

What is taking up all of my startup disk space? See how my version number in the “About This Mac” window matches the number in my Startup Disk section? Yep - That’s my startup disk.

Under macOS, you’ll find a version number.Click on the Apple Icon in the menu at the top-left of your screen.To make 100% sure that you know what drive is your startup disk, follow these steps: If you have more than one OS drive, your startup disk should be the one with the latest version of macOS running on it, but we’re going to make sure of that in the next step. It will also display “OS” and the version number of that OS. Here, again, you’ll find your hard disk(s) they’re probably named something like MainSSD or MainHD. If you have more than one, continue with the next step:Ĭlick on the Apple icon at the top left of your screen System Preferences > Startup Disk. If you only have one, skip the down to “What is taking up all of my startup disk space?” section. If there is more than one of these hard disk icons that show up on your desktop, it means you’ve got multiple hard disks on your Mac. These are disks on your Mac Catalina OS that you can “startup”, this is because they have operating systems on them.


So how do you fix your almost full startup disk? The same way you solve the problem of a packed fridge – you need to clear up space, of course. What to do when your disk is almost full? If your startup disk is full and you get a message of warning from your Mac, this is a serious indication that you need to free up storage immediately. A hard disk should never get beyond 85% capacity (especially a startup disk) as you will experience slowness and errors the further you get above that mark. It’s a lot like why is your fridge full? There is no more space! Your disk is almost full and this is very bad news for any drive. Why your disk is almost full on Catalina OS?
