Make external drives mount at Mac boot
Sometimes it is nice to make external drives mount at boot (and not only when a user logs in) on your mac. This e.g., useful if you have an external USB drive on your Mac Mini that you want to use for Time Machine Backup from other macs without somebody are necessarily logged in on the Mac Mini.
To make drives mount at boot, you simply run the following command:
sudo defaults write /Library/Preferences/SystemConfiguration/autodiskmount AutomountDisksWithoutUserLogin -bool true
For more information, see here.
Bonus information:
In some cases it is nice to have the external drive mount somewhere else than in /Volumes, see here for more details on how to do this. Basically you create an /etc/fstab file (using the command vifs) containing:
#
# Warning - this file should only be modified with vifs(8)
#
# Failure to do so is unsupported and may be destructive.
#
UUID=10B21892-C061-3B8F-84BD-DE8BC1B0C6BC /Storage/Backup hfs rw
UUID=E7C208DA-63E9-39EC-B7B9-E63C6A2B92E4 /Storage/Extra hfs rw
where the UUIDs are taken from diskutil info.