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APFS Time Machine local snapshot consuming 95 GB purgeable space on M3 MacBook Air

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Home › Forums › MacBook, iMac & macOS Lab › APFS Time Machine local snapshot consuming 95 GB purgeable space on M3 MacBook Air

Viewing 4 posts - 1 through 4 (of 4 total)
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  • November 11, 2026 at 6:12 pm #44
    Alex Tanner
    Participant

    Disk Utility shows 95 GB marked purgeable after a failed Xcode install, and macOS installer refuses an update claiming insufficient free space. Does tmutil listlocalsnapshots / safely let me thin only stale local snapshots?

    November 11, 2026 at 6:12 pm #45
    Rachel Kim
    Participant

    The 95 GB “purgeable” figure represents APFS snapshot metadata pinned by the failed Xcode install (massive ~/Library/Developer/Xcode deltas), not active file data; WindowServer CPU spikes often correlate with mds/mdworker aggressively indexing these snapshot deltas during login item initialization. tmutil listlocalsnapshots / is read-only and safe—it merely enumerates the snapshot UUIDs. To reclaim space, you must explicitly thin them: sudo tmutil thinlocalsnapshots / 999999999999 4 forces urgent reclamation (priority 4), which diskspaced honors asynchronously. Verify physical block release with df -h / post-execution; a reboot clears any stalled kernel purgeable reservations on Apple Silicon unified memory architectures.

    MacBook Pro 14″ M4 (32GB) | iPhone 15
    Vancouver, BC | "Read crash logs bottom-up from the faulting thread."
    November 11, 2026 at 6:12 pm #46
    Claire Bennett
    Participant

    The macOS installer’s “insufficient space” error is a false-positive logic check (analogous to Error 4013/9 generic comms failures) where osinstallersetupd queries physical free blocks (statfs) ignoring the APFS purgeable reserve; Finder’s syncdefaultsd/FileProvider sync state often lags behind diskspaced reclamation, showing stale capacity. tmutil deletelocalsnapshots targeting the specific failed-install timestamp is surgical and safe—APFS copy-on-write ensures zero data loss for the live volume. If the installer still blocks, trigger immediate reclamation via sudo diskutil apfs resizeContainer disk0s2 0 (grow to fit) which forces the reclaimer; ensure MagSafe/PD handshake is stable (no pmset -g log power assertions) as power loss during snapshot teardown corrupts the APFS superblock.

    MacBook Pro 16″ M2 Max | iPhone 16 Plus
    London, UK | "Swap the USB-C cable before blaming the logic board."
    November 11, 2026 at 6:12 pm #47
    Nina Patel
    Participant

    Snapshot immutability is enforced by SIP/AMFI (per Security Bulletin HT212689)—you cannot rm -rf .MobileBackups; only tmutil verbs bypass the com.apple.rootless seal. iCloud Drive “Optimize Mac Storage” (Family Sharing sync) purges *file content* but retains *snapshot inode references*, inflating purgeable accounting until the snapshot TTL expires or manual thinning runs. tmutil listlocalsnapshots / confirms the stale Xcode snapshot exists; sudo tmutil deletelocalsnapshots is the supported remediation. Post-deletion, run sudo xattr -rc / to clear any residual quarantine/privacy extended attributes (Safari WebKit sandbox leftovers) that prevent diskspaced from marking blocks truly free.

    MacBook Pro 14″ M1 Pro (32GB) | iPhone 15 Plus
    Melbourne, AU | "Verify Rapid Security Response builds right in Settings > About."
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