinstall macOS on that volume.
Reasons to erase
You can erase at any time, including in circumstances such as these:
- You want to permanently erase all content from your Mac and restore it to factory settings. This is one of the final steps before selling, giving away, or trading in your Mac.
- You're changing the format of a disk, such as from a PC format (FAT, ExFAT, or NTFS) to a Mac format (APFS or Mac OS Extended).
- You received a message that your disk isn't readable by this computer.
- You're trying to resolve a disk issue that Disk Utility can't repair.
- The macOS installer doesn't see your disk or can't install on it. For example, the installer might say that your disk isn't formatted correctly, isn't using a GUID partition scheme, contains a newer version of the operating system, or can't be used to start up your computer.
- The macOS installer says that you may not install to this volume because it is part of an Apple RAID.
About APFS and Mac OS Extended
Disk Utility in macOS High Sierra or later can erase using either the newer APFS (Apple File System) format or the older Mac OS Extended format, and it automatically chooses a compatible format for you.
How to choose between APFS and Mac OS Extended
Disk Utility tries to detect the type of storage and show the appropriate format in the Format menu. If it can't, it chooses Mac OS Extended, which works with all versions of macOS. If you want to change the format, answer these questions:
- Are you formatting the disk that came built into your Mac?
If the built-in disk came APFS-formatted, Disk Utility suggests APFS. Don't change it to Mac OS Extended. - Are you about to install macOS High Sierra or later for the first time on the disk?
If you need to erase your disk before installing High Sierra or later for the first time on that disk, choose Mac OS Extended (Journaled). During installation, the macOS installer decides whether to automatically convert to APFS—without erasing your files. - Are you preparing a Time Machine backup disk or bootable installer?
Choose Mac OS Extended (Journaled) for any disk that you plan to use as a Time Machine backup disk or as a bootable installer. - Will you be using the disk with another Mac?
If the other Mac isn't using macOS High Sierra or later, choose Mac OS Extended (Journaled). Earlier versions of macOS don't work with APFS-formatted volumes.
How to identify the format currently in use
If you want to know which format is currently in use, use any of these methods:
- Select the volume in the Disk Utility sidebar, then check the information shown on the right. For more detail, choose File > Get Info from the Disk Utility menu bar.
- Open System Information and select Storage in the sidebar. The File System column on the right shows the format of each volume.
- Select the volume in the Finder, then choose File > Get Info from the menu bar. The Get Info window shows the Format of that volume.
If your disk or volume doesn't appear, or the erase fails
- Shut down your Mac, then unplug all nonessential devices from your Mac.
- If you're erasing an external drive, make sure that it's connected directly to your Mac using a cable that you know is good. Then turn the drive off and back on.
- If your disk or volume still doesn't appear in Disk Utility, or Disk Utility reports that the erase process failed, your disk or Mac might need service. If you need help, please contact Apple Support.
Learn more
- If you can't start up from macOS Recovery, you can use a different startup disk instead.
- If Disk Utility shows a Security Options button in the Erase window, you can click that button to choose between a faster (but less secure) erase and a slower (but more secure) erase. Some older versions of Disk Utility offer the option to zero all data instead. These secure-erase options aren't offered or needed for solid-state drives (SSDs) and flash storage.
![Create mac recovery usb windows Create mac recovery usb windows](https://www.dev2qa.com/wp-content/uploads/2018/09/mac-os-use-disk-utility-to-change-usb-disk-format.png)
Summary: Don't know how to fix when USB flash drive is not mounting on Mac? Try these 4 solutions in this page and use iBoysoft Data Recovery for Mac to recover lost data necessarily.
- Table of contents
- 1. Why the USB flash drive is not mounting on Mac?
- 2. How to fix/repair “USB flash drive not mounting” issue on Mac?
- 3. How to recover lost data from unmounted/unrecognizable USB flash drives?
When I plugged in my USB flash drive on macOS High Sierra, I can't see it in Finder or on the Desktop. So, I went to Disk Utility, it was there. But the USB flash drive was grayed out in Disk Utility and I could not mount it. How can I fix/repair USB flash drive not mounting issue on Mac?
It is user-friendly that Mac will automatically mount the inserted USB flash drives. However, if the USB flash drive is not mounted on Mac, you will lose access to the USB flash drive as well as to the data stored on it. But don't worry, this page talks about the reasons for this issue, and how to fix 'USB flash drive not mounting on Mac' without data loss even if external hard drive is not showing up on Mac.
Why the USB flash drive is not mounting on Mac?
What makes the hard drive not working problems like USB flash drive unmounted on Mac can be various. This is because that this external drive is connected to the Mac computer through USB cable, USB port and many other components. The possible reasons for this issue include:
- Faulty connections like broken cable and wobbly USB port
- File system errors, volume header corruptions, etc. in the USB flash drive
- Disk Utility failure, log file corruption, OS malfunction on this Mac
- Physical damage and other factors
How to fix/repair USB flash drive not mounting issue on Mac?
No matter what results in unmountable USB flash drive, it's urgent to fix/repair USB flash drive not mounting issue on Mac. Here are 4 solutions to this unmounted USB flash drive issue according to different causes, you can check them one by one.
Solution 1: Check the USB flash drive in System Information
If you plug this USB flash drive into your Mac computer but get no sign that this drive is mounting on Mac, you can check System Information to see if this USB flash drive is showing up.
- Step 1: Go to Utilities and choose System Information.
- Step 2: Double-click on its icon to open it and choose USB in the left sidebar.
- Step 3: Check if your USB flash drive is detected by the system in the right box.
If your USB flash drive is not showing up in the right box, you can try to re-plug it, or change another USB port and cable to connect it.
Solution 2: Check the Finder Preferences
Sometimes, you just can't find the USB flash drive in Finder and on the desktop, but actually, it is mounted on your Mac and just not showing up. Check the Finder Preferences and see if it will appear.
- Step 1: Click Finder and choose Preferences in the top menu bar.
- Step 2: Check External Disks in General tab so that the USB flash drive can be shown on the desktop.
- Step 3: Go to Sidebar and check External disks so that they can be located in Finder.
Solution 3: Check and repair this USB flash drive with Disk Utility
If you still can't access your USB flash drive thereafter, you can go to Disk Utility which is a built-in utility to fix disk problems. If it is greyed out in Disk Utility, you can manually mount this USB flash drive.
- Step 1: Go > Utilities > Disk Utility.
- Step 2: Click on View option and choose 'Show all devices'.
- Step 3: Click on the name of your USB flash drive.
- Step 4: Select Mount in the upper menu bar.
If the Mount button is greyed out and you can't mount this USB flash drive manually, then there could be some disk errors. Fortunately, you can use First Aid in Disk Utility to repair this unmountable USB flash drive.
- Step 1: Launch Disk Utility.
- Step 2: Choose the grayed-out USB flash drive.
- Step 3: Select First Aid in the top center and click Run.
Solution 4: Fix the unmountable USB flash drive by reformatting
However, if Disk Utility fails to repair this external drive because of serious file system corruption, you can only fix this by reformatting. The thing you need to keep in mind is that reformatting will erase all files on this USB flash drive, which means, you need to make sure an existing file backup. Or you can recover lost data from the unmountable USB flash drive before you fix the USB flash drive not mounting issue on Mac by reformatting.
How to recover lost data from unmounted/unrecognizable USB flash drives?
Can't open the unmountable USB flash drive but don't want to lose data? You can still get your files back with USB flash drive data recovery software before you reformat this drive.
As one of the most professional USB data recovery software, iBoysoft Data Recovery for Mac is highly recommended. It can recover lost data from unmountable, unreadable, and corrupted USB flash drive, recover deleted/lost files from emptied Mac trash. Moreover, this software performs well in recovering data from hard drives, external hard drives, flash drives, USB sticks, SD cards, and other storage devices. Data recovery is allowed on macOS 10.14/10.13/10.12 and Mac OS X 10.11/10.10/10.9/10.8/10.7.
Step 1: Recover lost data from unmountable USB flash drive with Mac data recovery software
- Step 1: Download and install iBoysoft Data Recovery for Mac on your Mac.
- Step 2: Connect your USB flash drive to the Mac and launch iBoysoft Data Recovery for Mac.
- Step 3: Select the unmountable USB flash drive and click 'Next' button to scan all lost files.
- Step 4: Preview the scanning results by double-clicking, choose files that you want to recover, and click 'Recover' button to get lost data back.
Format Usb Disk Mac
Note: In case you lose the recovered files again in the next reformatting step, you'd better save these files to another reliable drive.
Usb Disk Security For Mac
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Step 2: Reformatting this USB flash drive without data loss
After recovering data from this unmountable USB flash drive, you can reformat this USB flash drive without worrying about losing anything important.
- Step 1: Go > Utilities > Disk Utility.
- Step 2: Click the icon of unmountable USB flash drive on the left part of the window.
- Step 3: Click the Erase button on the top of the Disk Utility window.
- Step 4: Complete the related information(name, format, scheme), then click Erase button.
When the process finished successfully, your USB flash drive will be mountable on the Mac computer again. But the case is, no matter how powerful USB flash drive data recovery software is, the best way to recover files from external drives is to recover them from backups. So, remember to duplicate your files this time.
You may also want to know:
Create Mac Os Recovery Usb
HSD not mounting or seen in Disk Utility? Tutorial to fix SD card not mounting on Mac and recover lost data from unmountable SD card on macOS.