How to optimize storage for iCloud photos?

driverperception wrote: …I don't need a ton of storage, content with all photos being stored in the cloud.

This is not what iCloud does-- it is not what iCloud is designed for. iCloud is not a remote archive. If that's what you need, then you're trying to use a screwdriver for a hammer. And when it doesn't work, don't blame the screwdriver.

iCloud Photos is a synchronization service. When you engage iCloud Photos on a device, then the Library on that device is kept just the same as the iCloud Photos Library. So, for instance, if you take a picture with your iPhone, it is added to the iPhone's Photos Library, copied to iCloud Photos Library, and then copied to the Photos Library on each of the other devices that you have connected. If you delete a picture on your Mac, then that picture is deleted at iCloud and on all the other devices. This is what synchronize means.

If you are not wanting to use iCloud for synchronizing devices, iCloud may not be a good choice. And you can't think of iCloud Photos as a backup service, since it backs up mistakes, and there's no way to undo them. Whatever you do with Photos on your device-- it happens everywhere else.

You can use Optimize Storage on the Mac, on your iPhone, or on your iPad. You can set this on any device, independent of the others.  If you set a device to "Optimize Storage," then Photos may store only smaller images on the device and rely on iCloud to keep the full sized images. Having screen-sized images stored locally allows you to quickly scan through you pictures while saving lots of storage space. And, if Optimize is chosen, and you want to Edit a picture, Photos will reach out to iCloud to get a full sized image for you to work on. Your optimized Library may take up less than 20% of the space of a fully downloaded Library. But an optimized Library may be kept larger than that if the extra storage space is not needed.

Beware, though: backing up a Mac Photos Library with Optimize Storage only backs up smaller images. If you want to keep a true backup on an external disk for safe keeping, you need to have Download Originals checked. I use "Optimize" on my iPhone, but I would not "optimize" my Mac's Library.

How much free space do you have on your boot drive?

It's generally recommended to try to maintain a minimum of free space to 80 - 100 GB to optimize system and application performance.

You can do what many of us do and that is get an external drive (preferably an SSD) and copy your larger files, i.e. Photos, music and movie libraries to it. NOTE: always test the libraries on the EHD before deleting the original from the boot drive.

Since you didn't tell us about your computer or even the OS you're running, I'm guessing you don't actually want any advice-- but here goes: If you don't have enough free storage on your computer to accommodate an update, then you have way more problems than you're letting on. You should have at least 10% of your storage free, and I've seen problems arise with less than 15% free. You may need to offload some of your stuff to an external drive. And how are you handling backups-- do you have an APFS formatted drive that you can create a new volume on? Using "Optimize" on a Mac means that you can't back up optimized files. You shouldn't be relying on "Optimize" on a Mac.

I see Old Toad and I had the same idea.

Essentially, if the optimized size is more than space available, you'll have issues. You cannot limit space, only optimize. You may wish to consider keeping your library on an external drive Move your Photos library to save space on your Mac - Apple Support. You can then sync with iCloud and keep full-size versions locally while also backing up those versions using a second drive for Time Machine (or similar).

Old Toad wrote: … I believe that optimization doesn't kick in until there's only about 10% free space left.

Actually, my Photos Library that I synchronize is 140 GB on my Mac. My Optimized Library on my iPhone takes up about 5 GB. I have about 75GB free out of 128 GB on that iPhone.

I think that one of the reasons that my Optimized Library is so small is that I don't ever edit pictures on my phone, so Photos has no reason to download the originals..

driverperception wrote:

So as I understand it, if you have more photos in storage than you do space on your machine, nothing will stop iCloud from completely filling your local disk, crippling even OS updates.

Is there any way to limit how much local disk space Photos/iCloud has access to? If I archive some then they won't show in iCloud anymore, I'll only have access to them locally.

No. If there' not enough room on the drive Photos will not import the photo or download it from the iCloud library and you may be in a situation where you lose the photo.

That's why external drives were invented. You can get a 1 TB SSD like this setup:

for very little money. I have a 184 GB (55,000 photos and 900 videos) which opens in 2 seconds. I also have 6 other similar SSD connected to my Mac Mini.

You can get the SSDs in their own enclosure for more money.

Thanks, Richard. You just destroyed my belief system. 😧

Actually that was the tinking several systems ago. I don't use iCloud Photos so am only bringing up what I remember. (I'm surprised I can remember that far back).

Thanks for the feedback.

Old Toad wrote: Thanks, Richard. You just destroyed my belief system. 😧

When I actually stopped to look a while back, I was totally surprised at how little room the Library took up on my phone! I think I had seen 10-20% earlier, but it's been less than 4% for months, at least. I add pictures, delete a few, but the few edits I do are often on screenshots that I later delete. I should force a bunch of downloads and see what happens…

Your device will optimize storage over time provided that you have the optimization feature turned on.

I believe that optimization doesn't kick in until there's only about 10% free space left.