How Time Machine Backups Work When using iCloud

Hi, this is Gary with MacMost.com. Let me explain what happens when you try to do a Time Machine backup and you're using iCloud Drive. 

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Now when you're using iCloud Drive the important thing to keep in mind is that there are two different modes. In System Preferences you'll find these in your Apple ID under  iCloud Drive and it's called Optimize Mac Storage. You can either have this Off or On. Now let's look at what happens when you have it Off. Let's dive down into iCloud Drive, into the Documents folder, let's say you have Desktop and Documents turned On and you've created a folder called Some Folder. In there you have five files. These are on your Mac. You look on your Mac in your Documents folder, Some Folder there's files A through E. Since these are in iCloud Drive these are also going to be on Apple's server. 100% of the files on your Mac in your Documents folder in iCloud Drive are going to be on your Mac and a 100% of them are also going to be on Apple's server. When you have Optimize Mac Storage turned Off everything is always going to be in both locations. Or it's easier to think of it as one location that you can access from different places. 

If you go to Backup with Time Machine, Time Machine is going to backup everything locally including anything you've got in your User Folder that's outside of iCloud Drive. Also anything that is in iCloud Drive. All these files are there locally on your Mac. All the data is there. Time Machine does its backup. It backs everything up. You have 100% backup. All your stuff if you are using Optimize Mac Storage turned Off. 

Now what if you turn it On. If you have Optimize Mac Storage turned On you may see something like this. Only some of your files are available on your Mac. It appears all the files are there. They are all going to be on your list. But some files, files you haven't accessed recently are going to be off-loaded. They are going to appear to be there but they are kind of like envelopes that are empty. There's nothing inside. The content of the files is missing. You could recognize these very easily because they have a little Cloud icon with an arrow pointing down in them. This icon allows you to click it and download those files so they are there. Or you can simply open up the file and, on demand, you're going to be able to download them from iCloud Drive before the file opens up. Note that 100% of your files are always on Apple servers. Optimize Mac Storage is for optimizing your local drive. The whole point of this feature is if you have a small drive locally but plenty of space on iCloud Drive. So if you have a terabyte of stuff you can have that all on Apple servers but maybe you only have a 512 GB hard drive so only some of the stuff, like in this case File A and C, are fully present with all the content. Files B, D, E are just hallow files. Nothing in them. The content is missing. 

In this case when Time Machine backs up you can only properly backup the files that are completed there. File A and C will be backed up. Files B, D, E can't be backed up. The contents are missing. 

So if you need a 100% local backup, all your files there all the time no exceptions, there are two things that you need to do. First is your Drive needs to be big enough to hold everything. If you have a terabyte of data you need to have a terabyte, probably 2 terabytes really, of drive space on your local Mac. Then step 2 is make sure Optimize Mac Storage is turned Off. This ensures that all your files are local as well as on the server at all times and Time Machine can back everything up. 

But, do you actually really need that? I argue that most people don't because even with Optimize Mac Storage turned On and not all your files local all the time you still are getting just about everything backed up, probably more than you even think. So let's look at the situation where you have Optimize Mac Storage turned On. Some of your files on your drive, only the files currently present, are backed up. So in this case Files A and C will be backed up. B,D,E will not. Or are they? Well here's the thing. They kind of still are. Let me look at two situations. One in which you create a completely new set of files. So you start a new project. You created a new folder for it called Some Folder. You've got your Time Machine backup going. You've got Optimize Mac Storage turned On. You create your first file. It's a new file. It's present on your Mac. It's going to get backed up. It may in the future get Off-loaded and not there. But that's way in the future. Right now Time Machine does its hourly backup and gets File A. File A is backed up. You can create four more files. They are all new files. They are all present on your Mac and they are all going to be backed up. It is going to be awhile before those are Off-loaded because you recently used these files. Optimize Mac Storage keeps around recently accessed files because they are the ones you most likely will need again. So everything here now is fine and Backed Up. 

Now let's say some time goes by. You accessed A and C pretty often. But it turns out B, D, and E you haven't accessed since you originally created them. There's no need to backup B, D, and E again anyway because it backed it up the first time. You haven't changed it since. Even if Time Machine had access to these files it still wouldn't back them up because it already has a backup of the file as it exists now. Time Machine backs up when there is change. It doesn't backup the same file over and over again if it hasn't been changed. So, in this case all five files are backed up and they are just fine even though now files B, D, and E haven't been accessed in awhile. They are not present locally. They have been optimized. You still have the backup because they were created and then backed up by Time Machine originally. You're are all good in this situation. Let's say file D is updated. It's downloaded. It has to be downloaded for you to update it. Once it is downloaded it has been recently accessed. It's going to hang around for awhile. Time Machine is going to back it up and Time Machine will get this new version of File D there. So it's all good. Everything is still backed up. 

From this point on anything you do, anytime you change a file, it's going to be present locally for Time Machine to back it up. So you don't have to have Optimize Mac Storage turned Off. Time Machine is going to be able to handle the situation just fine. You'll have the same backup you would have if Optimize Mac Storage was Off. 

Now let's look at a different situation. Let's look at a situation where some folder was created and you weren't using Time Machine. You've got Optimize Mac Storage On. So eventually, after awhile, files B, D, and E are off-loaded because you haven't accessed them in awhile. Files A and C are present because you have accessed them recently. Now, you start your Time Machine backup. Time Machine could only backup A and C. It can't access B, D, and E because they are not present locally. It can't back them up. Now you delete file D by accident. There's no way to recover it. Time Machine never actually saw the file local. It was optimized and off-loaded and only present on Apple server from the moment Time Machine started backing things up. Now that you have deleted it, it's gone. You can't get it back. Keep in mind by deleting it I mean it was dragged to the Trash and then Trash was emptied. It's a little hard to do as it should be. So hopefully this situation doesn't come up too often. If it does come up keep in mind it has to be with a file that you haven't accessed recently, since you actually started backing up with Time Machine. So this is a situation where by using Optimize Mac Storage and Time Machine you failed to backup a file and then you loose it. But how often does this actually happen? 

There are really three main times when you need your Time Machine backup. The first is a Catastrophe. Your Mac is stolen. It's broken. A meteor hits your house. Whatever. It's gone and you need to get all your files back. Another situation is you need to revert to an old version of a file. You are writing your autobiography and a few weeks ago you made some changes and now you want to revert back to before you made those changes. The third reason is that you had a file and you accidentally deleted it. A couple of weeks later you realize your mistake and now you want it back. 

So if you're using iCloud Drive Optimize Mac Storage and you've been backing up with Time Machine how can you recover in these situations. Well, in a catastrophe it turns out you're fine. You restore your local files with Time Machine. This gives you things back that say were in your Movies folder that weren't part of iCloud Drive. It also restores everything in iCloud Drive that Time Machine could get ahold of to backup. Then you sign into iCloud. Now you have access to everything that was on iCloud Drive including the file that Time Machine never got to see and never got to backup. You're back to everything restored. Just restoring from Time Machine, signing into iCloud and you're back. The fact that you used Optimize Mac Storage didn't hurt you at all. 

Now what about the situation where you revert to an old version of a file. Well chances are you don't need Time Machine at all to revert. Most modern apps, like Pages, Numbers, and Keynote or even things like Microsoft Word have a function where you can revert to a previous version of the file. So you can just revert to that previous version inside the app. No need to access your backup. But let's say it's a file that doesn't have that. It's a graphics file or something with an app that doesn't have a Revert To function. Well, if you change the file then that means the file had to be downloaded on your Mac, it had to be present there, which means the Time Machine got a chance to back it up, doing its regular hourly backups. Which means it is going to be there on Time Machine. You're covered. You can get this old version of the file back. 

How about if you delete a file? Well, if you delete a file and it's something you've accessed recently then it would have been present at some point on your local drive. Time Machine would have backed it up and now you can recover it using Time Machine. But there's that last situation where it's a file that doesn't appear to be important. You haven't accessed it since you started your Time Machine backup that you're using right now and it's just now present there in Time Machine. It's gone. This is the situation that's not covered. So you have to ask yourself is it worth it to get a Mac with a really big hard drive so you don't use Optimize and have everything present all the time. So you have a 100% backup to avoid this one situation or can you use the Optimize feature knowing that you're covered most of the time for most things that you use a backup for. 

Keep in mind that if you know that there's a file that's important to you, like for instance you are writing your autobiography but you haven't touched the file in a year and you've started a new Time Machine backup since then you could always go to that file and click the little cloud icon to download it. That will get it backed up. Or just open up any file and do anything with it and it will get backed up. You can even select a whole folder and say I want all this stuff. This is important tax information or whatever. Download that now and then it will be local for at least awhile and get backed up. So I hope this explains all the different aspects of using Time Machine backups along with the iCloud Drive Optimize Mac Storage option. As you can see you're pretty much covered even if you're using the Optimize Mac Storage function. But if you want to be absolutely sure that you're covered all the time it's just a matter of having a big enough hard drive and not using the Optimize feature. 

I hope you found this useful. Thanks for watching.