I have an iMac that is running Mavericks with OS X Server. I have the Time Machine service set up on that machine, referring to a directory on an external drive that is connected via Firewire. Other Macs in the house use this as the Time Machine backup location.

All works fine as long as someone is logged into the server. However, if the server is rebooted, and nobody logs in, then all client machines' Time Machine backups fail with an "unable to connect to disk" error. As soon as anyone logs into the server, everything starts working again.

So, apparently the external drive is not mounted until somebody logs in. What is the easiest way to fix this?

I have found various pages around the net showing how to use automount and the /etc/auto_master configuration file to mount remote NFS and SMB shares automatically. Is this the way to do it, and if so, what do I put in /etc/auto_master for an external local drive?

Or do I need to create an /etc/fstab file and put something in it? (I find conflicting information about whether that is still used or has been deprecated.)

Or do I need to do something with launchd?

FWIW, here is the output of mount -v when the external drive "My Book" is mounted:

/dev/disk1s3 on /Volumes/My Book (hfs, local, journaled)

Update: After experimenting more, it seems that sometimes everything works as expected (that is, external disk gets mounted and clients can backup), and sometimes it doesn't. Maybe there is a race condition between when services start and when external-drive mounting completes?


I just upgraded one of my servers from Snow Leopard to Mavericks and I ran into a similar problem. I knew that I had fixed it before and the method still seems to work in Mavericks.

In /Library/Preferences/SystemConfiguration/ you need to add the file autodiskmount.plist with the following content:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">

It should go without saying, but you will need admin privileges to do this. I believe you will also need to reboot. Then, without logging in on your server, check if the other computers on your network can see the external drive.

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