(SOLVED) 6 TB drive showing up as 2.7 TB. Can't initialize GPT (Win 10 64-bit UEFI)

[ccoulby]

I have two Seagate 6TB (4KN or 4K?) drives that are showing up in Windows 10 (in Disk Management) as 2794.51 GB. I attempt to initialize both drives using the partition style GPT and I get the following error: "The request could not be performed because of an I/O device error." It seems no matter what I try I cannot get the drive to initialize.

Now, that being said I ran Parted Magic and was able to mount, delete partitions, format the drive, and write files to the drive. Both drives showed up as the full 6 TBs.

Also, I seen a link on another post where it advised to run Windows setup and use Disk Part to convert the drives to GPT. I tried this and Disk Part also sees the drives as 2.7 TB.

I have contacted Seagate support and have't received much help as of now. I am willing to try anything to get this squared away.

About my machine: I am running my OS on 2 SSD drives configured RAID0 on SATA III ports. The two 6TB drives are on SATA II ports non RAID. I just reinstalled Windows 10 64-bit and made sure it was booting UEFI and ran the command (powershell confirm-SecureBootUEFI) in an elevated powershell command prompt to double check.

The specs are as followed:

ASUS Z77-A motherboard running the latest BIOS version.
Intel i7-3770
Samsung 850 Pro 250 SSD (x2) RAID0
32GB Kingston HyperX RAM (8GB) x4
Corsair RM 850 PSU
GeForce GTX 780Ti

I appreciate any help I can get and hopefully we can solve this problem together, because I am at a complete loss.

Thanks!

 

[drtweak]

UEFI isn't needed to use GPT partition on large drives it is ONLY needed if you are booting off a drive larger than 2TB.

Do you have any other SATA ports? Maybe the SATA controller it is on can't support that high. Sounds like it is at the 3TB limit to me for some reason.

 

[ccoulby]

drtweak thanks for your reply.

I just tried to remove all drives except one 6TB drive and I connected it to SATA0 which is a SATA III port. Still only recognized it as 2.7 TB in Windows setup using Disk Part.

In my opinion the limitation can't be the motherboard unless it is a Windows driver causing the problem. Reason: Parted Magic sees all 6TB of the drive even on a SATA II port.

 

[drtweak]

Yea well a 3TB drive is still seen as a 3TB drive even when formatted as MRB you just can't use it all.

So are you trying to install the OS to this drive or no? If you are not then I wouldn't even worry about formatting it at windows setup. If you are then that one i'm not too sure on. Looking around as we speak...or well type XD

 

[drtweak]

Yea can't find jack on a 6TB drive showing as a 2.7.

 

[ccoulby]

I have figured out the problem after hours upon hours of trouble shooting. In the BIOS I had changed the SATA mode from AHCI to RAID so that I could RAID0 my 2 solid state drives. For some reason this will not work with the 6TB drives. I turned the SATA mode back to AHCI and the drives work as they should.

Not the fix I wanted ( lost RAID0) but at the very least the 2 6TB drives are now working. Thanks for your help!

 

[drtweak]

Really? Wow. Maybe get a dedicated RAID card for the RAID 0 maybe? There are plenty of good but cheap cards that do just as good of a job and are just as fast and they will NOT affect your 6TB drive or the other way around.

 

[Michael_444]

one thing to check ... MAKE SURE YOUR BOOTABLE WIN 10 USB STICK IS FAT32/GPT

You must set the BIOS for UEFI boot and set up the RAID (whether RAID 0 or 5) as you would expect, but importantly - When you boot from your Windows 10 USB stick to load the operating system, the USB stick must be formatted with FAT32 and GPT.

It sounds odd but if the USB stick is NTFS and MBR, it sets up the Windows 10 install to initialise the disks as MBR and not GPT. So when you get to the disk partition page and you try and create a single partition bigger than 2TB it won't let you ... becuase it's secretly thinking you have a non-UEFI Bios because you originally booted from a USB stick that was MBR.

I struggled with this for a couple of days until I realised that when I created the USB stick from the Windows 10 64 Bit ISO using RUFUS-2.6 (a great program by the way), when I selected the Windows 10 ISO it cunningly reset the "Partition Scheme" dialogue box to MBR and the "File System Type" to NTFS. I simply could not get the RAID5 array to go beyond 2TB when booting from this USB.

When I forced it to GPT and FAT32 and recreated the USB Stick it all worked magically, just as you would expect ...

- Set UEFI in the BIOS
- Create the Raid Array (make sure you blow it away and redo it...)
- Boot from the USB stick (and this time when you see the boot options the USB stick will appear as a UUID / UEFI device)
- When you get to the windows disk partition part, you need to load the Intel RAID driver before selecting a partition and hitting Next - have it on the same, or another USB stick
- Select the unused partition and create one well over 2TB (mine was 5.7TB as I had 3x3TB Disks in RAID5) and lo and behold, it creates a couple of small system partitions for internal use and one big 5.5TB+ parition for Windows

Windows 10 then loaded perfectly

Happy Days

Hope this helps someone out there on t' interweb

 

[drtweak]

If you read his last message it was because the RAID didnt support larger tha 3TB for some reason and he wasnt installing windiws to these drives either.