Nix Store Remnants on Time Machine

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1

I tried to install Nix a while ago on my Mac mini running Big Sur. I erased the hard drive and reinstalled Big Sur between then and now but I still have two volumes: “Nix Store” and “Nix Store 1” showing up on my Time Machine backups.

I can’t see these volumes using Disk Utility. Can someone help me purge these Nix leftovers from my hard drive?

2

Fair warning that I’m just spitballing since I’ve never used TM.

I’m unsure from this phrasing if the store volumes only appear in your TM backups, or if you’re also seeing them outside of the backup?

  • If they’re just in the backups, they’re presumably only in older backups? If so, is there a reason not to just let TM purge them naturally as it takes newer backups?
  • If you’re seeing them outside of the backups:
    • How do you see them?
    • Does diskutil list show them? If so, and they show up as APFS volumes, you should be able to remove them with diskutil apfs deleteVolume <identifier>

If you intend to keep using Nix, you may also want to exclude /nix/ from TM’s backups.

3

Thanks for the response. Here is this morning’s TM backup:

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I do not see these volumes using diskutil list:

% diskutil list
/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *500.3 GB   disk0
   1:                        EFI ⁨EFI⁩                     314.6 MB   disk0s1
   2:                 Apple_APFS ⁨Container disk1⁩         500.0 GB   disk0s2

/dev/disk1 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +500.0 GB   disk1
                                 Physical Store disk0s2
   1:                APFS Volume ⁨mac HD - Data⁩           34.8 GB    disk1s1
   2:                APFS Volume ⁨Preboot⁩                 346.2 MB   disk1s2
   3:                APFS Volume ⁨Recovery⁩                626.2 MB   disk1s3
   4:                APFS Volume ⁨VM⁩                      20.5 KB    disk1s4
   5:                APFS Volume ⁨mac HD⁩                  15.3 GB    disk1s5
   6:              APFS Snapshot ⁨com.apple.os.update-...⁩ 15.3 GB    disk1s5s1

/dev/disk2 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.0 TB     disk2
   1:                        EFI ⁨EFI⁩                     209.7 MB   disk2s1
   2:                  Apple_HFS ⁨Backups ⁩                499.9 GB   disk2s2
   3:                 Apple_APFS ⁨Container disk3⁩         499.8 GB   disk2s3

/dev/disk3 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +499.8 GB   disk3
                                 Physical Store disk2s3
   1:                APFS Volume ⁨Time Machine⁩            223.6 GB   disk3s2
4

Definitely sounds like it’s backup-only. I assume TM will purge those when the disk is full, and waiting for that to happen naturally seems like the safest course.

If that doesn’t sit well, you may be able to cut them out with the tmutil command. I haven’t used it for this, but the manpage for it has two sub-commands that sound like they might be usable for this?

delete path ...
   Delete one or more snapshots, machine directories, or backup stores.
   This verb can delete items from backups that were not made by, or are
   not claimed by, the current machine. Requires root privileges.

listbackups
   Print paths for all of this computer's completed snapshots.