So I've seen a lot of questions online recently from people who don't quite understand how
iCloud Drive works.
How does it sync your files between your Macs.
Where do the files go.
Where are they really.
Here's a presentation that explains it all.
We've got three different things here.
We've got somebody who has two Macs.
An iMac and a MacBook and there are currently no files on either one.
Then there's Apple's iCloud Server and they've set up their Mac to use iCloud Drive.
In fact to have Documents and Desktop stored on iCloud Drive.
You set this up in System Preferences.
Currently they have no files.
But let's say they create their first file.
Just a small file a text document.
We'll call it File A and they create it on their iMac.
What's going to happen pretty quickly and automatically is that file is going to be
uploaded to Apple's iCloud Server.
Now, of course, it depends how fast their connection is.
How stable their connection is.
But it should pretty quickly go up there and appear there.
Now you're probably not looking in your iCloud Server to see what's up there.
You can actually do that by going to iCloud.com and there's a file browser there.
But normally you wouldn't pay any attention to that.
You would just notice that maybe a few seconds or a minute to two later that file would appear
on your MacBook as well.
So you seem to have the same file on your iMac and your MacBook.
You could say that a copy of it has been put from one place to the other.
But these are treated as the same file.
So you make a change to it on your MacBook and you see the change on your iMac or vice
versa.
The change is going to happen in all three places as anything you do to these files is
going to sync the File A in your MacBook, your iMac, and Apple's iCloud Server.
You don't have to do anything to enable this.
It just happens if you have iCloud Drive turned on and you saved this file in iCloud Drive.
So let's say you create a bunch more files.
In this case B, C, D, and E and C is going to be a really big one.
A big video file or something like that.
This will then all sync to Apple's iCloud Server.
So all the files will be there first and then to your MacBook.
Again this may happen so fast you may not even notice it or if file C is really big
it may take a little while for it to happen.
But they'll sync across and will be treated on your MacBook and your iMac as the same
files.
Make changes to one and you'll see it on your other machine as well.
Delete one and you'll see it deleted on your other machine as well.
These files are all linked.
So file D is linked on all three locations.
Now there's an option called Optimize Mac Storage.
You can fine that in System Preferences in iCloud Settings.
It's under Options for iCloud Drive.
Now what this does is it allows your Macs to not have a copy of every single file.
So say, for instance, your iMac has a huge hard drive and your filling it up with files
over weeks and months.
Your MacBook, which has a smaller hard drive, is having trouble keeping up with this because
there's not as much room.
So your iMac has plenty of free space but your MacBook is getting pretty full.
What you can do is turn on Optimize Mac Storage.
Now what will happen is something like this.
That file C maybe is a large video file like I said and maybe you haven't accessed it in
a while.
Your MacBook notices that it's running short of space.
So it kind of gets rid of C. Notice it's still in the iCloud Server.
It's always going to be there.
It's still in iMac because there's plenty of hard drive space there.
But in your MacBook it appears to be there but it's not really there.
It's basically like a holofile.
It's an icon without a file behind it.
When you go to open it, it's going to then go out to the iCloud Service and download
that file so then you can open it.
So you don't have to do anything special to tell it to download that file.
You just open it like a normal file and you would be able to get access to file C. Now,
of course, if you're not connected to the internet, say you're taking a plane trip or
something like that, then yes it's a problem you wouldn't have access to file C. But if
you're connected via WiFi like normal you would have no problem.
You would just notice a delay as it went out and grabbed that file.
Now as soon as you went to access it, it actually puts it on your drive and now it's normal
just like before.
But later on if it notices that you're not using file C or one of the other files it
will then go and get rid of it again even though it will keep it there.
Now let's say file C you haven't used it for a long time on either Mac.
It may decide to actually get rid of it in both places if your have Optimize Mac Storage
turned on in both places.
So you can have Optimize Mac Storage turned Off on your iMac and it will never do this.
Every file will be there all the time.
Or you can opt to have it turned On and it will make decisions for your iMac and your
MacBook separately of which files it thinks it should have.
Over time it may do this for lots of files.
It's not just due to the file size, it's also due to the age.
So if you haven't accessed file B, even though it is pretty small, but you haven't accessed
it in a long time then it may actually kind of, you know, have that as a holo file there
not taking up any space and you can easily get it back by just going to open the file.
You may not even notice that it is downloading if you have a fast connection and it's a small
file.
If you go to download it then suddenly it appears there and now since you've used that
file recently it's probably going to stay there for a little while.
So you can easily get back to having all your files there by turning off the Optimize Mac
Storage if you want.
You can turn it On and Off at any time.
It doesn't effect what's on Apple's iCloud Server.
All your files are always going to be there.
It just effects what's stored locally.
You can't have any direct control over that.
So you can't tell a file, like, I don't need you so you can basically offload right now.
It's all decided automatically by Mac OS.
So using Optimize Mac Storage is the way to use iCloud to virtually get more hard drive
space on your Mac because only the files that you recently used, that it thinks you're going
to need, are there stored on your Mac.
Everything else is stored on the iCloud Server but will be automatically be downloaded as
you need them.
So turn that function on if you're running short on hard drive space.
But you can leave it off if you've got tons of hard drive space and would rather have
complete copies of every file stored in iCloud also saved to your hard drive.