Unable to mount a partition of external 3TB hard drive..GPT warning

Question

My external HDD has five partitions and I am able to mount 4 partitions except one (labeled office) which is of 1TB and has all my backups. I am providing more information below

fdisk -l
Disk /dev/sda: 750.2 GB, 750156374016 bytes
255 heads, 63 sectors/track, 91201 cylinders, total 1465149168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0xda73e482

   Device Boot      Start         End      Blocks   Id  System
/dev/sda2   *        2048      409599      203776   42  SFS
/dev/sda3          409600  1227823103   613706752   42  SFS
/dev/sda4      1227825150  1465147391   118661121    5  Extended
Partition 4 does not start on physical sector boundary.
/dev/sda5      1227825152  1432625933   102400391   83  Linux
/dev/sda6      1432627200  1465147391    16260096   82  Linux swap / Solaris

WARNING: GPT (GUID Partition Table) detected on '/dev/sdb'!
  The util fdisk doesn't support GPT. Use GNU Parted.


Disk /dev/sdb: 3000.6 GB, 3000558944256 bytes
255 heads, 63 sectors/track, 364797 cylinders, total 5860466688 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x00000000

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1  4294967295  2147483647+  ee  GPT
Partition 1 does not start on physical sector boundary.

GParted for the 3 TB external drive outputs the following:

/dev/sdb2: LABEL="New Volume" UUID="BA5EC1045EC0BA81" TYPE="ntfs" 
/dev/sdb3: LABEL="Rashmi" UUID="5822A0F722A0DB70" TYPE="ntfs" 
/dev/sdb4: LABEL="Legal" UUID="D6E048D5E048BD8D" TYPE="ntfs" 
/dev/sdb5: LABEL="Entertainment" UUID="C65E11415E112C25" TYPE="ntfs" 
/dev/sdb6: LABEL="Photos" UUID="CA1ADB271ADB0F77" TYPE="ntfs" 
/dev/sdb7: LABEL="Office" UUID="32588F11588ED2D1" TYPE="ntfs" 

I cannot mount /dev/sdb7, that is, the partition labeled "Office".

Solution

Many USB enclosures and USB/ATA adapters can't handle disks with more than 2^32 sectors. This works out to 2TiB, so disks larger than that often fail on such enclosures and adapters. If this is your problem, the only solution is to use the disk internally or via another adapter/enclosure -- perhaps an eSATA one rather than a USB one. (I've even heard of one enclosure that has both USB and eSATA connectors but that works differently depending on how it's connected -- a design that's sure to cause hair-pulling!)

If you need more help, post the exact error message you get when you try to access the failing partition, ideally from the command line. Also, post details about your enclosure or adapter -- its type (USB, FireWire, USB, eSATA, etc.), brand, model, etc.

Comments

[LATEX-GURU]

Thanks! oldfred. I had lost my Windows 7 while installing 14.04. So there was no way i can run chkdsk. However was able to see the partition after changing the flag which was showing as boot via Gparted and rebooting.

[oldfred]

I missed the SFS info with fdisk on sda. That is dynamic partitions which do not work with Linux. Generally best to remove the dynamic partitions, but you have to use third party Windows partition tools like EASEUS Partition Master or Partition Wizard. sevenforums.com/tutorials/… See also posts by oldfred & srs5694: ubuntuforums.org/showthread.php?t=1705481

[jeremiah]

I'm seeing the same message on a btrfs partition with GPT.

[LATEX-GURU]

Thanks Rod I was able to see the partition after changing the flag which was showing as boot via Gparted and rebooting. I had WD external HDD drive which i was using as USB. I have not completely resolved the issue but my understanding is as I was backing up a windows image in this drive it got flagged or converted into boot or GPT. Although unrelated, but since i was installing dual boot i have lost my windows now. I may have to start a thread for that or read old posts.