What is a Mac Boot Disk | Accidentally Deleted Mac Boot Disk [Fixed]

What is a Mac Startup Disk? On a Mac, the startup disk is the hard drive or solid-state drive that your computer uses to boot up the operating system (OS). When you turn on your Mac, it loads system files from the startup disk, allowing you to access various applications and features. Typically, the main hard drive with macOS installed is the Mac's startup disk. However, you can set another available disk as the startup disk for alternative booting purposes. Knowing how to select and manage your startup disk is crucial, especially if you need to start your Mac in Recovery Mode or from an external drive. Additionally, if your startup disk runs out of space, it can affect your Mac's performance, making it necessary to regularly clean and optimize your storage.

A Mac startup disk, also known as a boot disk, is the volume on which the macOS and applications are installed. The Mac startup disk plays an important part in the entire operation. If there is no startup disk on Mac or the startup disk is damaged, your Mac won't be able to start up or run.

The Mac startup disk is the built-in hard drive of your Mac, named "Macintosh HD." If you have only one internal hard drive, this is your Mac's startup disk, and your Mac will automatically start up from it.

If you have two or more internal disks, you can choose to boot from a specific one, especially if your Mac won't start up, or if you don't have a startup disk on your Mac.

How to Find the Boot Disk on a Mac

Using the Disk Utility, you can divide a disk into multiple sections called partitions, volumes, or containers to organize and manage your disk space.

If you're not sure which disk is your Mac's startup disk, follow these steps:

Step 1: Choose Apple menu > System Preferences.

Step 2: Click on “General” in the sidebar.

Step 3: Click on "Startup Disk" on the right.

You can see which disk is being used as the boot disk.

How to Change the Startup Disk on a Mac

Sometimes, you may have an issue where your Mac doesn't have a startup disk. There are several ways to view the startup disk, but if none of them work, it's time to change the startup disk on your Mac.

Apple lets you change your Mac's startup disk to a network volume, an external hard drive, or a USB flash drive.

If your default startup disk is damaged, it's time to change your Mac's startup disk. There are two effective ways to change your Mac's startup disk:

Change the Mac Startup Disk Using Startup Manager Change the Mac Startup Disk in System Preferences

If you're a user searching for how to change the startup disk on your Mac, you've come to the right place. This article will introduce two practical methods to change the startup disk on your Mac with simple steps.

There are 2 ways to change startup disk on Mac.

After changing the startup disk on your Mac, you can set the default startup disk on macOS Ventura, macOS Monterey, macOS Big Sur, and so on.

Please share this article on social media so you can read it later.

Accidentally Deleted Boot Disk, What to Do?

When your Mac encounters "No Boot Disk on Mac" or "Boot Disk Missing/Not Showing on Mac" errors after accidental deletion, you can refer to the following solutions to address these issues:

Solution 1: Repair the startup disk in macOS Recovery Mode

The traditional way to open Disk Utility is by opening the Applications folder and selecting Utilities, but this time you'll be accessing Disk Utility from Recovery Mode.

Many MacBook users may encounter the “MacBook Pro boot disk missing” error, for which they are advised to press Command + R or hold down the option/alt key to boot to the recovery volume, and then run Disk Utility to verify or repair disk and repair permissions until no errors are found.

Another way to think about this problem is:

Step 1: Turn off your MacBook Pro, then turn it on and hold down Command-Option-P-R. Release the keys when you hear the startup sound three times.

Step 2: Plug the MagSafe Power Adapter into a power outlet. If it wasn't connected, plug it into your MacBook Pro as well.

Step 3: Hold down the "Shift," "Control," and "Option" keys on the built-in keyboard, along with the Power button.

Step 4: Release all keys and the Power button at the same time.

Step 5 Press the Power button to turn on your MacBook Pro.

Step 6: Restart and hold down the D key to initiate Hardware Test. Follow the on-screen instructions on the MacBook Pro.

When booted from the outside, use the Go menu to open Utilities. Launch Disk Utility and look for any sign of your internal drive in the list on the left. If you see it, look for First Aid and try running it on the disk.

Solution 2: Make the startup disk appear in Disk Utility

Disk Utility can check and repair any connected disk. If your startup disk doesn't appear in Disk Utility, how can you repair it?

Solution 3: Reset the NVRAM to Fix the Issue of Missing Startup Disk

Resetting the NVRAM (Non-Volatile Random-Access Memory) might help. As you know, the NVRAM can store settings for the startup disk selection, among other things.

You can find detailed information and steps for Solutions 1-3 in the following article:

Fix Mac No Startup Disk Without Data Loss

No startup disk issue happens on macOS Ventura, Monterey, Big Sur, Catalina, Mojave, and major macOS updates! Below are some ways to fix the startup disk error and recover data with tools.

Solution 4: Recover Data from Mac Boot Disk

Once the no bootable disk issue is resolved, your boot disk will show up on your Mac. However, you may find some important files missing, meaning that some data has been lost; if you don't have a full backup of your boot disk, it's recommended to use a tool like the Data Recovery Wizard for Mac to recover your data – it can help you retrieve your files even when the built-in startup disk is damaged.

This top-notch recovery utility can retrieve files lost under various circumstances, including undeleting files on Mac, whether it's an individual Office Word document or a bulk of pictures stored on your Mac, regardless of their size.

This professional tool is regarded as the best Mac data retrieval software that helps you recover accidentally deleted files, such as any lost data from emptying trash on Mac, in 3 simple steps.

Step 1: Search for the lost files on your Mac's startup disk.

Step 2: Review the scan results.

Step 3: Select the files you wish to recover.

How to Clean Up Your Mac's Startup Disk

When your Mac alerts you that your “disk space is running low,” it's usually referring to your startup disk. This means that your files, your macOS, and all the other apps you've installed on your Mac – as well as documents, movies, music, downloads, and more – are likely stored on this disk.

Your startup disk is almost full.

How to Check Available Space on Your Mac's Startup Disk

Even if your Mac hasn't warned you that your startup disk is running low on space, it's a good idea to check regularly how much room you have left so you can head off problems.

To see how much free space is available on your Mac's startup disk, follow these steps:

Step 1: Open a Finder window, and select your Mac's startup disk in the sidebar under Locations.

2. Click “File” > “Get Info,” and then click the downward-pointing arrow under “Summary.”

Hover over the chart to see how much space each category uses. Hover over the white area on the right to see how much storage is still available.

Ideally, you should have about 20 GB of storage space free.

How to Clean Up Your Mac's Startup Disk

With a clear picture of how much space is left on your Mac startup disk and what types of files are taking up your storage, it's time to clear system storage to free up space on your startup disk.

Here are some of the most effective ways to free up space on your boot drive:

• Empty the Trash
• Remove Time Machine Snapshots
• Eliminate Unnecessary iOS Backups
• Delete Cache Files in Library
• Update macOS Version

Conclusion

The Mac startup disk, also known as the boot disk, is the volume on which the operating system and apps are installed. It's an essential part of how your Mac functions. You can change your Mac startup disk using the Startup Manager or System Preferences.

You can free up space on your Mac's startup disk by emptying the Trash, removing Time Machine snapshots, deleting unnecessary iOS backups, eliminating cache files in Library, or updating your macOS version.