MBR to GPT - Seagate Barracuda ST3000DM001 3TB 7200 RPM SATA 6.0

Hi Everybody, :hello:

Up front, I don’t mean to be curt with you fine individuals but please do not bother answering this post unless you know what I’m writing about or you know the solution. I can’t be the only person that thinks it’s a pain and waste of time reading through junk information, multitudes of half-baked answers from fellow geeky know-it-alls (there’s a lot of those about this particular issue/topic). There it is. :non: Yeah, I said it.

Here’s a New Year’s Resolution: if you are guilty of aforementioned disruptive behavior, in the New Year please endeavor to reduce your internet tech forum e-waste by 20%. That doesn’t seem so bad, does it? I will do 20% less complaining about people like you, and the world will thank me and they will thank you too. Deal? Deal. :whistle:

OK, I purchased a 3TB Seagate Barracuda internal HDD hard drive. I intend to use it for storage only; it will not run the OS and I don’t want it to, ever. A separate SSD hard drive is devoted to the OS and programs in this system.

Out of the box the 3TB Seagate Barracuda internal HDD hard drive is formatted MBR as opposed to GPT. So, I converted it to GPT as that is supposed to override the 2.2TB size limitations of the MBR partitions. My understanding is that if you leave one of these 3TB hard drives as is and use it within an OS like Windows 7, it cuts the drive into a minimum of 2 partitions, one is 2.2TB and the second is 800GB.

I do not need nor do I want 2 partitions as this 3TB internal hard drive is strictly for storage. So, using a live disk of Parted Magic 64-bit I mounted the 3TB Seagate Barracuda drive and opened a terminal. I entered “gdisk” and it immediately printed a message that said the hard drive was detected as MBR and would be converted to GPT. So I followed the instructions for converting the hard drive from MBR to GPT, entering the commands to set the configuration. Once the parameters were all set and configured to convert from MBR to GPT and create 1 partition that is 3TB, I hit “w” and then enter, which runs the command and exits. Supposedly this created a GPT hard drive and I don’t have to worry about MBR partition size limitations anymore. So I open up GParted from within Parted Magic and set it to write to the 3TB internal hard drive one NTFS partition for the full size of the now GPT formatted hard drive, which should be 3TB.

I logged into Windows 7 and noticed that the hard drive shows up in “My Computer” as a 3TB hard drive. So I thought I had successfully accomplished what I had initially set out to do. :wahoo:

Moving forward, I have one 500GB MBR external hard drive that has seen a bit of use, it is aging and it is nearly full. Using Parted Magic I wanted to sync that data to that 3TB Seagate Barracuda internal hard drive that had been converted to GPT.

Again, using the live disk of Parted Magic 64-bit I mounted the 500GB MBR external hard drive and mounted the GPT 3TB internal hard drive. I opened a terminal and entered the command “rsync -av /media/(directory name of 500GB external hard drive) /media/(directory name of 3TB internal hard drive)/(directory name of 500GB external hard drive)” then hit enter and the command started chomping away, syncing the data to the 3TB internal hard drive. :D

As it was executing that command, I noticed something over on the “Mount -gtk” dialog in Parted Magic. It listed the 3TB GPT Seagate Barracuda internal hard drive like this, “Model: ATA ST3000DM001-1CH1 (2TiB, ntfs).” So, what’s up with that? :??: It lists the GPT internal hard drive as 2TB when it is 3TB, and I went through all of the above steps to make sure that did not happen.

It’s likely something stupid on my part. So feel free to chew me out if I missed a step or mixed something up in there. I’m just sort of scratching my head over here, wondering what the hell happened. :fou: Is it a glitch that is causing it to display a size of 2TB in Parted Magic, even though in reality the hard drive has a 3TB capacity? Was Windows 7 being deceptive when it displayed that there was only one GPT partition of 3TB? :??: Does it actually have the minimum 2 MBR partitions, one 2.2TB and one 800GB? Am I back to where I began? Do the commands in “gdisk” execute successfully when converting 3TB hard drives from MBR to GPT? :(

Please help!


PS. "I have written you a long letter because I did not have time to write you a short one."
7 answers Last reply
More about seagate barracuda st3000dm001 7200 sata
  1. ilysaml said:

    Motherboard model for this system: GIGABYTE GA-Z77X-D3H.

    Thanks for the link.

  2. gogogorski said:
    Motherboard model for this system: GIGABYTE GA-Z77X-D3H.

    Thanks for the link.


    Update your chipset drivers, update to the latest BIOS. Download Seatools and see how it reads your HDD.

    A 3TB HDD can never be formatted as MBR out of the Box, also use Acronis Disk Director and see how it reads your HDD.
  3. Seagate's 3TB GoFlex drives and WD's 3TB My Books are formatted as MBR out-of-the-box. The way they get around the 2TiB MBR limit is by using a sector size of 4KB rather than 512 bytes. This allows them to be compatible with Windows XP.
  4. Good to know.
  5. It sounds like you went the round about way to do this. Windows 7 should be able to handle all of what you did. You could have used the disk management in windows to delete all partitions on the drive then create any new partition(s) as GPT and format the drive. Afterwards you could have done a straight disk copy from one drive to the other using windows file explorer.


    Q. Can Windows XP x64 read, write, and boot from GPT disks?

    A. Windows XP x64 Edition can use GPT disks for data only.

    Q. Can the 32-bit version of Windows XP read, write, and boot from GPT disks?

    A. No. The 32-bit version will see only the Protective MBR. The EE partition will not be mounted or otherwise exposed to application software.

    Q. Can Windows 7, Windows Vista, and Windows Server 2008 read, write, and boot from GPT disks?

    A. Yes, all versions can use GPT partitioned disks for data. Booting is only supported for 64-bit editions on UEFI-based systems.
  6. I expect that Windows 7 may be having difficulty with 4KB sector sizes. I don't know how Disk Management handles 4Kn drives, but Win 7 Backup doesn't know what to do with them.

    ISTR that users of GoFlex and My Book drives have had to use either DiscWizard (Seagate's OEM version of Acronis True Image) or WD's SmartWare when repartitioning their drives. In any case the OP's drive should have worked as is, straight out of the box, no repartitioning or reformatting required.
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