Special boot modes for Mac OS. Mac boot modes

The Mac OS X operating system is one of the most stable systems. If you downloaded it, then weeks, or even months, may pass before the next reboot. But sometimes there are situations when some kind of failure occurs, and you need to boot the computer in safe mode or need to boot from an external drive, or simply boot into another OS, for example, Windows, if of course you have it installed.

In this article we will talk about special boot modes for computers running Mac OS, as well as how you can boot into them. To use these methods, you need to hold down the key combinations indicated in each mode as soon as you hear the sound of the operating system loading.

Selecting a boot disk

If you need to boot from an external drive or flash drive, or there are several operating systems installed on your computer and you want to boot into one of them, then you need to hold down the ⌥Option(Alt) key on your keyboard when booting, after which a menu with a disk selection will appear in front of you.

If your iMac or MacBook Pro has an optical CD/DVD drive and you want to boot from it, hold down the C key at startup. In this method, you will bypass the menu with the choice of disks to boot and will immediately start booting from the CD/DVD disc.

Running from a NetBoot image (netboot)

If your Mac cannot boot on its own due to some problem, you can use it in external drive mode by connecting it to another computer with OS X installed via FireWire or Thunderbolt. After which you will have full access to its hard drive and will be able to transfer any information from it. To boot your Mac in Target Disk mode, use the T key.

Running Apple Hardware Test

This boot mode makes it possible to check your computer hardware for possible hardware problems. By pressing the D key during boot, you can run this diagnostic.

This download method, compared to the Apple Hardware Test, makes it possible to find problems directly in the software part of the system. In this mode, only the main functions of the system that are necessary for its operation are loaded, other boot objects are disabled. To boot your computer in Safe Mode, you need to press and hold the ⇧Shift key until a screen with a loading indicator appears.

When using this method, you will be able to watch the boot process on the Mac screen with service messages displayed. This mode is good because if any error occurs during normal loading, you can determine at what stage it appears. You can boot into this mode using the keyboard shortcut ⌘Cmd + V

This mode, like Verbose Mode, is also designed to identify and troubleshoot problems, only when booting into Single User mode, after all service messages are displayed, you will have to work with the command line. Therefore, this method is intended only for experienced users and to use it you need to hold down the key combination ⌘Cmd + S when loading

Resetting NVRAM and PRAM

If you are having problems with the operation of the system or peripheral devices connected to your Mac, then one way to solve the problem is to reset the computer's memory (NVRAM and PRAM), which is stored on the hard drive and is not erased when turned off. This memory stores settings such as boot disk data, virtual memory, monitor and speaker settings, system fonts, and other settings. In order to reset NVRAM and PRAM when booting a Mac, hold down the keys ⌥Option(Alt) + ⌘Cmd + P + R

If your Mac freezes during operation and is unresponsive, a force restart should help. To do this, press and hold the power button until the Mac screen goes dark, and then turn on the computer as usual.

Attention! With this shutdown, unsaved data in applications will most likely be lost.

2. Removing removable media

Eject (⏏) or F12

When a Mac with an optical drive and a disk inside crashes, the system may fail to boot from it and freeze. To eject media, press the ⏏ (Eject) or F12 button on your keyboard, or press and hold your mouse or trackpad button.

3. Selecting a boot disk

If your Mac has multiple drives installed and you can't boot the system from the default drive, you can call up the boot drive selection dialog and manually select the desired media. To do this, press and hold the ⌥ (Option) key immediately after turning on the computer.

4. Boot from CD or DVD

Similarly, you can tell your Mac to boot from a disc from its built-in or external optical drive. In this case, press and hold the C key on your keyboard.

5. Download from server

⌥N (Option + N)

When the local one has a NetBoot server on which the bootable system image is located, you can try to start the Mac using it. To do this, press and hold the key combination ⌥N (Option + N).

This boot method does not work on computers with an Apple T2 processor.

6. Run in external disk mode

If you don’t want to start your Mac, you can switch it to external drive mode and copy important files by connecting it to another computer via a FireWire, Thunderbolt or USB-C cable. To start in this mode, press and hold the T key while turning on.

7. Run in detailed logging mode

⌘V (Command + V)

By default, macOS does not display a detailed startup log, showing only a loading bar. If problems arise, you can enable a detailed log, which will help you understand at what stage of the download the error occurs. To do this, when turning on, press the combination ⌘V (Command + V).

8. Start in Safe Mode

When your Mac won't boot normally, you might want to try starting Safe Mode. It checks the disk and turns on only the basic components of the system, which allows you to determine which specific programs or services are causing errors. To boot into Safe Mode, press and hold the ⇧ (Shift) key.

9. Single-player mode

⌘S (Command + S)

This mode launches the system in an even more stripped-down version - only the command line is available in it. Nevertheless, with its help, specialists will be able to diagnose and correct errors if they exist. To launch in single-user mode, press the key combination ⌘S (Command + S).

10. Run diagnostics

macOS has built-in hardware diagnostic software that can help identify hardware problems. To run diagnostics, press and hold the D key.

11. Running network diagnostics

⌥D (Option + D)

If the boot disk is damaged, you will not be able to run the diagnostic test. In such cases, network diagnostics will help, allowing you to run the test via the Internet. To do this, press the combination ⌥D (Option + D)

12. Recovery mode

⌘R (Command + R)

When you boot into recovery mode, you can access Disk Utility, reinstall macOS, and restore data from a backup. To enter recovery mode, press and hold ⌘R (Command + R).

If your Mac has a firmware password, you will need to enter it.

13. Network recovery mode

⌥⌘R (Option + Command + R)

A mode similar to the previous one, which, if the Internet is available, allows you to reinstall macOS by downloading the system distribution directly from Apple servers. To use it, press ⌥⌘R (Option + Command + R).

14. Reset NVRAM or PRAM

⌥⌘PR (Option + Command + P + R)

If you're having problems with your display, speakers, cooling fans, or other Mac components, you can try resetting your NVRAM or PRAM to resolve them. To do this, press and hold the ⌥⌘PR (Option + Command + P + R) keys at startup.

If your Mac has a firmware password set, this method will not work.

15. Reset SMC

A more radical reset method is to return the system management controller (SMC) to default settings. It is used if the previous method did not help. Depending on your Mac model, resetting the SMC works differently.

On desktop computers You need to turn off your Mac, unplug the power cable and wait 15 seconds. Then reconnect the cable, wait five seconds and press the power button to turn on.

On laptops with a removable battery You need to turn off your Mac, remove the battery, and then press and hold the power button for five seconds. After this, you need to install the battery and press the button to turn it on.

On laptops with a non-removable battery You need to turn off the Mac and simultaneously press and hold the Shift + Command + Option buttons for ten seconds with the power button. After this, release all keys and press the power button to turn on.

On a MacBook Pro with Touch ID, the sensor button is also the power button.

If you need to boot from a secondary hard drive on your Mac, you can do so using several different tools. For most PC systems, you will need to press the F12 key or another function key, or perhaps the Escape or Delete keys, when the system boots to view the alternate boot drive selection menu. To do this, Apple computers use the Option key, however, there may be some restrictions.

Typically, you'll want to start or restart your Mac and simply hold down the Option key when the screen is black so that when you restart, you'll see a menu of boot options. However, if you are using a wireless keyboard, you may not see this menu and the system will boot into normal mode. This is because by holding down a key before the Mac initializes the Bluetooth keyboard, the key will not be recognized as pressed. Bluetooth controllers are initialized when the boot chimes sound; To open the boot menu, press and hold the Option key immediately after hearing the boot chimes, not before. The same approach applies to other boot modes: safe mode, single-user mode, verbose mode, etc.

When you have brought up the boot menu correctly, a gray screen will display the available boot volumes. For systems running OS X 10.7 or later, you should see the default Macintosh HD partition and Recovery HD drive. For systems running 10.6 or earlier, you should only see the master boot partition unless you have multiple actual operating systems installed.

At this point, you can attach external hard drives, flash drives, or optical drives that contain valid operating systems. And when they are recognized, they should appear among the current boot options.

You can then boot from the desired drive by selecting it with the mouse and pressing the arrow button, or using the arrow keys to navigate through the menu, pressing Enter to select the desired partition.

Any Mac that comes with an optical drive can boot from this drive by holding down the "C" key at startup. Although most recent Macs with support for this feature work with DVD drives, the "C" stands for CD, as it was implemented when Macs were released only with CD drives. For those who don't have a built-in optical drive, you can use an external USB DVD drive to insert the boot DVD and it will appear on the standard boot menu.

On a system running OS X 10.7, 10.8, or 10.9, you can boot directly from the recovery drive by holding down Command-R. Additionally, most systems released after 2010 support online recovery, which can be caused by holding down Option-Command-R. Keep in mind that this type of recovery will require an internet connection and the process will download approximately a 650MB image file from Apple.

Please note that selecting an alternative boot drive using this method will only affect the current session. Restarting the system will revert to the default boot disk. To change this, you will need to use the boot disk settings, which are available either in System Settings, Apple's Boot Camp drivers for Windows, or the recovery partition.

The Mac OS X operating system is one of the most stable systems. If you downloaded it, then weeks, or even months, may pass before the next reboot. But sometimes there are situations when you need to boot your computer in safe mode or external disk mode, or simply boot into another OS, for example, Windows, if of course you have it installed.

In this article we will talk about special boot modes for computers with Mac OS, as well as how to boot into them. To use these methods, you need to hold down the key combinations indicated in each mode as soon as you hear the sound of the operating system loading.

Selecting a boot disk

Boot from CD or DVD

Running from a NetBoot image (netboot)

Booting in Target Disk mode

Running Apple Hardware Test

This boot mode makes it possible to check your computer hardware for possible hardware problems. By pressing the D key during boot, you can run this diagnostic.

Booting in Safe Mode

Boot with display of service information (Verbose Mode)

Boot with Command Line Support (Single User)

It refused to boot. CMD+R doesn't help. What should I do?

The start of the working day did not foretell anything bad. A cup of coffee, a good mood, the Power key and the MacBook displays the following sad picture:

A worrying thought immediately flashed through my head about the safety of the data, the current version of the TimeMachine backup (which was not at hand) and the possible loss of information.

Attempt No. 1. Booting into recovery mode

Being an interested user and an avid Mac user, I immediately tried to start the MacBook in recovery mode by holding down the keys CMD+R. Instead of the usual disk utility, the system greeted me with a window with an attempt network recovery.

Having chosen my home network, I began to wait for further developments. After a few minutes, OS X's recovery progress was interrupted error -4403F.

Attempts to start the process again led to exactly the same result. Rebooting the router confirmed that everything was fine with the network connection.

Trying to carry out diagnostics, fix possible hard drive errors, or simply reinstall the system was now out of the question. Section with Recovery HD, in which the tools for restoration are stored, ordered to live long.

Attempt No. 2. Resetting PRAM and NVRAM

Mac computers were created by highly qualified engineers, so the correct organization of the entire system and the presence of “hidden hardware reserves” allows you to avoid a number of interruptions in its operation. One of these reserves is memory sections PRAM And NVRAM. It stores settings data that is not reset even after the computer is disconnected from power. To revive the fallen system, a decision was made reset PRAM and NVRAM settings.

1. Turn on the Mac.
2. After the white screen appears, quickly press the key combination CMD + Option + P + R.
3. Hold until the Mac reboots again and the Mac greets the sound.

PRAM and NVRAM reset completed.

Although they say that hope dies last, it, lifeless and barely alive, continued to lurk in my mind. Resetting PRAM and NVRAM did not affect the error when booting the system. The MacBook continued to test my nerves.

Attempt No. 3. Reset SMS

Having become accustomed to storing all the necessary data “in the cloud” or on removable media, the simplest solution to global problems has always been to reinstall the system “from scratch.” This case was special. I needed data stored in memory and I needed a working Mac today.

In the Mac environment there is something called system management controller SMC. The stability of the entire system depends on the reliability of its operation. Resetting SMC settings can cure a number of problems like:

— constantly high rotation speed of the cooler even at minimal load;

— freezes when the system goes into sleep mode;

— errors related to the operation of additional peripherals or external monitors, as well as correcting system boot problems.

To reset the SMC, follow these steps:

Laptops with built-in batteries

1. Turn off your MacBook and plug in the power adapter.
2. Press and hold the keys at the same time Shit + Control + Option + Power and hold until the MagSafe adapter indicator changes color.
3. Release all keys and press the key again Power.

Laptops with removable batteries (older models)

1. Turn off your MacBook and unplug the power adapter.
2. Remove the battery from the laptop.
3. Hold down the key Power And hold for at least 5 seconds.
4. Release Power, insert the battery and connect the power adapter. Turn on your laptop.

Desktops (iMac, Mac mini, Mac Pro)

1. Completely disconnect the computer from the mains power.
2. Wait at least 30 seconds.
3. Connect the power and wait another 5-10 seconds and then turn on the computer.

The above actions can become really effective and the system will start. In my case, a miracle did not happen.

Attempt No. 4. Recovery using a bootable USB flash drive

An attempt to revive the system using the above actions was unsuccessful. The only option left was to reinstall OS X using a bootable USB flash drive. For this step you will need:

another computer running the OS X operating system;
Flash drive with a size of at least 8 GB.

Preparing a flash drive

1. You will need to download the OS X Yosemite distribution from the Mac App Store.
2. To create a bootable USB flash drive, download the DiskMaker X utility (distributed for free). You will need it to deploy the distribution.
3. Format the flash drive using Disk Utility in Mac OS Extended (Journaled).

4. After the distribution has finished downloading, cancel the proposed installation and run the utility DiskMaker X.
5. Choose a system Yosemite (10.10). The utility will detect the distribution in the Applications folder. Click Use this copy(use this copy).

6. Select the drive installed in the USB port and agree to the warning about completely deleting all data present on the flash drive.

7. The process of mounting the distribution kit with OS X Yosemite to the drive will begin.

The copying process takes about 10-20 minutes and depends on the writing speed of the USB flash drive. During mounting, dialog boxes and folders may occasionally open on the screen. Never mind.

Once the OS X Yosemite image has successfully deployed, remove the drive.

System installation
1. Insert the flash drive into the USB port of the “problem Mac”, press the key Power and hold down the key Alt.
2. In the list of available download sections, select OS X Base System. Please note that there is no Recovery partition..

3. The Mac will boot into recovery mode. After selecting the main system language, the installation menu will open. In the top menu you will find a standard list of utilities.

Use disk utility and first try to check the access rights to the system partition and correct any errors. If after rebooting the system still refuses to boot, you will need to separate a partition of at least 20 GB in size in order to install a new system. You can find detailed instructions on how to partition a disk here.

From the same menu, you can either begin the process of installing the system on a newly created partition, or restore the system using a TimeMachine backup (see Working with TimeMachine).

CAREFULLY! Be careful when choosing the installation partition. The installation must be carried out not on top of the old partition, but on a newly created one.

After the installation is complete, you will have access to all the data located on the “damaged” partition with the old version of the system.

If you cannot create an additional disk partition

If for some reason you were unable to create an additional disk partition to install a new version of OS X, and saving the data remaining on the broken partition is still a priority, there is an option to install OS X using a previously created bootable USB flash drive on an external drive.

In Disk Utility, format the partition scheme to GUID Partition (Attention! All data on the external hard drive will be erased) and select formatting type Mac OS Extended (Journaled).

Installing the system on an external drive otherwise completely duplicates the method described above. By booting from an external hard drive, you will have access to the data remaining in the old system.