How does Time Machine work with iCloud?

[Junichi]

Now with Sierra you can browse though history of the folder in iCloud Drive.
I just tested how it works.
I had a bunch of screen shots on the Desktop, which is in iCloud Dive, and I moved them to Trash.
And on the Desktop I entered Time Machine without connecting to my Time Machine disk. As I moved to "yesterday," the iCloud syncing indicator appeared, and after syncing, the screen shots appeared.
So what I understand from this is that iCloud Drive has information on what have been where at what point of time, and you can browse through them in Time Machine, without attaching an external hard drive.
I assume this works only in a short period of time after deleting the files since it permanently removes files from the cloud after certain days since the user delete them. Is that correct?
By the way, before iCloud Drive arrived, OS X had something some people called "mobile time machine" which is basically a backup system of Time Machine which allows you to recover deleted files without an external hard drive, and it was possible because your Mac would store deleted files in the hidden directory in the system. However from what I see here it may be that this is no longer the case because assuming the deleted files are on the "mobile time machine" directly, which is locally stored, the files should appear quickly without downloading anything from iCloud. Did Apple kill mobile time machine?
Also, assuming Time Machine now can utilize iCloud to browse and recover old files, is it possible to use Time Machine without having set up a Time Machine disk?
Another question is how Time Machine treats files on iCloud because if you have a file in iCloud Drive the file is not necessarily stored locally. It downloads as you try to open it. If the file is not local, does Time Machine still take a copy of it? If it does, it requires downloading every time Tame Machine takes a backup, which sounds daunting. However if it doesn't take a copy of files stored in the cloud, it almost questions the purpose of Time Machine: if iCloud fails, you can't recover your files.

 

[airlied]

I think what you said "mobile time machine" is a function that backup locally when the OS cant reach the time machine disks, if the disks back online the files stored locally will be moved to the time machine disks the the local file will be deleted. it is useful for few-days travel.
apple didnt remove this feature they just didnt show it in finder anymore i guess.

and if you store file in icloud it still has a local copy you dont have to download it everytime when backing up or opening time machine.

 

[Junichi]

and if you store file in icloud it still has a local copy you dont have to download it everytime when backing up or opening time machine.

I think I didn't make it clear. It depends on your iCloud setting, but Mac "optimize the storage" by removing files from the local drive, in which case you have to download it as you need. Another case where you have to download them as you need is when the file are synced from another device.

 

[airlied]

I think I didn't make it clear. It depends on your iCloud setting, but Mac "optimize the storage" by removing files from the local drive, in which case you have to download it as you need. Another case where you have to download them as you need is when the file are synced from another device.

Sorry still dont quite understand what you mean. do you mean if you use the optimize the storage settings to make some files storing only on cloud and wondering if your OS have to download it again when making a backup?

well as far as I know, this is a automatic process, which means the system only delete some local files that havn't been used for very long time, or something you just watched/listened recently. and these files are already in your local timemachine disks.

so if timemachine didnt see any changes of these files it wont download it again.

for example, you store file A.doc and B.doc in icloud, then icloud decides to move A to cloud then remove it from your local drive, this process means that you havnt access/change/modified file A for long time, and time machine has already back up A. so removing A does not effect what time machine does. time machine still "thinks" that this file is stored locally but since it is unchanged it will not make the new bakup.

If you need to make a change of A.doc you have to download it to your computer so time machine just backup this modified file.

As file B.doc, if like A.doc, you dont have a local copy, and modified it somewhere else, like on your iphone, the icloud will send a signal to your os saying the file has been modified (but will not download it if you dont access it), the time machine will realise it then download it and make a backup then delete it again from your local drive. So this process makes sure that every file being modified will be backed up by time machine, and no unnecessary downloading being made.

So "If the file is not local, does Time Machine still take a copy of it? If it does, it requires downloading every time Tame Machine takes a backup, which sounds daunting." yes, let me make a quick conclusion:

Time machine still make a copy of your "cloud only" files, it treats these file locally.

But time machine backs up only when you modified the file locally, or on other devices. So as long as you dont modify it, timemachine doesnt download it everytime.

If time machine backs up the file on the cloud, it will download the file then delete it, and it will not show you the process.

And sorry for my crappy English.

 

[Junichi]

I think I understood.
I almost forgot the fact that Time Machine doesn't take a copy if the file has not been modified. Downloading only if the file has been modified totally makes sense.
Thank you.
And your English is easy to understand.