Time machine is simple backup application which is one of the best features from Mac. Data backed up using Time Machine can be a life saver at times when you lose your vital data due to inevitable circumstances. However, like other backup application even the time machine could also be subjected to errors and issues which would cause severe threat to your backup copy. One of the most commonly encountered Time machine error is "The backup volume is read only". Due to this error you will not be permitted to store or backup new data to Time Machine drive until the error is fixed.
There are various solutions that help you troubleshoot this sort of time machine error. At times operating system assumes that the drive’s permissions are changed to read only mode. In such cases you can try resetting the permissions and fix the issue; but this method may sometimes fail and may not fetch you expected results.
Even turning off time machine would help you in solving the error. To do this you have to open System Preferences, click on Time Machine preference pane and then move the slider to OFF position. Suppose if you are using external hard disk as Time Machine backup volume then try to eject the drive from your computer and reconnect the drive or restart the computer.
In case the Time Machine drive isn’t mounted on Desktop then using Disk Utility (located in /Application/Utilities) you can unmount the drive to fix the issue. For this just select Time Machine drive from Disk Utility sidebar and then click on Unmount button situated in toolbar. After unmounting the drive, disconnect the cable and later you can plug in the drive; now the drive should work fine.
These are the most commonly used and an effective method to fix the backup volume is read-only error on time machine. However, if the error is not fixed at the earliest, it could lead to Time Machine failure causing huge data loss. In such circumstances, wherein you have lost your data, just use Remo Recover (Mac) software. The tool is specifically designed to perform data recovery after Time Machine failure in just few minutes. It supports data recovery from any Mac OS version including the latest Yosemite.