If you use Time Machine to back up your Mac to an external hard drive, you might assume that your backups only happen when that specific drive is physically plugged in. However, modern versions of macOS utilise a feature called “Local Snapshots.” Even when your backup drive is disconnected, your Mac secretly records every change you make and stores these backups directly on your internal SSD, waiting to transfer them later.
While this provides an excellent safety net for recovering accidentally deleted files on the go, it can rapidly consume massive amounts of your internal storage space. If you are using a MacBook with a small 256GB SSD, these invisible snapshots can quickly fill your drive, leading to “Disk Almost Full” warnings even when you hardly have any large files. If you are struggling for space, you can disable this background caching completely.
Disabling Local Snapshots via Terminal
Because Apple considers this a core system safety feature, there is no graphical toggle switch in System Settings. You must disable it using the Terminal.
- Open the Terminal application (you can find it by pressing Cmd + Space and typing “Terminal”).
- Type the following command exactly as written and press Enter:
sudo tmutil disablelocal - The terminal will prompt you for your administrator password. Type it in (the characters will not appear on screen as you type) and press Enter.
Once you execute this command, macOS will immediately stop creating new local snapshots. More importantly, it will automatically begin deleting all the existing hidden snapshots on your internal drive, potentially freeing up gigabytes of storage space within a few minutes.
Re-enabling Local Snapshots
If you later upgrade your Mac’s storage or decide you want the safety net back, reversing the process is just as easy.
- Open the Terminal application again.
- Type the following command and press Enter:
sudo tmutil enablelocal - Enter your administrator password to confirm.
Time Machine will instantly resume hoarding background backups on your internal drive.