Does iCloud sync to Mac when you're not logged in?

Hi folks!

I’d like to use an iMac as a “backup server” to sync iCloud data (full, not “optimized”) for various family members, thereby acting as a remote backup for them. Things like iCloud Photos, iCloud Drive, Contacts, etc. (I will also sync Dropbox to there, too, but that’s out of scope of this question…)

So, obviously I have to have accounts set up for them on the iMac and their Apple IDs and iCloud settings configured. The question is whether they need to be LOGGED IN for the sync to happen? The concern is that, after reboots, everyone is logged out, and I don’t want to find out months of data was not backed up because someone rebooted the iMac months ago without my knowledge.

A couple of people have asked, and not gotten adequate answers:

I could experiment; but there’s enough latency logging in and syncing, that I’d rather not trust trial and error. Curious if any of you have insight here.




Not to distract from your question (for which I’m also curious to hear the answer), but I’d also wonder if a user needs to be logged on as the current “GUI user” for lack of a better term, or if it’s good enough to use FUS to ensure that everybody initially longs on once (and they then don’t log out), and from then on all their iCloud stuff will always sync in the background, even if another user on that system in the meantime has become the foreground user.

Well, yes. Good question, and I was wondering that, too. Great minds lol. I’m expecting the answer to that will fall out of this discussion. Basically, if it can sync without being logged in, it can’t certainly sync without being the active “GUI” user…

I took a different approach with a Mac Mini that’s the backup destination for all our other Macs. I use CCC to copy data to the Mini. All the Macs have adequate storage so cloud data isn’t optimized.

I’m currently traveling and using my MacBook Air. Anything that changes is synced to iCloud, then synced back to my iMac at home which was left on. It is then backed up to the Mini and the Mini is backed up to BackBlaze.

Interesting setup.

Okay, so that works with your MBA. You mentioned “all our other Macs”. For me, that means Macs that are not in my home (kids at college). So CCC cannot access them (right?)

But the second (or maybe primary) difference with your set up is that for you, “All the Macs have adequate storage so cloud data isn’t optimized.” That simply not a workable solution for most of my family. With lots of media files, local MacBook storage is either prohibitively expensive or simply not large enough…

Yeah, the kids at college are a problem. I would try the fast user switching to see if it syncs when it’s not the currently active user. Should be easy enough to test with just two users. Set the users up and let them sync. Add a file to the non active users account, stop the internet connection, switch to that user and see if the new file synced.

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I don’t know about iCloud, but I know that Microsoft OneDrive volumes only sync when the OneDrive app is running - which is only when you’re logged in. And even then, it only syncs your files, not files belonging to any other users.

Now, iCloud is a part of macOS, so it may be doing things differently, but I wouldn’t assume so until someone can refer to an official statement or has actually tested it.


If you enable SSH (in the Sharing preference pane), you can test without logging in. Reboot the iMac. Then from another Mac, upload a largish file (100+ MB) to iCloud. Wait an hour leaving the iMac in its freshly rebooted, non-logged in state. Then ssh into the iMac from your other Mac, change to the iCloud directory on the command line, and see if your file is there. Even if logging in over ssh somehow triggers an iCloud sync, with 100+ MB, it shouldn’t have time to download in the <30s it takes to ssh in and list the iCloud directory.


For me, life is the process of hoping and praying someone else did the leg work and often finding out no one did so I have to do it myself LOL.

I may try this. Daughter just got home from college and hopefully has her (now unused) external drive so I can set it up for her local sync to this iMac.

But I’m not sure why I couldn’t just use glenthompson’s idea of just shutting off WiFi and then logging in to check…?

You absolutely could. My suggestion was in case you wanted to check whether iCloud syncing works straight after a reboot, before anyone has logged in. It also occurs to me that you could use ssh to disable WiFi and then log into the Mac as per normal to see if it’s synced. Apparently this command would do it (haven’t tried myself):

$ networksetup -setairportpower Wi-Fi off

(as per

:grin: I know what you mean!

So each of your people have their own appleid/iCloud account correct? Then when they sync to iCloud, all their data is on the cloud. They would need to all be logged into their own accounts on your Mac and signed into their iCloud accounts on there for them to sync with the Mac in the first place, as you said. If you leave them all logged in all the time and just switch users back to yours, it may keep their iCloud up to date while the Mac is running. Try it and see? Oh also, have power nap enabled in everyone’s Energy Saver setting.

Based on my experiments today, the answers are:



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