How do you backup iPhone to an external hard drive?

Alicedkc wrote:

That is a bad, nonsensical system that will hopefully be fixed eventually. Why wouldn't they just make it so it could back up like a Time Machine backup? It's just weird.

That's iCloud. Which also provides off-site backup.

The local backup operations can be wired or wireless, and the backup involves a Mac or Windows system for storage.

The Mac or Windows system can also be involved with resetting and reloading and updating the iPhone or iPad, if a problem has arisen.

Do send your suggestion along to the folks at Apple.

99¢ is a bunch of extra money?

Yes, you should back up once to create the directory structure, which you can then move to the external drive, then create a symbolic link to it (you apparently already found instructions on how to do that).

How about moving some other stuff to the external drive temporarily to free up space to do the first backup? How much free space does your Mac have? Unless you have thousands of photos that you don’t sync to iCloud (which you apparently don’t, because you aren’t paying for iCloud storage currently) the backup shouldn’t be that large, because it doesn’t contain anything that can be redownloaded like music and apps.

Hmm, why do you pay $1.50 when I pay 99¢? Or are you in Canada?

Of the 400 GB, how much is music and how much is apps? Have you tried to back up to your computer and been told there wasn’t enough space? My phone has 150 GB used, but my backup is only 6 GB.

There's not a whole lot that can be done, here.

The iMac is under-configured for your current requirements and as you're well aware, and adding and booting from external storage and adding more external storage is about your only choice with this configuration.

Two or maybe three hard disks to be added, and preferably USB 3.1. SSD for performance, but that's more costly. Hard disk for capacity, (much) lower performance, and lower purchase price.

Or continuing to pay for iCloud storage and performing an iCloud backup, which'll be cheaper than overhauling the iMac hardware configuration.

Alicedkc wrote:

The iMac is completely fine for my computing requirements, it just doesn't have a big enough hard drive to back up my phone (and it shouldn't have to).

iPhone does not offer directly-attached local backup.

iPhone never has offered directly-attached local backup, either.

Options for backup are iCloud, or a local backup to a local Mac or Windows system.

Your Mac system lacks the necessary storage capacity for that backup—it's capacity-constrained for performing a local backup of your iPhone.

Which leaves you with adding more storage to the iMac, or paying for iCloud storage, or acquiring and using a Windows system.

Or not doing backups, of course.

Backing up to an external drive is not a feature supported by Apple. There is a workaround, but it’s kludgy and, as you realize, it requires having at least one backup first to create the SQLite database that holds the backup. MrHoffman’s idea of booting to an external drive has merit. But for what you want to do your iMac is undersized; there’s no way around that.

You need to consider backing up your photos some way in case of disaster. Dropbox, box.com, Google Photos are all good options. I think that Dropbox has a free account good for up to 1 TB, so you might check out that. And there is a Dropbox app that will sync photos automatically. Same with Google Photos; there’s a free version, but it doesn’t store full resolution. Or pay more to back up to iCloud. It will be less expensive than other options, as MrHoffman said.

Back up to iCloud.