Move of time machine backup: unable to "restore" I want to use a new hard drive for time machine. I try to restore the old backup into the new disk using disk utility. It fails with the following error :


  source volume is read-write and cannot be unmounted, so it can't be
  block copied


Why ?
What can I do ?
Problem understood. The disks were actually locked by the failed copy of the backup folder I tried to do between the two disks shortly before. 

If it happens to you, just make sure the disks are not locked. In the worse case, reboot.