Copy of NTFS partition is RAW !!!

You write that the same operation worked well on a 2TB drive but had the problem on the 3TB drive. I would suspect some compatibility problem of the 3TB hard drive with the system.
There are often problems from older BIOS, older chipset versions, controller compatibility issues, operating systems and drivers. However, you write that Linux (Ubuntu and Parted Magic) doesn't have any problem to access this drive and new partitions in this same computer. This means most probably that there is no hardware compatibility problem. Is there any driver problem with that windows version perhaps?

Some other things to investigate:
Did you try to mount the external hard drive to another windows computer?

The legacy Master Boot Sector partition table (msdos type) doesn't support 3TB disk space (GPT is needed for this), however this wouldn't prevent the hard drive to work in the first 2 TiB space.

Another thing could be the partition UUID. The UUID of the copy is the same as that of the original partition. This can cause mount problems.
Please, give a look at the GParted Manual concerning the copy & paste operations:
http://gparted.org/display-doc.php?name … -partition

Concerning the fast copy time: it is perhaps the result of a faster interface. Older USB drives were USB2; late big drives are very often USB3, that is much faster. Check it, please.

Concerning the 2TB drive limit with certain BIOS, I saw on http://www.maximumpc.com/article/ask_do … tb_ceiling or pcmag.com/article2/0,2817,2373641,00.asp that this limit only applies to boot partitions, not all drives. This is because the MBR can’t allocate addresses to partitions with more than 2.19TB worth of 512-byte blocks. Thus, the 3 following conditions must be fulfilled to be able to boot from a >2.19TB drive: a motherboard that uses Extensible Firmware Interface (or EFI) instead of the 32-bit BIOS, a GPT-initialized drive (as opposed to MBR), and a 64-bit OS. In my case, this should not be a problem since this 3TB HDD is not intended to be a boot drive, and the largest partition I need to create on it is just 1TB.

Concerning the copy time, actually both the 2TB and the 3TB drives were USB3, so this should not make any difference. Now I made a new copy of the 1TB ntfs partition on the external USB3 2TB drive using GParted, and it lasted only 23 minutes (and Windows 7 could access it all right)! So it looks like the copy time was reduced compared with what it was before reinstalling the computer, but I can't think why. On the other hand, the smaller and much emptier 750GB ext4 partition still requires about 3 hours for copying... The newest 1GB drive is SATA3 while the older 750GB is SATA2, but the motherboard is only SATA2-compatible, so it shouldn't make any difference. The new disk is also supposed to have shorter access time, but certainly not by a factor of 10! Anyway, this is not the real problem.

On Windows 7, before partitioning the 3TB drive, two volumes could be seen, the 1st one having 2TB in size and the 2nd one the rest. I found out on the manufacturer's web site (LaCie) that the disk should be converted to the GPT file system before partitions greater than 2TB can be created (which is not what I intend to do), so I did that conversion in Windows Disk Management (just in case...), and after that, the disk was seen by Windows as a single 3TB volume (unpartitioned). Then I re-tried the copy of the 1TB partition using GParted within Parted Magic. It lasted for 16 minutes as before, but is still not recognized in Windows 7 (it's RAW, as before). GParted now sees a 128MB partition at the beginning of the drive, which I assume is the "Partition table header LBA 1" (see en.wikipedia.org/wiki/GUID_Partition_Table) with type 'unknown' and flag 'msftres'.

So it looks like the 3TB disk is really the problem since the 2TB works fine, but I still don't understand why. It shouldn't be the BIOS either since all partitions can be accessed under Linux on the same computer and it shouldn't be Windows 7 since it can create partitions on this drive and access them properly. So it is a combination of using a 3TB drive (LaCie P9230), GParted creating (copying) the partition, and Windows 7 trying to access this partition that creates the problem. Any idea what the solution might be? I'm clueless, so thanks for any hint.

I just tried on a completely different Windows 7 32bit computer, but the problem is exactly the same as on my own Windows 7 64bit machine.

Now that the 3TB external USB drive has been converted to GPT file system, both the NTFS and the EXT4 partitions are seen as "RAW" in Windows 7 (as before in the NTFS case). The only difference I can see in GParted's disk information when using the 3TB disk instead of the 2TB disk is that the block size is 4096 bytes instead of 512 bytes (whether the disk is converted to GPT in Windows 7 before or not, GParted automatically uses 4096 bytes on 3TB disks, which makes sense since you cannot use a full 3TB disk with 512 bytes blocks.

So I'm still at the same point: any combination of "disks/read OS/partition creation software" works well, with the exception of the combination "3TB disk/Win7 for access/GParted for creating". As mentioned in my previous message, any other way is fine (Win7 can access the partitions it creates on the 3TB disk, Linux can access the GParted copy on the 3TB disk, etc.).

Could it be due to the different block sizes between the original partition (512 bytes) and the copied partition (4096 bytes) that could make the GParted copy less compatible with Win7? Any idea is welcome!

Yes, I created in GParted a 3TB NTFS partition spanning the whole volume, and Windows 7 can use it all right.

That now seems to be the correct explanation, indeed.

GParted automatically defines 4096 blocks on that drive, without option for the user to change that parameter (or I did not find that option). I just made a quick search on internet to see whether there is any possibility for the specific 3TB drive I'm using (LaCIe P'9230), but I couldn't find anything. I'm still going to investigate further and update the information here if anything new appears.

In the mean time, if someone with an "insider knowledge" of GParted knows what could be the precise reason for that copy-incompatibility, I would be interested (and the developers even more so I suppose).