User level: Level 1 (4 points)Trying to clear up some storage space on my old MacBook Air (only 15 GB free). I've cleared out pictures, music, messages, email, etc. But, there is still 53 GB of memory being used for "not mounted". I'm pretty sure it's not the system files (39 GB?). Any ideas on how to free up this storage space (if possible)?
[Edited by Moderator]
Posted on Sep 28, 2026 2:03 PM
User level: Level 1 (4 points)Sep 29, 2026 12:09 PM in response to PJTmedia
I used Restart/Restore, Disk Utility to mount the unmounted drive, then erased it and ejected it. Now have 67 GB of free storage space. YEA!
User level: Level 9 (78,350 points)Sep 29, 2026 8:44 AM in response to PJTmedia
Storage space may not be immediately freed when you delete files or move them to external media because that "deleted" data may still reside in the APFS backup snapshots (from Time Machine or even some third party backup software). Usually these hidden & unmounted APFS snapshots will be automatically deleted in about 24-48 hours for Time Machine (third party backup software may behave different & may be more customizable).
It is also odd to see a second "Macintosh HD - Data" volume shown in your screenshot of Disk Utility. Perhaps that is the "unmounted" volume you are questioning. While I have seen seemingly duplicated items in Disk Utility.....I have not seen that happen in some years now. This second "Data" volume may contain some of your mysterious 53GB is residing.
User level: Level 8 (45,179 points)Sep 28, 2026 3:37 PM in response to PJTmedia
Re: MacBook Air Storage Space : " ... there is still 53 GB of memory being used for "not mounted". I'm pretty sure it's not the system files (39 GB?) ..."
Seems the "not mounted" memory may have something to do with an external storage drive, perhaps used for "Time Machine" back-ups ... or with a server? I could be wrong.
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Re: "Any ideas on how to free up this storage space (if possible)?"
May need to determine the "cause" in order to reveal or create the solution.
Originally posted at discussions.apple.com/thread/256366745