External disk mode on Mac: what it is and how to set it up

Developers from Cupertino have provided different scenarios for using apple computers. Especially for this, the system has a number of settings that allow you to use “poppies” in unusual modes. In this material in the format “for dummies” we talk about external disk modein which cases it is used, features of use, etc.

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What is External Disk Mode?

If you have two Mac computers, you can set one of them as the head unit and the other as the main device. External Disk Mode, in fact, turning it into an analogue of a plug-in drive. High-performance, with a phenomenal data exchange rate, the keeper of invaluable information – in order not to clog the memory of the main gadget, the files are stored on the hard drives of auxiliary devices. You can activate this mode on any Mac computer with FireWire or Thunderbolt ports.

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Switching Mac to External Disk Mode in System Preferences

To do this, we need to change the boot disk format by selecting an alternative system boot option. Everything about everything will take a few clicks of the mouse:

one. Connect both Macs and devices with a FireWire or Thunderbolt cable.

2. Open the menu System settingsby clicking on the corresponding icon in Dockusing the Spotlight search service or by going to Apple Menu → System Preferences.

3. Click on the icon Boot disk.

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4. Click on the lock icon, enter the data administrator and click on the button Remove protection.

External disk mode on Mac: what it is and how to set it up

External disk mode on Mac: what it is and how to set it up

5. The desired button is located at the bottom right External Disk Mode – press it.

6. The system will ask you to confirm switching the boot format – agree and restart the computer using the appropriate button.

External disk mode on Mac: what it is and how to set it up

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How to Switch to External Disk Mode While Booting a Mac

Let’s say the computer is currently turned off – in this case, you can activate the desired mode quickly, without waiting for the desktop to fully load. We follow a short guide:

1. Press the power button and a moment after starting the device, hold down the key T.

2. Keep it pressed until you hear a beep.

3. Mac will automatically go to External Disk Mode. After the download is completed, the corresponding icon will appear on the screen of the main computer to which it is connected by cable.

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How to exit External Disk Mode on Mac

After finishing work, it is advisable to return the Mac to its previous state by deactivating the current mode. The procedure begins by disabling the established connection on the computer that served as the master device:

1. Connected as a drive, for macOS, our computer appears to be just another disk that needs to be ejected correctly. In the standard way – by clicking on the button “Extract» in the context menu.

2. Or alternatively, by dragging the icon of the connected Mac to the trash, which will be interpreted as a command to terminate the session.

3. It remains just to turn off the computer, which was previously in External disk modeby pressing the power button.

4. Disconnect the cable, restart the Mac – it will automatically switch to the usual mode of operation.

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What You Can Do in External Disk Mode

Exactly the same as with any external drive familiar to you, be it a flash drive or a removable hard drive. Having found the icon of the connected one on the desktop of the head computer, click on it and get access to the permanent memory of the Mac. Now you can drop any files there or extract the necessary objects by simply dragging them between folders. As long as both devices remain powered on and connected by a cable, a reliable, high-speed connection is formed between them. As a rule, it is better than via wireless Internet or a local area network.

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Any problems? Causes and solutions

The presence of peripherals connected via FireWire and Thunderbolt ports confuses the system – it cannot recognize another Mac that is in External disk mode. Therefore, before starting work, we physically disconnect everything superfluous by removing the cables from the connectors.

Key “T” or the entire keyboard may not work, which is a good idea to check in advance. It is better to give preference to accessories connected to the Mac directly, never through a Thunderbolt Display or a hub. And yes, make sure the wireless keyboard’s power supply isn’t running low.

In addition to the standard account password in macOS and authorization in the FileVault disk protection system, it is possible to block access to boot disk activation via FireWire with a secret key. This is used in cases where it is required to disable remote system boot, but for work External Disk Mode we need exactly the opposite – this password protection needs to be removed.

Check for the latest version of the OS, since in modifications of Mac OS X 10.3.9 and earlier there is no way to enable this mode for Macs with Intel chips on board.

Encryption of data in the home directory using FileVault creates serious interference in the work External Disk Mode. Simply put, you will have to forget about access to your files, or before you start working, you need to go to the settings and temporarily disable encryption. Do not forget to return everything to its previous state after the end of the communication session.

When using a laptop in External disk mode it must be connected to a power source. Firstly, we minimize the risk of disconnection due to low batteries, and secondly, there is no need to worry about the reaction of the portable device’s power saving system. She, according to the settings, can automatically turn off the computer’s drive to save energy, and usually this happens at the most inopportune moment.

It happens that during long downtime connected through External Disk Mode two Macs lose connection. This is due to the presence of bugs in the software for chips manufactured by Intel. The situation has long been brought under control, but a small risk still remains. The method of “healing” is standard – do not ignore the requests of proprietary software to install updates.

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Benefits of using External Disk Mode

High data transfer rates – that the Thunderbolt interface, that FireWire were developed for this very purpose. Copying files at a speed of several hundred megabytes per second is clearly more advantageous than using a USB cable or a Wi-Fi network. The optimal method for putting things in order in giant media libraries and archives of personal information.

The ability to install the OS on a second Mac – in case it does not have a display or optical drive, and you need to reinstall macOS right now. I don’t have the time or inclination to create a bootable USB drive or download an installer from the App Store, but you can copy the necessary files from your host computer by running the system setup directly in External disk mode.

Formatting the hard drive – since the connected computer is reflected in the system as just another partition, it is not difficult to use Disk Utility to correct it. Fast and painless formatting, partitioning, deleting information, etc.

Connected Mac Remote Troubleshooting – If your computer flatly refuses to boot, it’s a good idea to check the status of its files. Through the same extremely useful Disk Utility, after connecting External Disk Mode and thus gaining access to system folders. A very useful option in case of a critical failure, when it is impossible to start even in safe mode.

Rapid Data Migration – Although Apple has a policy of moving users to the “clouds”, the need and desire to transfer information in the old fashioned way still exists. When buying a new Mac, changing ownership of the computer, reorganizing the office equipment fleet, and similar cases, connecting External Disk Mode is one of the most efficient ways to move large amounts of data. Both with simple copying and using a tool called Migration Assistant.

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