macOS · System Info
Choose Which Disk Your Mac Boots From
Startup Disk lets you select which internal or external bootable volume your Mac uses when it powers on, useful if you have multiple macOS installations, a bootable backup, or a Windows partition via Boot Camp on an Intel Mac. Apple silicon Macs manage most of this through Startup Security Utility instead.
How to open Startup Disk
- Open System Settings → General → Startup Disk.
- Click the lock icon and authenticate if prompted.
- Select the volume you want to boot from by default.
- Click 'Restart' to boot into the selected disk immediately, or leave it set for next time.
What you should know
- Shows every bootable volume currently connected and available to start up from.
- Lets you set a default startup disk so the Mac boots into it automatically.
- On Intel Macs, holding Option at startup shows a temporary boot picker without changing the default.
- Includes access to restart directly into macOS Recovery from the same panel.
On Apple silicon Macs, changing the default startup volume and enabling external boot both require going through Startup Security Utility in Recovery Mode.
Why it matters
Choosing the wrong startup disk, or not knowing how to change it, can leave you unable to boot into the system you need — especially when troubleshooting, running a bootable backup, or dual-booting Windows on an Intel Mac. Knowing this setting also matters when installing macOS on a second internal or external volume for testing.
Best practices
- Reset the startup disk back to your main internal volume after testing an external boot drive.
- Label external bootable drives clearly so you don't accidentally boot into the wrong one.
- On Apple silicon Macs, use Startup Security Utility in Recovery to manage external boot permissions securely.
Common problems and fixes
- Mac boots into the wrong volume after connecting an external drive.
- Open Startup Disk in System Settings and confirm the correct default is selected, or hold Option at startup to manually choose the boot volume for that session only.
- An external bootable drive doesn't appear as an option.
- Confirm the drive actually contains a valid macOS installation, and on Apple silicon Macs, check that external booting is allowed in Startup Security Utility.
Tips and tricks
- Press and hold the power button on an Apple silicon Mac at startup to reach Startup Options, which includes Startup Disk selection and Recovery.
Frequently asked questions
How do I boot into a different disk just once, without changing my default?
On Intel Macs, hold Option at startup to bring up a temporary boot picker; on Apple silicon Macs, press and hold the power button at startup to reach Startup Options.
Can I select a network drive as my startup disk?
No, startup disks must be locally connected, bootable volumes — network drives aren't supported as startup options.
Related settings
- macOS RecoverymacOS Recovery is a built-in set of utilities for reinstalling macOS, restoring from a Time Machine backup, repairing a damaged disk, and resetting a forgotten password — all accessible without needing a working copy of macOS already running.
- Erase & Reset MacErase All Content and Settings lets you wipe your Mac back to factory defaults — useful for major troubleshooting, or before selling, trading in, or giving away your device.
- External StorageExternal Storage covers how macOS handles USB, Thunderbolt, and network-attached drives connected to your Mac — formatting them, choosing a file system, ejecting safely, and deciding which ones are eligible for Time Machine backups. Disk Utility is the main tool for managing these drives.
More System Info guides for macOS
- Date & TimeDate & Time settings keep your Mac's clock accurate by syncing automatically with a network time server, or let you set the date, time, and time zone manually when automatic detection isn't appropriate.
- About This MacAbout This Mac (accessible from the Apple menu) shows your Mac's model, chip or processor, memory, macOS version, and serial number at a glance, plus a detailed system report and storage breakdown for deeper troubleshooting.
- System ReportSystem Report (opened via the System Information app) provides a full technical inventory of your Mac — every connected device, installed application, network configuration, and hardware component — far beyond the summary shown in About This Mac. It's the tool Apple Support usually asks you to check when diagnosing hardware issues.
- Serial Number & CoverageThis is where you locate your Mac's serial number and check whether it's still covered by Apple's limited warranty or an AppleCare+ plan. You'll need the serial number for support calls, insurance claims, or verifying coverage before a repair.
- Sharing & Computer NameView and change the name your Mac uses on local networks and AirDrop, and manage which sharing services like File Sharing or Screen Sharing are enabled.
- Profiles (Device Management)See configuration profiles installed on your Mac by an employer, school, or manually, which can enforce settings like Wi-Fi configurations, restrictions, or MDM enrollment.