Network-based Time Machine volumes are very useful. Having your backup drive in a remote location, one that’s physically isolated from your Mac, protects your backups in the event your Mac has a catastrophic failure. Another wonderful use for remote Time Machine volumes, such as Time Capsules or NAS (Network Attached Storage), is to allow multiple Macs to perform backups to a single central location. Of course, network-based Time Machine volumes have their own set of problems; one of the most common is the failure of the backup volume to mount on your Mac. This prevents Time Machine from accessing the remote volume, and usually results in the following error message:
Backup Volume Could Not Be Mounted
There are variations of this error message that you may come across, including:
Backup Disk Image Could Not Be Mounted
This error message and its variations are nicely descriptive, letting you know the problem is likely with the remote backup volume. Correcting the problem is usually simple; below I outline the most likely causes.
Network Connection
If you’re having problems with a Time Capsule or NAS, make sure they’re available on your network. Check your NAS manual for instructions on how to confirm that the NAS is present on your network. For Apple’s Time Capsule, do the following:
Password Incorrect
Time Capsule and most NAS products require a password to be provided before the network drive will mount on your Mac. If the password supplied automatically by Time Machine to your Time Capsule or NAS is incorrect, you will see the “Backup volume cannot be mounted” error message. This is actually the most common reason for seeing this error message. It usually means that the administrator of the Time Capsule or NAS changed the password and forgot to update all of the information for Time Machine users. If that’s the case, you can either return the Time Capsule or NAS password back to what it was when Time Machine last worked, or update the password on your Mac. To update the password on your Mac, follow these instructions:
Reselect Time Machine Backup
Change Keychain Password
You should now be able to successfully perform a Time Machine backup to your Time Capsule or NAS.
