I have an external 3TB hard drive formatted with MacExtended Journaled that I am using as my Time machine backup for my MBP. It is partitioned into two 2 partitions. One partition seems top work normally, I can access it, write to it, however it won't eject. In Disk Utility the non-functional partition(TM backup) appears as grayed out. I can get info on it, but it does not respond to Mount, Repair, or Erase. Both Repair and Erase result in operation failure messages. I've also tried to unmount the other partition which I can't do, and erase the entire drive. Trying to erase the entire drive, results in a failure message. It never gets past the "unmounting the drive" first step. I have also unplugged it and plugged it back in, I have restarted my Mac. Any ideas? Or I need to get a next external drive? See my signature for hardware info. Thanks! Update: Soon after posting this, somehow the partition that would not unmount, finally did unmount, and I was able to erase the entire disk and repartition it. What happened? I don't know. Is there anything else I should check? Thanks!