You can point the software update server data to whichever directory you like, as long as it's writable and can be read by OSX.

sudo serveradmin settings swupdate:updatesDocRoot = "/path/you/want/to/change/it/to"

Didn't work for me:

$ sudo serveradmin settings swupdate:updatesDocRoot = /Volumes/CacheServer Password:
swupdate:updatesDocRoot = "/Library/Server/Software Update/Data/"

Then when I open Server.app it has 'Macintosh HD' as the Server Location.

El Capitan, 10.11.1

@jlbrown yes, server will still live on macintosh HD but the software update server data will move to the directory you entered.

If you go to that directory, is the SUS data there? It should be. The rest of the server.app data will stay put.

You can check the location of your SUS data with the following command:

#!/bin/sh

sudo serveradmin fullstatus swupdate

@perrycj Do you know if the setting will stick after updating Server.app? I tried relocating the directory in a previous version of OS X Server ( I think it was under Mountain Lion or Yosemite), and whenever I would update Server.app it would revert back to the default location in the boot drive, which didn't have enough space (SSD).

I ended up creating a homebrewed Fusion Drive to give it enough space to store the downloads, and also my Adobe Update Server downloads.

I'm now trying your method to test (El Capitan 10.11.6, Server 5.2) relocating it to a RAID.

@perrycj The "serveradmin" command is not available in a fresh installation of OS X 10.11.6 + Server 5.2. I got a "command not found" error.

Since I had to reconfigure my storage, I did a clean install of the OS + Server.app. The command was there with the previous edition of Server.app, and after I had updated it to v. 5.2 to test your method before I did the clean install.

Software Update service is also not listed in Server.app sidebar even though its folder is present in /Library/Server with the base config plist. The service was listed when I did the initial test after updating the app before I did the clean installation.

Now trying to figure out what to do. I need this functionality.

@itupshot I'm running through that version this morning. I'll see what I can find.

@perrycj I figured out how to get Software Update service on the Server app sidebar again: from the menubar, View > Software Update.

That also seems to have activated the "serveradmin" command. I was then able to issue it first to check the existing "updateDocsRoot" location, and then change it to my RAID.

I then switched on the service, and it's been syncing with Apple the whole day. It'll probably take the rest of the night to finish.

I think I'm back in business.

@itupshot Glad to hear. Sorry I didn't get back to you sooner.

If you want to relocate all /Library/Server directory data to another drive in one fell swoop, select your server from the sidebar, then go to Settings tab, and click the "Change Location..." button under Service Data.

However, just be aware that, in the past, I've had some trouble when I've updated Server app after relocating the data. It would give me error messages about Profile Manager and Wiki server even though I never even switched on those services. I don't know if that is still true with the latest versions of Server app.

I only use Software Update, NetInstall, and Websites (for Adobe SUS) services on my macOS Server.