How to completely disable Ubiquity (iCloud syncing?) in Mavericks or above? I'm trying to debug a strange problem that is causing a Mac to unpredictably switch off instantly without warning. Looking at logs, the entries most recent before this last happened were to do with ubiquity, which I gather is to do with iCloud syncing (specifically, mmcs_engine_create, which I can't find any relevant info about), and TALagent, which I think might have been monitoring the live-ness of ubiquity.

The user doesn't use iCloud, so I'd like to completely disable it and related services to see if that stops the issue recurring. I've found guides on how to disable iCloud in Lion but the steps don't apply to Mavericks or above, and I'm struggling to find steps (it seems like Apple don't want to encourage users to disable iCloud, presumably because they hope to encourage its adoption).

Looking at answers to How to completely uninstall iCloud?, it suggests simply signing out of iCloud to "disable" it, but the user in question has never signed in to iCloud, so there's nothing to sign out of (yet the logs show Ubiquity still periodically runs).



(Mavericks answers would be ideal, but upgrading the OS might be an option, though I'd have to work around other compatibility issues, so Yosemite answers would be better than nothing)
There isn't an "ubiquity" you can simply disable IMO. I would exhaust other avenues of solving this problem. Random shutdowns are irritating, but the best thing I have is to train the user to:


Get sysdiagnose each time it happens. (or right after the reboot / when the problem is noticed)
Log the date and time of the error on a piece of paper


Establish that you will review the results every 10 instances. Once you have 10 to 30 reports, you'll know quite certainly if there is a pattern or if there isn't. Also, you'll have enough logs to report a bug to Apple or open a ticket to get AppleCare (or whomever you pay for support) to look at the details and get a fix/suggestion. Without data, you'll be chasing phantoms and get so desperate you'll want to cut out the guts (or hopefully just an unused appendix) of an OS in hopes it will help.