I’ve written a couple of articles about the Caching service in OS X Server 5 for El Capitan. As of OS X Server 5, the Caching service now caches local copies on the computer running the Caching service of iCloud content. This allows you to cache content once and then have it accessed by multiple devices faster. I’m torn on this option. On the one hand, I love the fact that I can cache things and on the other hand I find it frightening that a random user can cache things I might not want them to cache on behalf of another user. I know, I know, they’re encrypted with a device key. But when you have data on disk, it can always be decrypted. I almost feel like there should be a plist on machines that whitelists allowed caching servers. Maybe I should make a feature request on that.
Either way, as it stands now, I might be disabling this option in larger offices. To do so, I can write an AllowPersonalCaching key into the Config.plist file at /Library/Server/Caching/Config/. The most graceful way to do this is using the serveradmin command, followed by the settings verb and then caching:AllowPersonalCaching option, setting that equals no, as follows:
sudo serveradmin settings caching:AllowPersonalCaching = no
To turn it back on:
sudo serveradmin settings caching:AllowPersonalCaching = yes
This can also be done by dropping a Config.plist file into the correct location for new server installations. I’ll have an article out shortly on doing so, as you’d want to normalize a few options in the file before deploying en masse (e.g. if you have a large contingent of Caching servers to manage.