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What are the essential folders in Photos Library.photoslibrary to back up? 90% of the data is original photos, but the other 10% changes a lot. For an almost 2Tb Photos libray this amounts to a lot of storage if the entire library is considered to have changed as a result of changes in the 10%.

Frequent incremental backups of the entire library are also too time consuming and costly if one uses cloud backup services. Often the original image files do not change, and it's only sqlite or other database files that trigger an incremental backup.

I want to be sure I am backing up every original file, but I am less concerned about those I could regenerate (e.g. the face database) that also change frequently. I also want to retain the exif data and the file numbering from my camera. This last use to be captured in the file names in the masters/originals folder, but at some point Photos start using UUIDs for file names and now the UUID/numbering link is in a database. Since I want to retain those links I may need to include some database files in the backup.

Here is an example of a file that may be redundant and can be skipped:

Photos Library.photoslibrary/resources/renders/F/FB170E5B-AAAA-4B81-A0DE-CD59AF_1_201_a.jpeg

because it is scaled down version of this original:

Photos Library.photoslibrary/originals/F/FB170E5B-AAAA-4B81-A0DE-CD59AF.jpeg
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  • The data structure within Photos Library.photoslibrary is undocumented and Apple tends to change it sometimes, so relying on some heuristics to get the "important" parts is rather risky. Also, backup solutions usually work incrementally and on file level, so one changed file will not trigger a new backup of the whole library. So, not sure it's worth the hassle here.
    – nohillside
    Commented Mar 4 at 18:05
  • As nohillside says, a small change to one file does not cause the whole thing to be duplicated. Time Machine is very efficient. I would not rely on cloud services to transfer 2 Tb of data. Also remember that not all cloud services are actual versioned backups.
    – benwiggy
    Commented Mar 4 at 18:21
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    @benwiggy Just to clarify. This isn't for a TM backup. It is for a cloud backup to AWS S3 or Google Cloud. My concern is multiple backups over time of files that only change a bit. ./database/Photos.sqlite is 1 gigabyte and changes every time I import a file. With daily backups that can pile up since many S3-like services have retention times, the result being I pay for ~60 days of a file I just deleted, not to mention the network costs of an extra gig every time Photos.sqlite changes. @nohillside Totally agree. I should heed that.
    – John D.
    Commented Mar 5 at 21:08

1 Answer 1

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This answer is for macOS 14 Sonoma.

Time Machine only backs up 4 folders inside the Photos library:

  • originals
  • private
  • resources
  • scopes

These are sufficient for recovery as a working Photos library. Indexes for faces, content, etc. are rebuilt after (I think) you have opened the recovered library.

In particular, note that the database folder is not included in the backup.

That should be a starting point for you. You should test backup and recovery using your backup software.

Using Time Machine is the simplest and cheapest being included with macOS. But you might prefer Carbon Copy Cloner for local backup because you can configure backups in ways that TM does not provide.

Some comments:

I could expand this answer, if I knew:

  • what backup software you want to use,
  • backup storage (directly attached disk, NAS or cloud service), and
  • your intended recovery outcome (e.g. a working Photos library or just a collection of correctly named original photos).

Whilst this is not part of your question, I suggest that 2TB is a very large size for a Photos database. You might want to consider other photo management and edit software more suited to a large database - Lightroom is the obvious answer, but not the only one.

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  • I haven‘t used TM for years, but are you sure about TM backing up only parts of the library?
    – nohillside
    Commented Mar 5 at 7:31
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    @nohillside Yes. Based on a) my own TM backups and b) the com_apple_backup_excludeItem extended attribute on some of the folders and subfolders. I am running macOS 14.3.1. TM really is very good unless you need configuration of multiple backups.
    – Gilby
    Commented Mar 5 at 8:22
  • Thank you, Gilby. Space considerations are not a concern for local and local network backups, so I rely on a combination of Chronosync and Carbon Copy Cloner for those backups. Both excellent This is entirely for cloud-based backups. What I want to avoid there is files that undergo a lot of small, insignificant changes that bloat the backup with unnecessary versions I hear you about the large Photos library. I have lots of video and close to 20 years of photos though. Add to that digitized copies of photos dating back 80 years. I know of no better management tool. I edit photos much
    – John D.
    Commented Mar 5 at 21:03

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