Advanced partition problem - My drive thinks its two physical drives

bradfordod · Jan 13, 2015

Hello, I botched a bootcamp install and had my hard drive replaced. The shop that replaced the hard drive said that they could not fix what was wrong. I am certain that there is a way to fix this.

I currently have the drive set up in an external case.

The drive actually thinks its two drives, not 2 partitioned spaces in one drive, but two physically separate drives. Here is what "diskutil list" brings up. The external drive is a three TB drive with identifier of disk1 and disk2.

/dev/disk0
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *751.3 GB disk0
1: EFI EFI 209.7 MB disk0s1
2: Apple_HFS Macintosh HD 600.0 GB disk0s2
3: Apple_Boot Recovery HD 650.0 MB disk0s3
4: Microsoft Basic Data BOOTCAMP 150.4 GB disk0s4
/dev/disk1
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *2.2 TB disk1
1: EFI EFI 209.7 MB disk1s1
/dev/disk2
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *801.6 GB disk2
1: EFI EFI 209.7 MB disk2s1

Similarly on a PC it also sees the drive as two drives.

I can combine both drives as a fusion drive and that makes it look and act like 1 drive, but deep inside it still thinks its two. I even tried to partition the fusion drive, that took about 9 hours as it resized the physical storage volume, but it still acted as if it was two drives.

Please help. I can take advice from a PC or mac standpoint. This is too strange for me.

APassingMe · Jan 13, 2015

I'm just guessing but I would say you need to do a full backup of your system and do a clean OS install, the purpose of the clean install is to allow you to recover after deleting both partitions and formatting your HDD with a new single partition. I'm a little sick at the moment so I can't run you through all the steps but it's pretty straightforward, you'll need the version of the OS you want to install downloaded to a usb drive and then you'll follow a clean OS X install guide while remembering to delete and format your partitions before beginning the install.

bradfordod · Jan 13, 2015

Its a bit beyond that. I tried all that before I brought it to the shop. The shop replaced the hard drive in my computer, so its currently in an external case with no operating system on it. I can reparation either of the drives that it thinks are physical drives, but I can not reparation the drives together as it thinks its two physically separate drives.

Its a hard situation to explain, I hope you understand what I mean.

APassingMe · Jan 13, 2015

That's weird, so your main computer HDD is fine at the moment but you're trying to repair the old HDD which is in an external case?

APassingMe · Jan 13, 2015

It sounds like you just need some software that will let you access the drive at the system level to reformat and make the changes, I'm really too sick to muddle through it right now though so I'm going to leave it to anyone else who wanders through. If it's in an external drive you can try formatting it with a windows machine.

bradfordod · Jan 13, 2015

Yes, I am trying to repair the old drive in an external case. Its a 3 TB drive, so I don't want to trow it away. I can use either the 2.2 TB portion or the 800GB portion, but I want the drive to be normal. I refuse to believe that this can't be fixed.

APassingMe :

bradfordod · Jan 13, 2015

I have tried to reformat with a windows machine, but thats not fixing the root problem, which is that sees the drive as two separate physical drives. I would have to agree that I need to access the drive as the system level, but that is bit beyond me and I am not sure what to look on on other forums.

I have tried deleting the the partition file system to try to force it to repair itself, but I can only do that to one of the drives at a time, there is not a master drive (as you would see on a typical partition) that I can reset.

APassingMe :

mbarnes86 · Jan 13, 2015

HI

Strange things can happen on old Intel pc's and usb trays (sata to usb chips) which can't support drives greater than 2 TB

Western digital data life guard for Windows probably can test this drive provided the usb tray or sata interface / PC support drives over 2 TB

This software can also erase the partition cylinder or first sector of the drive

Also under windows out of data Intel sata drivers can cause problems with drives over 2 TB

Regards
Mike Barnes

bradfordod · Jan 13, 2015

The drive won't even pass the quick test with that program. The drive again shows up as two separate drives, but both show up as 3TB, so thats some progress. Do you think doing a full erase would do anything, the quick erase didn't fix anything, and the full erase will take about 23 hours.

mbarnes86 :

popatim · Jan 13, 2015

Was this a seagate or wd from and external drive originally?

fzabkar · Jan 14, 2015

I suspect that the firmware inside the enclosure may be enumerating the 3TB drive as two physical drives, each with a capacity less than 2TiB, so that it can work with a legacy OS such as Windows XP or earlier.

If so, then I would check if a firmware update is available for the enclosure or its bridge chipset.

bradfordod · Jan 14, 2015

No its not

popatim :

bradfordod · Jan 14, 2015

Probably not that, one of them its 2.2TB and the other is 0.8TB.

fzabkar :

popatim · Jan 14, 2015

bradfordod :

2.2TB is the actual MBR limit, so what has been said makes sense and along the line of what I was thinking also.

fzabkar · Jan 15, 2015

See the answer by "sminlal" in the following thread:

http://www.tomshardware.com/forum/274015-32-external-usb3-drive-shows-devices

Large Capacity Drives Information Sheet:
http://www.wdc.com/wdproducts/library/WhitePapers/ENG/2579-771501.pdf

"USB attached storage solution providers have solved many of the issues associated with Large Drives within the USB Bridge firmware. Some present large capacity drives as single drive using larger sector sizes while others present the large capacity drive as one or more than one smaller drives to the host."

bradfordod · Jan 15, 2015

Yep thats got to be the issue

popatim :

bradfordod :

2.2TB is the actual MBR limit, so what has been said makes sense and along the line of what I was thinking also.

bradfordod · Jan 18, 2015

I bought a new external case that was good for 3TB and all problems solved!

Advanced partition problem - My drive thinks its two physical drives

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