The Case of the Broken Time Machine Backups

by danhon

We’re running Mac OS X Server 10.5 at work and I’d be lying if I said it had been a complete doddle to set up. Things that have been annoying so far:

  • the simple configuration option is really, really simple;
  • the advanced configuration option is really, really advanced;
  • there is no middle ground between “simple” and “advanced”;
  • periodically the DHCP server will just fall over.

There’s a pretty nifty (when it works) client configuration tool that ships with the 10.5 client called Directory Utility – if it works, it automagically discovers local servers and offers to set you up with them: you tell it your server account username and password, and your local username and password, it does some Kerberos magic to sync up the two accounts, binds you to the Open Directory, and then offers to configure client applications against any available server services, like iChat, iCal, Mail, VPN and Time Machine.

Brief digression: we’d run iChat if we could VPN, but we can’t, iCal Server is dead to us (it doesn’t allow you to invite off-domain attendees to meetings, sigh), Mail doesn’t make sense when we’re running Google Apps, VPN (router configuration issues). It’s Time Machine we’ve been having fun with lately, though.

At some point, Time Machine backups from OS X 10.5 clients to the server just Stopped Working instead of Just Working, and I’ve just figured out why, so I’m damn well making sure I’m writing it down so I can find it again. The answer was a bit obvious once I’d finally figured out where to look, and I feel a bit silly for failing to look for a few months now.

The Problem

Clients stop backing up via Time Machine to the Time Machine backup share point on the server.

New clients when being bound to an OS X Server through Directory Utility, fail when the Time Machine Backup configuration process attempts to complete, reporting a string like “an error occurred setting up backup” in the GUI.

Directory Utility will report to the console:

29/07/2008 17:05:52 [0x0-0x2c02c].com.apple.DirectoryUtility[287] 2008-07-29 17:05:52.517 UpgradeUser[316:10b] Attempting to mount volume Backups from server [servername] as user [username]

The Reason

Directory Utility appears to be hardcoded to look for an AFP share called “Backups”.

The Server Admin utility for OS X Server 10.5 will let you mark any share as a Time Machine Backup destination, but won’t tell you that for it to be configured by Directory Utility on a client, that the share must be exposed as “Backups”.

The Fix

Rename your Time Machine Backup desintation share name as “Backups”. Re-run Directory Utility to configure your clients.