Q In these rural parts Internet bandwidth is precious, and we would rather not download every update individually to each of our Macs. Am I right in thinking that OS X Server can now run its own local update service?

A OS X Server has long been able to provide a local service to Macs through Software Update. In Server 5, this has become quite complex because of the different approaches of Apple’s current online services.

Providing a local server for Apple’s OS X and related software updates is the task for which the Software Update service is designed. Valuable features include the ability to limit the server’s bandwidth in its link back to Apple’s servers, and to control the local network bandwidth used to transfer updates from the server to clients.

Whereas the old Software Update pane in System Preferences could be pointed at a local server instead of Apple’s, the App Store pane has no such facility. Instead you need to edit /Library/Preferences/com.apple.SoftwareUpdate.plist by adding a new property, CatalogURL, specifying the address of your local server.

Software Update server and its configuration is explained thoroughly here, and setting clients up to use it is detailed here.

The Caching service works with all content and apps provided by Apple’s Mac App and iTunes stores, which of course includes OS X updates, and is explained here. Macs and iOS devices connected to the local network will automatically find it when it is running; there is minimal configuration for the server, and none for the clients.

You can run Software Update and Caching services on the same server, but they cannot share files, and you must ensure that the server itself is kept up to date separately. Thus an update to OS X will need to be downloaded once by the server to self-update, once to the Caching Server, and once to the Software Update Server. However if you have severals Macs and iOS devices which regularly use your network, these services could result in worthwhile economy in bandwidth.

Updated from the original, which was first published in MacUser volume 29 issue 5, 2013.