Volume erase failed: Media kit reports not enough space on device

Question

I was having problems with the external drive where I store my Time Machine backups, so I tried plugging and unplugging the drive (per earlier advice, and something that had worked in the past), but could not mount the drive. I ran Disk Utility and tried to verify the disk, which told me the disk needed to be repaired. I tried to repair the disk only to get an error message that Disk Utility could not repair the disk and it needed to be reformatted. So I tried to erase the disk with Disk Utility only to get the error message "Volume erase failed: Media kit reports not enough space on this device for requested operation". I am not sure what else to try at this point and could not find any similar questions here.
The drive in question is a 3TB USB Seagate Backup + Desk Media, formatted as Mac OS Extended (Journaled). It's divided into two partitions, one of which (2.2 TB) holds only Time Machine backups of my desktop and laptop and the other of which (800GB) is formatted similarly with some files stored on it. I was able to verify and repair this other partition. I'm running Disk Utility 13 on an iMac (2.8 GHz Intel Core 2 Duo) running OSX 10.8.5
Any suggestions for what to try next would be appreciated.

Answer 1

Just to let you know I appear to have the *exact* same problem, even down to the 3TB hard-drive in question.
I read recently that a time machine backup should have its own physical hard disk, not a separate partition on an otherwise-used disk. I wish I'd known that in advance of buying the external drive, as I would not have invested in a 3TB one if I had known I could only use it for Time Machine alone.
Dianeoforegon does make a fair point, though, in saying that all backups in one place is asking for problems down the line.
Incidentally, this Time Machine problem first started occurring when I upgraded to Mavericks. 9 times out of 10 my Time Machine partition would go corrupt for no reason. This definitely hadn't been happening at all before Mavericks. That same upgrade also killed off my entire Boot Camp partition, which caused me major headaches and I eventually had to simply reformat that partition and start again.