How to clear local time machine snapshots on macOS
If you ever find your Mac running out of precious space, it might actually be taken up by the local time machine snapshots. macOS is supposed to automatically purge it if you need the space. However in cases such as when installing a large game, the available space might hinder you from being able to install the game. Thus, you need to know how to manually clear local time machine snapshots in your Mac.
Here’s how you clear local time machine snapshots
TL;DR: The utility you need is one that’s called tmutil (Time Machine Utility). To clear local machine snapshots use the following command.
tmutil thinlocalsnapshots / 100000000000 4
If you want to read more to see what happens when you use tmutil to clear local time machine snapshots on your Mac, read on.
What happens when you use tmutil
First, let’s see how much space you have on your Mac first. You can view this using the info panel of your Macintosh HD or use the df -h command to review your current free space on your Mac. But there’s a catch. Let’s take a look at the two screenshots below.
Notice that the info panel shows the available space as 168.37 GB (127.76 GB purgeable) while the df -h shows only 39 GB of available space. When you do the math, 168.37 GB – 127.67 GB = 40.61 GB, which is about the same as reported by df.
Using tmutil -listlocalsnapshots / will list all the snapshots that’s currently on your Mac.
To clear the snapshots, use the following command.
tmutil thinlocalsnapshots / 100000000000 4
If you’re wondering what the parameters mean, / = root path, 100000000000 = to thin by 100GByte and 4 = highest priority. This command will take a while to run. Once done, use the listlocalsnapshots / option again to see if there are still any local snapshots not yet cleared. At this point, you should already have up to 100GB of local snapshots cleared. If you happen to have more than 100GB of local snapshots, you can run the command again to get the rest purged.
You can see the available space increasing overtime on the info panel as tmutil clears the local snapshots. Curiously, the purgeable space does not decrease.
Now, let’s see how much space we now have after clearing out the local snapshots.
df now shows we have 93 GB of available space! That’s 54GB more than when I started out. On Macintosh HD’s Info panel, 226.39 GB – 168.37 GB = 58.02GB of additional space. For my 512GB SSD MacBook, that’s a significant 10% of space regained!
As for the discrepancy between the two count, it seems this thread here explains how df only looks at the disk blocks and macOS Finder does a more thorough job to calculate the file sizes better.
Hope this helps you get back some of your precious disk space.
If this post has been useful, support me by buying me a latte or two 🙂
