I recently signed up for iCloud photo, which has been working pretty well apart from one thing I'm struggling with. My photo library is about 200GB and was previously in Aperture. It migrated into Photos just fine and is stored on a second local disk at /Volumes/Media/Pictures/Photos Library.photoslibrary The initial upload to iCould went fine. However since then my boot volume keeps running out of space, on investigation it's being used by ~/Library/Caches/com.apple.photos.cloud, which rapidly chews through the 20GB that's available until there's none left. I have tried deleting it and also the CloudKitMetadata directories but it just comes back. If I symlink com.apple.photos.cloud to some spare space on another volume Finder starts to take ages to show folders and I get exceptions in the system log. Code: May 25 17:17:56 odin.local cloudd: paths don't match: /Users/USER/Library/Caches/*/Assets != /Volumes/*/Assets So that doesn't seem to be a solution. I have 'download originals to the Mac checked' because I want it to transfer originals from all my devices to this Mac, and I assumed this would make them show up in the main 'Photos Library' where there is ample space to keep this stuff. I can then backup this library to keep a local backup of all my photos. However it seems something else is happening and as such I'm not sure what 'download originals to this Mac' actually means. If I choose 'optimize space' is there a chance it would delete photos from the Photos Library? Because I want to ensure I always have my originals on this machine. Any ideas? At worst if I could get away with redirecting com.apple.photos.cloud to a different drive that would be a start.