{"id":35734,"date":"2022-04-29T16:20:49","date_gmt":"2022-04-29T20:20:49","guid":{"rendered":"https:\/\/mjtsai.com\/blog\/?p=35734"},"modified":"2022-04-29T16:41:53","modified_gmt":"2022-04-29T20:41:53","slug":"which-devices-should-you-boot-your-m1-mac-from","status":"publish","type":"post","link":"https:\/\/mjtsai.com\/blog\/2022\/04\/29\/which-devices-should-you-boot-your-m1-mac-from\/","title":{"rendered":"Which Devices Should You Boot Your M1 Mac From?"},"content":{"rendered":"

Howard Oakley<\/a>:<\/p>\n

\n

Before going any further, allow me to reiterate: unless you’ve got a compelling reason, only ever boot your M1 Mac from its internal SSD. That’s how it’s designed to work, and that’s how it works best, even when it’s not working properly.<\/p>\n

[…]<\/p>\n

The best reasons that I know for wanting to boot an M1 Mac from an external disk are when you need to be able to run several different versions of macOS, perhaps for testing purposes.<\/p>\n

[…]<\/p>\n

One last warning: don’t try cloning its internal SSD to an external disk ‘so that you can boot from that’. Sometimes you can get away with it, but the best way to install macOS on any bootable external disk is using its installer app, and not cloning.<\/p>\n

[…]<\/p>\n

If you want to use your M1 Mac when it’s booted from an external disk, aim for a Thunderbolt 3 device returning at least 1 GB\/s read and write speed, faster if possible.<\/p>\n<\/blockquote>\n

Around Mavericks or so, macOS started to perform much worse when booted from a spinning hard drive. (This was compared with earlier versions using the same hardware—obviously, adding an SSD made it perform better<\/em> than before.)<\/p>\n

Now, you can definitely tell when you’re using a slower SSD, even though it has at least double the throughput of a hard drive—and much better latency.<\/p>\n

Before, I think the difference was that macOS started trying to do more things at once, which played to the hard drive’s weaknesses. Now, I think we’re seeing a different effect, which is that SSDs have gotten a lot faster and<\/em> macOS is able to take advantage of that. (To a point—even with my new MacBook Pro’s fast SSD I can feel when the system is paging because Downcast or systemstats<\/a> is using 25 GB of RAM.)<\/p>\n\n

Previously:<\/p>\n