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How to format a 3TB GoFlex Home

Maybe you want to reformat the drive to start over or maybe you're upgrading to a larger drive, but the seagateshare web interface format option won’t work with 3TB drives and you can't use the USB adapter off a GoFlex Desk or Backup Plus, so how do you format a 3TB drive?

Seagate Support says they use “special software in the factory” to format these drives but that’s not very helpful. They also say you have to use MBR partitioning without explaining just how you’re supposed do that on a 3TB drive with 512 byte sectors.

If you have desktop PC you can use the great tip from David Vielmetter http://davidvielmetter.com/tricks/seagate-goflex-home-disk-maintenance/ to hook up the drive with SATA and partition the drive with a single 3TB GPT partition and format as NTFS with 4096 byte allocation unit (cluster) size..

But if, like me, you only have a laptop what are your options?

I had a 3TB Seagate Backup Plus v1 that I wanted to use on my GoFlex Home to replace the original 1Tb drive


Backup Plus 3TB

Why can't you use a GoFlex Desk USB adapter (or most USB-SATA adapters)?

Using a GoFlex Desk base (or Backup Plus v1) works great for sub 2.2TB drives, but for 3TB drives the USB-SATA bridge changes the logical sector size to 4k.

The GoFlex Home's native SATA connection has a sector size of 512 byte but if the drive is formatted on a USB dock all the addresses in the Master File Table are based on 4096 byte references and the filesystem can't be mounted. 
That's also the reason why a 3TB+ GoFlex Home drive can't be read in Windows using a USB dock. When you connect with USB using 4k sectors everything is in the wrong place so the OS says the drive needs to be formatted.

MBR just doesn't have enough "digits" for numbers over 2,199,023,255,040 so manufacturers get around that by messing with sector size. The GUID Partitioning Table (GPT) was invented to solve the large capacity problem without messing with sectors sizes and fortunately the GoFlex Home's Linux OS handles GPT.

Update: (Sep 2019) I came across a USB dock which supports both 512 byte and 4096 byte sectors. I am not recommending it, but if you are thinking of buying a USB dock to work with your GoFlex Home drive then one that does what this one claims is what you need. If you come across any other USB docks that support 512 byte sectors let me know in the comments and I'll add them to the list.
Use the 512B setting to have any hope of reading your GoFlex Home hard drive or to format your drive to work with your GoFlex Home.


How to use the GoFlex Home Linux operating system to partition and format the drive.

Log in with SSH and become root. Then use the Linux parted command to partition and format the drive (the commands you enter are in blue).

bash-3.2# /sbin/parted /dev/sda
GNU Parted 1.8.1
Using /dev/sda
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) mklabel gpt
(parted) unit TB
(parted) mkpart primary NTFS 0TB 3TB
(parted)
(parted) print

Model: Seagate ST3000DM001-1CH1 (scsi)
Disk /dev/sda: 3.00TB
Sector size (logical/physical): 512B/512B
Partition Table: gpt

Number  Start   End     Size    File system  Name     Flags
 1      0.00TB  3.00TB  3.00TB               primary


Reboot the GoFlex Home to mount the filesystem and you're done.

3TB GPT NTFS mounted
3TB NTFS GPT partition mounted and ready to use
Note that it only reports 2.73TB, but there's no missing capacity because 3TB is 2.73 TiB. (1 TiB = 1.099511627776 TB)


 UPDATE: If you follow these instructions and find that the msftres flag is set and can't be cleared and the NTFS filesystem won't mount, then click the following link to find out how to reset the msftres flag and create an NTFS filesystem with mkfs
(note: only use this alternative method if  you have the msftres issue because it requires creating a second partition and you lose 100 MB of storage space)