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I'm trying to use Time Machine to back up my Mac (Ventura 13.5) onto an external SSD ("BackupSSD"). Strangely, most of the backup folders appear to be on the internal hard drive in /Volumes/.timemachine instead of the external SSD's mountpoint /Volumes/BackupSSD 1. (I'm not talking about local snapshots, which are correctly in /Volumes/com.apple.TimeMachine.localsnapshots.) Can anyone explain what's going on? I want to make sure that if my internal drive dies, the external SSD alone can achieve a complete system restore.

When I view files through the Finder or Time Machine's UI, things look fine. The Time Machine menu says backups are going to the external SSD, "BackupSSD", on my Mac, niffler:

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And Finder tells me the backups are in the right place:

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But when I run tmutil listbackups, the backups appear to be on the internal drive in /Volumes/.timemachine:

% tmutil listbackups
/Volumes/.timemachine/060F4496-481F-4D98-8AB7-5CD03FEB24EC/2023-08-26-122149.backup/2023-08-26-122149.backup
/Volumes/.timemachine/060F4496-481F-4D98-8AB7-5CD03FEB24EC/2023-08-26-135115.backup/2023-08-26-135115.backup
/Volumes/.timemachine/060F4496-481F-4D98-8AB7-5CD03FEB24EC/2023-08-26-153333.backup/2023-08-26-153333.backup
/Volumes/.timemachine/060F4496-481F-4D98-8AB7-5CD03FEB24EC/2023-08-26-165131.backup/2023-08-26-165131.backup
/Volumes/.timemachine/060F4496-481F-4D98-8AB7-5CD03FEB24EC/2023-08-26-175142.backup/2023-08-26-175142.backup
/Volumes/.timemachine/060F4496-481F-4D98-8AB7-5CD03FEB24EC/2023-08-26-185217.backup/2023-08-26-185217.backup
/Volumes/.timemachine/060F4496-481F-4D98-8AB7-5CD03FEB24EC/2023-08-26-195206.backup/2023-08-26-195206.backup
/Volumes/.timemachine/060F4496-481F-4D98-8AB7-5CD03FEB24EC/2023-08-26-205201.backup/2023-08-26-205201.backup
/Volumes/.timemachine/060F4496-481F-4D98-8AB7-5CD03FEB24EC/2023-08-26-215213.backup/2023-08-26-215213.backup
/Volumes/.timemachine/060F4496-481F-4D98-8AB7-5CD03FEB24EC/2023-08-26-225216.backup/2023-08-26-225216.backup
/Volumes/.timemachine/060F4496-481F-4D98-8AB7-5CD03FEB24EC/2023-08-26-235219.backup/2023-08-26-235219.backup
/Volumes/.timemachine/060F4496-481F-4D98-8AB7-5CD03FEB24EC/2023-08-27-005241.backup/2023-08-27-005241.backup
/Volumes/.timemachine/060F4496-481F-4D98-8AB7-5CD03FEB24EC/2023-08-27-015245.backup/2023-08-27-015245.backup
/Volumes/.timemachine/060F4496-481F-4D98-8AB7-5CD03FEB24EC/2023-08-27-025314.backup/2023-08-27-025314.backup
/Volumes/.timemachine/060F4496-481F-4D98-8AB7-5CD03FEB24EC/2023-08-27-035324.backup/2023-08-27-035324.backup
/Volumes/.timemachine/060F4496-481F-4D98-8AB7-5CD03FEB24EC/2023-08-27-045328.backup/2023-08-27-045328.backup
/Volumes/.timemachine/060F4496-481F-4D98-8AB7-5CD03FEB24EC/2023-08-27-055341.backup/2023-08-27-055341.backup
/Volumes/.timemachine/060F4496-481F-4D98-8AB7-5CD03FEB24EC/2023-08-27-065345.backup/2023-08-27-065345.backup
/Volumes/.timemachine/060F4496-481F-4D98-8AB7-5CD03FEB24EC/2023-08-27-075346.backup/2023-08-27-075346.backup

If I look inside "/Volumes/BackupSSD 1", I see only a single backup directory:

$ ls -l /Volumes/BackupSSD\ 1 
total 24
drwxr-xr-x@ 5 root  wheel   160 Aug 27 07:53 2023-08-27-075346.previous/
-rw-r--r--@ 1 root  wheel  9433 Aug 27 07:53 backup_manifest.plist

where I see multiple directories in /Volumes/.timemachine:

$ ls -l /Volumes/.timemachine  
total 0
drwxr-xr-x  22 root  wheel  704 Aug 27 07:56 060F4496-481F-4D98-8AB7-5CD03FEB24EC/
$ ls -l /Volumes/.timemachine/060F4496-481F-4D98-8AB7-5CD03FEB24EC
drwxrwxr-x@ 4 root  wheel  128 Aug 26 12:21 2023-08-26-122149.backup/
drwxrwxr-x@ 5 root  wheel  160 Aug 26 13:51 2023-08-26-135115.backup/
drwxrwxr-x@ 5 root  wheel  160 Aug 26 15:33 2023-08-26-153333.backup/
drwxr-xr-x  2 root  wheel   64 Aug 26 15:54 2023-08-26-155223.backup/
drwxrwxr-x@ 5 root  wheel  160 Aug 26 16:51 2023-08-26-165131.backup/
drwxrwxr-x@ 5 root  wheel  160 Aug 26 17:51 2023-08-26-175142.backup/
drwxrwxr-x@ 5 root  wheel  160 Aug 26 18:52 2023-08-26-185217.backup/
drwxrwxr-x@ 5 root  wheel  160 Aug 26 19:52 2023-08-26-195206.backup/
drwxrwxr-x@ 5 root  wheel  160 Aug 26 20:52 2023-08-26-205201.backup/
drwxrwxr-x@ 5 root  wheel  160 Aug 26 21:52 2023-08-26-215213.backup/
drwxrwxr-x@ 5 root  wheel  160 Aug 26 22:52 2023-08-26-225216.backup/
drwxrwxr-x@ 5 root  wheel  160 Aug 26 23:52 2023-08-26-235219.backup/
drwxrwxr-x@ 5 root  wheel  160 Aug 27 00:52 2023-08-27-005241.backup/
drwxrwxr-x@ 5 root  wheel  160 Aug 27 01:52 2023-08-27-015245.backup/
drwxrwxr-x@ 5 root  wheel  160 Aug 27 02:53 2023-08-27-025314.backup/
drwxrwxr-x@ 5 root  wheel  160 Aug 27 03:53 2023-08-27-035324.backup/
drwxrwxr-x@ 5 root  wheel  160 Aug 27 04:53 2023-08-27-045328.backup/
drwxrwxr-x@ 5 root  wheel  160 Aug 27 05:53 2023-08-27-055341.backup/
drwxrwxr-x@ 5 root  wheel  160 Aug 27 06:53 2023-08-27-065345.backup/
drwxrwxr-x@ 5 root  wheel  160 Aug 27 07:53 2023-08-27-075346.backup/

Finally, if I cd into any backup directory /Volumes/.timemachine/* and run df, it's clear that it's on my internal hard drive, /System/Volumes/Data (see the rightmost column of output):

$ cd /Volumes/.timemachine/060F4496-481F-4D98-8AB7-5CD03FEB24EC
$ df .  
Filesystem    512-blocks       Used  Available Capacity iused       ifree %iused  Mounted on
/dev/disk3s5 15622171200 6841327280 8749769336    44% 2733912 43748846680    0%   /System/Volumes/Data

And here's some other info:

$ diskutil list
/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *8.0 TB     disk0
   1:             Apple_APFS_ISC Container disk1         524.3 MB   disk0s1
   2:                 Apple_APFS Container disk3         8.0 TB     disk0s2
   3:        Apple_APFS_Recovery Container disk2         5.4 GB     disk0s3

/dev/disk3 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +8.0 TB     disk3
                                 Physical Store disk0s2
   1:                APFS Volume niffler                 9.2 GB     disk3s1
   2:              APFS Snapshot com.apple.os.update-... 9.2 GB     disk3s1s1
   3:                APFS Volume Preboot                 5.1 GB     disk3s2
   4:                APFS Volume Recovery                801.8 MB   disk3s3
   5:                APFS Volume Data                    3.5 TB     disk3s5
   6:                APFS Volume VM                      20.5 KB    disk3s6

/dev/disk4 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *8.0 TB     disk4
   1:                        EFI EFI                     209.7 MB   disk4s1
   2:                 Apple_APFS Container disk5         8.0 TB     disk4s2

/dev/disk5 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +8.0 TB     disk5
                                 Physical Store disk4s2
   1:                APFS Volume BackupSSD               2.4 TB     disk5s1

$ diskutil info disk3 | grep -i "size\|location\|removable\|mounted"
   Mounted:                   Not applicable (no file system)
   Disk Size:                 8.0 TB (7998551654400 Bytes) (exactly 15622171200 512-Byte-Units)
   Device Block Size:         4096 Bytes
   Device Location:           Internal
   Removable Media:           Fixed

So the question is: where are my backups, really? If my Mac's internal drive dies, does the SSD really have everything it needs to do a full restore?

Thank you very much.

1 Answer 1

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So the question is: where are my backups, really? If my Mac's internal drive dies, does the SSD really have everything it needs to do a full restore?

The /Volumes folder is just a directory that contains the mountpoints of other volumes - network and removable drives. Technically speaking, it is a file on your local drive, but it's nothing more than a pass-through file so you can access your device.

The data, including your backup, is written to the physical drive itself and not stored locally.

To put this in Windows parlance, /Volumes/<name_of_mount_point> is like using D:, E:, and so on. Those letters just map to different devices (USB drive, network share, etc.). The E:, for example looks like it's part of your computer when in reality, it's somewhere else.

Try running the command mount. This will list all the mounts (in the /Volumes folder). It will show the device and its associated mountpoint. Below is a sampling of mine (excluding the system mounts) for illustration:

/dev/disk6s2 on /Volumes/My Passport for Mac 2 (hfs, local, nodev, nosuid, journaled)
/dev/disk5 on /Volumes/My Book VelociRaptor Duo (hfs, local, nodev, nosuid, journaled, noowners)
//[email protected]/Network%20Share on /Volumes/Network Share (smbfs, nodev, nosuid, quarantine, mounted by allan)
//[email protected]/home on /Volumes/home (smbfs, nodev, nosuid, mounted by allan)
//[email protected]/Backup_Media_USB-01 on /Volumes/Backup_Media_USB-01 (smbfs, nodev, nosuid, mounted by allan) 

In this, the first two are USB drives while the remaining three are network volumes. Each mount point is mapped to a folder within /Volumes so they can be accessed. When the mount is detached, the folder (for the mountpoint) will be destroyed but your data will be safe on the device you've written it to.

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  • Worth emphasising that what @DanB is seeing is perfectly normal (though somewhat confusing) and that the backups are on the external drive.
    – Gilby
    Commented Aug 28, 2023 at 0:35
  • Thanks @Gilby .. I added some clarifications.
    – Allan
    Commented Aug 28, 2023 at 1:28
  • Hmm, the mount command says that the drive mounted at /Volumes/.timemachine is my internal hard drive. Also if I cd anywhere in /Volumes/.timemachine/* and run "df .", I am still on /System/Volumes/Data. So these backup-related files still seem to live on my internal hard drive, not the external SSD. This is why I'm confused where the backups physically reside.
    – DanB
    Commented Aug 28, 2023 at 15:43
  • I've updated my question to show the output of "df /Volumes/.timemachine/060F4496-481F-4D98-8AB7-5CD03FEB24EC"
    – DanB
    Commented Aug 28, 2023 at 15:50
  • That just gives you the free space. Provide the output of diskutil list and diskutil info disk3 | grep -i "size\|location\|removable\|mounted"
    – Allan
    Commented Aug 28, 2023 at 15:57

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