Jens Lodholm

Adapting Time Machine to Multi-User Environments

Losing data hurts, but before Apple added Time Machine to OS X Leopard, backing up itself could be painful. Now it’s simple. And this built-in utility has improved since its release in 2007.
Though aimed at consumers, Time Machine can be useful in professional environments as well. But to leverage it effectively, you must understand its strengths and limitations.

Causes of Data Loss

Understanding common reasons for losing data is key to protecting against them. Disk corruption and failure are a fact of computing, and they contribute to the loss of files.
Users make mistakes, too. Thankfully, Time Machine fills in gaps file versioning can’t cover.
How do you prepare against the day both a Mac and its backup storage go missing or become unusable? Plan ahead by storing backups in a safe location.


Time Machine can backup to a variety of destinations, so understand what your environment needs. Individual external drives for each Mac are simple and convenient, but they are vulnerable to damage or disappearance.
To overcome this danger, consider network-based storage for Time Machine. These central devices can be better secured against harm by hiding or locking them up.
Small environments may find Time Capsule ideal for its cost and capabilities. Its lack of central management may be acceptable for only a few Macs.
Larger environments can justify a dedicated Mac Server with attached storage. Apple’s Mac Server application includes a Time Machine service that enforces storage quotas on shared volumes. It even lists past backups so you can verify each client is protected.
Some NAS devices also support Time Machine. Know if a given device is compatible before you buy.
Since Time Machine allows multiple destinations, you can set up both a local drive and a network volume on each workstation.


Time Machine’s native hourly schedule is ideal for some, but a nuisance for others. Whether because of large files, hindered performance, or another challenge entirely, a 3rd-party scheduling tool overcomes it. I recommend Time Machine Editor, as it provides three distinct options. Adjust the schedule for each Mac’s needs.


By default, Time Machine backs up everything, making initial backups take a long time. But if you can easily restore the OS and applications (perhaps from a disk image), you can omit them from the backup. Simply click the Options… button in Time Machine Preferences, then click ‘+’ and select the System directory. When prompted to omit other files installed with OS X, click “Exclude All System Files”. Omit the Applications folder separately, if desired.
To streamline backup times and storage, eliminate other items according to the demands of your environment—non-essential users, music, and other data that can be easily replaced from another location. You may even omit very large files that you plan to backup manually. If you change your mind, you can easily remove exclusions later.


Time Machine makes it simple for users to restore their own files, but it’s a good idea to test recovery beforehand. This not only ensures that each user is comfortable locating and retrieving their data, but also that the correct data is actually there.


Time Machine is very good at what it does, but its shortcomings in some areas may require an additional solution for your environment.

  • Mac-Only - Other clients need another backup strategy.
  • Bootability - Macs cannot boot from Time Machine backups. Use Carbon Copy Cloner or Super Duper if needed.
  • Off-site Storage - Time Machine isn’t geared for remote backups in case of emergencies, but there are plenty of workarounds. If your organization connects to other sites by VPN, clients can backup to compatible storage on a remote network. If not, you can rotate external disks between any two locations, like office and home. Otherwise, explore Mac-friendly cloud-based backups, including iDrive, iBackup, CrashPlan, Backblaze, Mozy, Carbonite, and Apple’s own iCloud. Despite claims, these all require additional software or configuration outside of Time Machine.
  • Scheduling - Adjust Time Machine’s hourly default backup using Time Machine Editor.
  • Large Files - Time Machine doesn’t always adapt well to large files currently in use, such as with video and audio projects. If needed, alter your Time Machine schedule, back key files up manually, or craft another solution.
  • Interruptions - Whether a Mac crashes, loses power, or disconnects suddenly from the network, Time Machine responds poorly to sudden interruptions. Future backups may fail until a manual repair on the destination (see “Troubleshooting” below).
  • Encryption - Although Time Machine supports it, many drives are incompatible with Time Machine encryption. Know what your device allows before attempting.
  • Logging - Time Machine log entries are hard-to-find and sparse. This can make resolving advanced problems difficult.
  • Shared Destinations - Multiple Macs backing up to a common volume (such as a Time Capsule) may experience free space issues. The Time Machine service in Mac Server solves this with quotas.


  • First-Time Failure - If Time Machine can’t perform its initial backup, check the destination disk format. For network volumes, verify that the destination mounts.
  • Subsequent Failure - Confirm there is adequate free space on the destination. For shared volumes, force clients using the most storage to backup immediately in hopes of thinning their backup history. You may also remove backed-up items manually.
  • Latest Backup Not Current - If “Back Up Now” succeeds, verify Time Machine is on, unless using Time Machine Editor. In that case, check its schedule.
  • Stuck on “Preparing for Backup” - Interrupted backups leave an incomplete snapshot which may need to be manually deleted. Navigate to the backup disk, open the specific Mac’s disk image, and inspect the Backups.backupdb folder for an item ending in “.inprogress”. Unless a backup is currently underway, delete this file and try again.

With research and planning, you can successfully implement Time Machine in your environment. Keep refining your solution until it protects you against every foreseeable outcome. One day you may be glad you did.