Time Machine backups have strange filenames

[soundslike]

I've recently migrated to a new macbook from my mid-2012 workhorse. I do Time Machine backups to a NAS on my home network, and in setting up the new macbook I chose for it not to pick up the existing backups as I want to keep using the older machine (and keep it backing up).

So anyway, I let the first backup run for the new machine, once the process was done I noticed that the backup file it generated had a weird name consisting of a random-ish string of characters, with no .sparsebundle extension: C10DP9~O

Showing package contents, it seemed to have the same structure inside as any other Time Machine backup.

As an experiment, I changed this file's name to something more familiar (the name I've given the machine in the sharing settings plus the .sparsebundle extension), and got Time Machine to 'Back Up Now'. It recognised the file, ran the backup, and promptly renamed it to another random-ish string: CT03S4~J

Does anyone know why this is happening? Do you think it's a problem? The backups seem to be working. I'm confused, and could use some advice. Thanks in advance!

 

[bernuli]

I've recently migrated to a new macbook from my mid-2012 workhorse. I do Time Machine backups to a NAS on my home network, and in setting up the new macbook I chose for it not to pick up the existing backups as I want to keep using the older machine (and keep it backing up).

So anyway, I let the first backup run for the new machine, once the process was done I noticed that the backup file it generated had a weird name consisting of a random-ish string of characters, with no .sparsebundle extension: C10DP9~O

Showing package contents, it seemed to have the same structure inside as any other Time Machine backup.

As an experiment, I changed this file's name to something more familiar (the name I've given the machine in the sharing settings plus the .sparsebundle extension), and got Time Machine to 'Back Up Now'. It recognised the file, ran the backup, and promptly renamed it to another random-ish string: CT03S4~J

Does anyone know why this is happening? Do you think it's a problem? The backups seem to be working. I'm confused, and could use some advice. Thanks in advance!

I would not mess with the file name of the image that Time Machine has created. Most likely the file name of the disk image is encoded.

 

[NoBoMac]

Wild guess, as not TM-ing to a NAS... guessing that along the lines of what @bernuli is talking about, "encoded".

Dumping the plist for Time Machine, lots of Apple UUIDs there. From a Terminal:

plutil -p /Library/Preferences/com.apple.TimeMachine.plist > ~/TMPlist.txt

When looking at the file, will see something like following. "DestinationUUIDs" is the TM volume that is currently mounted on my Mac. The name is "TimeMachine01" and that values shows nowhere in the plist. So, yeah, sorta encoding as mentioned.

  "AlwaysShowDeletedBackupsWarning" => 1
  "AutoBackup" => 1
  "BackupAlias" => {length = 304, bytes = 0x00000000 01300002 00010d54 696d654d ... 30312031 ffff0000 }
  "Destinations" => [
    0 => {
      "BackupAlias" => {length = 304, bytes = 0x00000000 01300002 00010d54 696d654d ... 30312031 ffff0000 }
      "BytesAvailable" => 3015528476672
      "BytesUsed" => 417808752640
      "ConsistencyScanDate" => 2022-07-30 20:18:15 +0000
      "DestinationID" => "1A00BC8E-B43C-404E-A2DD-E3141014EAD3"
      "DestinationUUIDs" => [
        0 => "F33388AC-C683-47AE-AA48-AE04989A87CD"
      ]   
      "FilesystemTypeName" => "apfs"
      "HealthCheckDecision" => 0
      "InheritanceDecision" => 0
      "LastKnownEncryptionState" => "Encrypted"
      "ReferenceLocalSnapshotDate" => 2022-07-30 20:16:45 +0000
      "RESULT" => 100