OS X Server Essentials 10.10: Configuring Time Machine as a Network Service
Reference 17.1 Configuring Time Machine as a Network Service
Time Machine is a powerful backup and restore service available to users of OS X (OS X Yosemite, OS X Mavericks, OS X Mountain Lion, Mac OS X Lion, Mac OS X Snow Leopard, and Mac OS X Leopard); you can use the Time Machine service with OS X Server to provide a backup destination on your server to Time Machine users.
You can now configure a limit to the size of each client backup, but only a Mac running OS X Mavericks or newer will obey this limit. Apart from this limitation, Time Machine will by design eventually fill up the destination volume with backup files, so it’s a good idea to use a volume (or volumes) that you dedicate to Time Machine only.
It is also a good idea to use the exclusions in Time Machine on the computer being backed up to limit the amount of data being backed up to a manageable level. You might decide to back up only the user home folder and documents to save space.
You must turn on the File Sharing service for clients to use the Time Machine service. The destination you define in the Time Machine service will appear as a share point in the File Sharing list.
After you use the Server app to choose a destination for Time Machine backups, click the On switch to turn on the Time Machine service.
On the Time Machine destination, each client computer gets its own sparse disk image (a sparse disk image can grow in size), and there is an automatically configured access control list (ACL) to prevent anyone from accessing or deleting Time Machine files from the sparse disk image. The Backups pane shows a list of the backups done and their status.
If you later change the backup volume, users who use your server’s Time Machine service will automatically use the new volume. However, OS X Server does not automatically migrate existing backup files. The next time a client’s Mac runs a Time Machine backup, the user sees a warning that the identity of the backup disk has changed since the previous backup. After the user agrees to use the disk, OS X uses Time Machine to back up all the nonexcluded files, not just the files that have changed since the last time a successful Time Machine backup completed, so it may take a long time, depending on how much data is backed up.
Remember that you can use the Permissions edit functionality to configure user and group access to the Time Machine service.