Select the volume that you want to start up from.Ĭlick Continue and the Mac restarts from that volume.No wonder I wasn't aware, my youngest Mac is a 2012 MBP.

When the Options icon appears, you will also see a list of volumes next to it that you can select. When you see your Mac has powered down, hold down the power button until you see a prompt that says “Loading startup options.” Here’s how you change the startup drive from recovery mode with an M1 or M2 Mac: This is a bit more complicated with an M-series Mac than an Intel one, where you could simply hold down the Option key while restarting and select a drive (unless you had turned on certain security settings, in which case you’d need to use recovery mode to disable them). You can also use recovery mode to change the startup disk. (Big Sur and later versions of macOS invisibly divide a macOS into a volume containing system files and a volume with your user data the data volume may not unmount correctly.) You might prefer to shut down at that point, unplug the external drive, start up again, and plug it in. You’ll have to unmount the external drive after the restart is complete, and some people have reported that macOS says one of its partitions remains in use. This should wipe out any conflicting data structures. Launch Disk Utility, select the SSD, click Erase, and follow prompts to create a single APFS container. To avoid setting up a volume that won’t work correctly, erase the drive before putting on data on it. But testing by many people makes it clear you can’t just change the formatting on an existing drive: invisible partitions used for purposes related to booting from an Intel drive from a previous macOS installation on the drive cause issues. To use macOS 11 Big Sur (the first M-series compatible version of macOS) all the way through macOS 13 Ventura (and for future releases), the drive has to be formatted as APFS. (It is possible to use an HDD as an external M-series startup drive, but the performance will be so poor, even with a 7200 rpm hard drive, you’ll wish you hadn’t.) Erase and format as APFS

Consult this Mac 911 column for more details on the two interfaces and their throughput.

You need Thunderbolt 3 or 4 to gain a benefit from the newer NVMe/PCIe interface, which can be several times faster than a SATA SSD, and about two to three times as expensive. Most inexpensive external drives use a flavor of USB 3 to connect over USB-C and rely on the slower SATA format, which coupled with an SSD is about 10 times faster than a hard disk drive. Fortunately, macOS appears to have matured, and you can use either USB 3.1 or 3.2 or Thunderbolt 3 or 4. With the first versions of macOS that worked on early M-series models, many people found they had to use a native Thunderbolt 3 or 4 drive.

Booting imac from usb