WOW. HERE'S AN IDEA APPLE IMPLEMENT A PROPER BACKUP SOLUTION FOR ICLOUD PHOTOS
Sorry to shout but this is a MAJOR PET PEEVE and actually a downright SERIOUS risk to peoples data that Apple have neglected to implement an actual backup of your photo library. By back up I mean, a local, copy of my iphoto library. Uploading to 'another cloud provider IS NOT A BACKUP'
There are a major problems with current way they do things that stops this from being a reality. when your photo library gets 'quite large'.
let me explain:
For example:
If you have an iphone and macbook and maybe an ipad and you have a large library of photos, that could be taking up a SIGNIFICANT portion of your hard disk (500GB + ?) or something similar Some macs dont even have 500GB drives... anyway, you are using icloud photos, as I am, and I have 2TB of storage in the icloud.
You already have 'download original' ticked, so you have a local copy of your photos. It's on timemachine as well, and you can manually backup the photo.db library to anywhere on your network/backup device.
Now, in order to save expensive and not upgradable internal disk space, you decide to move your photos library to an external disk. Great. Only now you no longer have a portable laptop, you have to carry about a USB disk just to access your photos! or if you forget it, then you no longer have access to your photos. You also have to plug it in to actually use it. Also it's not clear what happens when you try to add or access the library if your drive is not plugged in.
Because mac does not let you have 2 libraries at once (you must CHOOSE the active/default library) you can't have for example a full library on external storage and a smaller optimised version of this library on the computer.
Additionally, all the photos that I take on my phone appear on my mac, full size as they get uploaded to icloud from the phone, and then downloaded to the mac.
If I tick optimised photo storage on the mac, then I solve my space issue, I also solve the above issue of being able to access my photos at all times (albeit lower res versions which is fine.... just like iphone well a laptop is a mobile device afterall) BUT, BUT , BUT I can no longer easily retreive and backup the full res version of images that originate from my iphone, or ipad as they go direct to cloud with no easy (read automatic no clicks, icloud to timemachine transfer) of full sized images.
So now I can't just back up my photos.db file as it doesn't have all the photos anymore.
Apple need to allow icloud to timemachine full res backups, or allow 2 simultaneous libraries that can be setup as 'full res copies' and 'optimised' so that when i plug in to the full res disk, it will update, just as it does now, without me having to pick one or the other by holding down a key when i start Iphoto. This makes no sense.
Addtionally for bonus points, if you have a family with ipads, and iphones, only such as kids how do they actually BACK UP their photos from their phones ?
The only way to solve this issue right now as far as I can see is to literally set laptops to have optimised libraries like a phone, then purchase a mac mini, plug in external drives, create a user account for each familiy member and set up the icloud photo sharing to download 'full copies' of images onto the eternal drives, which is now a few TB of photos data. This solves all problems above albeit an expensive way to do it. But I suppose that is the Apple(TM) Way.