Copying .avi files from Imac to external WD Hard Drive

You need to keep a good amount of free space on the internal drive (the startup volume). 16GB free is too low. Mac OS X uses the free space on the startup volume for hidden system files that are part of its normal operation, including things like virtual memory swap files. Finder copy processing probably also writes hidden temp files into the free space. You should try to keep 10% of the total space free, as a minimum; I use 15% as my minimum, although I've off-loaded most of my personal files to an external FireWire drive, so I have more than 50% free these days.

For your current situation, I would copy some other smaller files (or folders with smaller files) to the 1TB external drive, and erase them off the internal drive. I think the problem is that those .avi files are really large, and that may be a problem with your current lack of free space. So copy over some smaller files first, to get the free space up to about 50GB. Then, try to copy those large files again, starting with any that are on the smaller side. Once you delete them off the internal drive, you will have plenty of free space. You can copy back some of those smaller files you copied over initially (to free up space), if you want to do so, since you should have plenty of free space now.

And remember not to ever get the free space on your startup volume down to 16GB going forward.

Be sure to use the Partition tab in Disk Utility. In addition to formatting it as +Mac OS Extended (Journaled)+, you need to make sure the +partition map scheme+ is changed to *GUID Partition Table*. If that is a Windows PC formatted drive, the +partition map scheme+ will be *Master Boot Record*.

The setting for +partition map scheme+ is under the Options button on the Partition tab.

Sorry, did not notice your reply...

If you are still monitoring this topic, for your purposes (to avoid re-copying everything again), no.

In order to change the partition map scheme and formatting, you basically have to erase the entire drive.

Disk Utility in Leopard can add and remove partition on-the-fly, but the existing partition(s) must remain as is (current formatting) and the partition map scheme of the overall drive is not changed.

Before you reformat, realise that a FAT32 formatted drive is mac-compatible, because that is the file structure that macs are built to deal with. A new mac will be incapable of writing to disks formatted in any other way (although they are able to read NTFS-formatted drives). With a (free) third party piece of software macs can read and write NTFS (search "macfuse" or "NTFS-3G").

Because your mac's internal HDD is formatted in FAT32, you may be unable to copy files greater than 4gb off it, even if you are copying onto an NTFS formatted drive with the use of aforementioned third party software. I have had this problem and was searching for a solution when I came upon this thread.

Thedesolateone, Welcome to the discussion area!

Because your mac's internal HDD is formatted in FAT32...

Sorry but that is not correct. The Mac's internal drive is formatted HFS+ not FAT32.