OS X Server – Caching Service Part 1

By Richard Mallion and David Acland

So one of the advantages of Apple moving OS X Server to a single app is that they can deliver faster updates and new features.

Last week Apple delivered an update to OS X Server, bringing it up to version 2.2.

Along with the various bug fixes and tweaks they added a rather interesting new service called the Caching service.

So what does this caching service do?

The caching service helps speed up the download of software distributed through the Mac App Store. Which is aided by caching both software updates and purchased apps from the Mac App Store.

For years Apple have provided and still continues to provide, a service called Software Update which offers a similar service but there are some key differences:

  1. Software Update only caches updates, while the Caching service can cache both updates and Mac App Store purchases.
  2. Software Update initially downloads and caches all updates while the Caching service caches software based on client requests.
  3. Software Update provides client management options, such as the ability to restrict which updates the client can see while the Caching service has no client management.
  4. To use Software Update you have to reconfigure the OS X clients and point them to the specific server hosting the updates while with the caching server no configuration is required. The clients will automatically find the Caching server and use it.

It’s this last feature that is very useful. When you first enable the caching server, it registers its public IP and private IP with Apple.  If a client tries to download a software update or an app from the same public IP as the server, Apple “introduces” the client to the server automatically.

So as long as your clients share the same public IP address as the Caching Server they will use it.

You can even have multiple Caching Servers on the same network and the client will select the correct one.

For those of you that are using SUS as a local cache, you can finally switch this off, unless of course you still want the management functionality which in that case both services will run side by side. Please note these are independent services so each will download a set of updates. Also, if you configure your clients to use Software Update then this will take precedence and the client will not be able to use the caching service.

The setup of the Caching service is, as you would expect, very simple. Basically you just turn it on. You have a few options to select which drive stores the cache; how much disk space you want to reserve for the cache and an option to reset the cache.

All in all a very nice addition to OS X Server.

In part 2 we will look at some advanced features you can set by editing the services main configuration file, alternatively learn more about the Caching Service on the OS X Advanced Server  training course.