Hello, Sorry for the late reply.
When i open console after the ejection i get the message:
01/11/2012 22:32:42.000 kernel: Failed to issue COM RESET successfully after 3 attempts. Failing...
01/11/2012 22:32:42.000 kernel: disk1s2: no such device.
Hope this gives a clue, i'm tearing my hair out over it. there is absolutely nothing wrong with the disk itself.
If i do a full shutdown and restart, it finds the disk again no problems, but if i simply choose to restart from the menu, it does not find the disk again.
Thanks for any help you can give on this. I have only been experiencing this issue since i upgraded to mountain lion.
Capacity: 1 TB (1,000,204,886,016 bytes)
Model: SAMSUNG HN-M101MBB
Serial Number: S2R8J90B815515
Native Command Queuing: Yes
Queue Depth: 32
Removable Media: No
Detachable Drive: No
BSD Name: disk1
Rotational Rate: 5400
Medium Type: Rotational
Bay Name: Lower
Partition Map Type: GPT (GUID Partition Table)
S.M.A.R.T. status: Verified
Capacity: 209.7 MB (209,715,200 bytes)
BSD Name: disk1s1
Capacity: 999.86 GB (999,860,912,128 bytes)
Available: 648.66 GB (648,662,093,824 bytes)
File System: Journaled HFS+
BSD Name: disk1s2
Mount Point: /Volumes/living room
Volume UUID: D6125397-BAE7-3496-9B9C-6534EEE0B660
Not sure what else you could try. Formatting the drive did it for me. You could try swapping the drive into the other bay, in case that makes a difference, although I'm not sure why it would. Did you use the mac os x extended journaled option when formatting, using a GuiD setup? I also found that after it had ejected, I didn't have to remove the drive, just power off, and then restart. However just selecting restart from the OS X menu would not bring the disk back, it had to be a cold boot from power off for it to see the disk again.
If you have the patience you could reinstall OS X from scratch after having formatted both disks, just so as to be sure nothing spurious has been left in the system. Otherwise the only other thing I can suggest is a trip to the Genius Bar, although I'm not sure what help they'll be in this situation.
Hope you find a solution soon. I may have just struck it lucky, as all I did was reformat the drive.
I found that the reason it was happening to me was that the mac was still seeing the drive as an optical drive and because I had the power save options set to turn off discs when not in use, it kept turning it off in a way such that the OS thought it was ejecting. I just set the power save feature to never turn disks off. Which isn't really the solution I was after but it worked.
lol, only just seeing the comments.
thanks guys for finding the problem and solution.
I ended up replacing the internal drive (and upgraded to mavericks) a while back but still kept hold of the drive with the issue.
I ran a few tests on it and could not find any issues. Good thing I did not throw it away!
So looks like I can now go back to using the drive ... in an external enclosure