Managing iCloud Drive with multiple macs
Sorry for all the detail here - complicated issues. After decades of using Macs and ignoring iCloud, I want to start using it as a sync/backup platform. However it seems to be difficult to find online answers to some simple questions about how it works. The more I read, I am realising that iCloud Drive seems to be really more of a syncing platform than a backup platform. I hope to use it for both.
If I have two Macs with desktop and documents synced in iCloud Drive, will iCloud merge everything or can I keep these separate? The general answer seems to be that everything is merged, but it's not clear. Machines will be using the same Apple ID. I want to be sure that I have continuous uninterrupted offline access to all my documents (but not necessarily photos, as they take up too much space) on my MacBook Pro (13-inch, M1, 2020), with its smallish 256GB SSD. However the norm appears to be for everything to be merged, and if you don’t have enough space on one device, iCloud chooses what to keep locally and what to keep in the cloud.
Is there a way to ensure that my documents will always remain on the Macbook SSD? Not so much data, about 15GB.
Possibly complicating this is that I would prefer to have access to the identical set of documents on both machines (the second one being a 2015 iMac 27", which I will replace with a new 27" when Apple releases the M1 version). But I don’t want to sync all the photos as this would exceed the SSD size, possibly triggering a situation where the system chooses to store my documents online only.
I realise that there may be a way to choose whether to sync Photos, independently of documents. However this is reliant on photos being in the Photos app. I have 300GB of photos that are not in Photos. Over time I could import them but I am wary of having them all stored this way without another system, and they are a huge mess and require a lot of culling and editing work before importing them. I need to use iCloud to back up all these pics, and I assume that the way to achieve this would be to simply move the Pictures folder into the Documents folder. However, doing this would create a huge Documents folder that would exceed the MacBook SSD capacity, creating the problem I am trying to avoid.
I see info online suggesting that I can force iCloud to store data locally by right clicking on a folder and selecting 'download now'. However it seems that if files are not used for a certain amount of time, icloud will remove them again. Nonetheless, would this approach resolve my problem? I could have one folder within Documents that contained all the pics, and download the other docs. Would this work if I was travelling for an extended period, say a couple of months, or is the system likely to default back to cloud storage within a timeframe like this?
Thanks for your patience ...
MacBook Pro 13″, macOS 12.2