I manage a Macos Monterey computer, and I'm using a cloud backup service for it, including its Photos.library. When files are deleted from the computer, the backup service moves the corresponding backup-file to the cloud trashbin.

Today, the backup service notified me that "a large number of files have been deleted from your backup", and offered me to recover them from the cloud trashbin.

Upon inspecting the trashbin, I see that 3891 files and 4329 folders have been deleted. Screen shot of backup service

They were all originally in ~/Pictures/Pictures library.photoslibrary/resources/cpl/cloudsync.noindex/storage/filecache/.....

  • About half of them are actual .jpeg files, in the original file size.
  • Most of the other files have a UUID filename and no file extension.
  • There are also a bunch of folders named PrimarySync-[random string]

I did some random samples of the .jpeg - they could still be found in the actual Photos app on the Mac, so I'm pretty sure nothing important has been deleted here.

My questions are:

  • What are the files within ~/Pictures/Pictures library.photoslibrary/resources/cpl/cloudsync.noindex
  • Can I be reasonably sure that nothing important is being deleted?
  • The files have almost certainly not been deleted on purpose. Why has the OS (and/or Photos.app) deleted them?

1 Answer 1


As a general comment on Photos and its libraries, we are not supposed, by Apple, to need to know about the internal structure and how it is managed. Nevertheless:

  • What are the files within ~/Pictures/Pictures library.photoslibrary/resources/cpl/cloudsync.noindex?

From the folder names, I am pretty sure these are related to syncing (either potential or actual) with iCloud.

  • Can I be reasonably sure that nothing important is being deleted?

Time Machine does not attempt to backup anything inside ~/Pictures/Pictures library.photoslibrary/resources/cpl, so I am confident you have not lost anything.

  • The files have almost certainly not been deleted on purpose. Why has the OS (and/or Photos.app) deleted them?

Ah, the mysteries of what we are not supposed to touch! At a guess, Photos has decided it does not need them for syncing with iCloud. That is temporary storage not longer needed. They might come back again.

The most essential folder within the Photos library is originals.

Having created an answer to your questions, I have a few comments to make about what you are doing.

  • Jottacloud describes itself as a backup, but in reality it is a synchronisation from your Mac to its cloud. In other words, what is stored in Jottacloud is intended to be identical to what is on your Mac. If, as you have discovered, something is deleted (or corrupted) that will be duplicated to Jottacloud.
  • A true backup keeps old files in case you need to recover them in the future. Similarly it keeps old versions of files which have changed. Examples are Backblaze which keeps old files for a limited time and Arq Backup which keeps old and outdated files as long as you want (and can pay for storage).
  • With a backup service, it is best practice to configure it use the same exceptions as Time Machine.
  • Whilst you are keeping current copies of your data in Jottacloud, you should also have a local backup. Time Machine to an external disk is the most straight forward way of doing this.
  • "Time Machine does not attempt to backup anything inside ..." that's really useful information. Thanks! Nov 7, 2022 at 13:00
  • I agree with you that Jottacloud is more of a cloud sync utility than a backup utility, but it does keep "deleted" files for 30 days, allowing me to recover them. Jottacloud also has the advantage of storing data in its own cloud in my country, which takes some privacy worries away. Nov 7, 2022 at 13:03
  • There are good reasons to use Jottacloud - my worry was that you might get a nasty surprise in the event of some disaster to your Mac. Please test your recovery process. Mac 'packages' like Photo and Music libraries are particularly tricky to restore in their entirety from either sync or backup services unless the service is 'Mac' aware rather than just keeping copies of files. Most important, make sure you can recovery all your photo originals.
    – Gilby
    Nov 7, 2022 at 21:33

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