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How to get around the 2.2TB with MBR partitions - Last Modified 2014-11-05 04:38 UTC - Created 2014-11-05 04:38 UTC

Most sites advise you to use GPT which I recommend as well. However, I ended up with an odd situations where my external USB 4TB and 5TB drives were not using GPT and still had single partitions that were 4TB and 5TB or well over the 2.2TB limit.

How? Turns out using newer versions of fdisk (cfdisk does not work so well) (fdisk in Ubuntu 12.04) results in it using 4096 byte (4KiB) sector sizes and thus allowing larger partitions. Evidence of this is in the following output from my actual Linux system:

[email protected]:~# dd if=/dev/zero of=/dev/sdc bs=1G count=1
1+0 records in
1+0 records out
1073741824 bytes (1.1 GB) copied, 9.97826 s, 108 MB/s
[email protected]:~# sfdisk -R /dev/sdc
[email protected]:~# cat /proc/partitions
major minor  #blocks  name

   8        0    7831552 sda
   8        1    7831521 sda1
   8       16 3907018580 sdb
   8       17 3907017556 sdb1
   8       32 4883770580 sdc
[email protected]:~# fdisk /dev/sdc

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

Note: sector size is 4096 (not 512)
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0x870e9389.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.

Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

Command (m for help): n
Partition type:
   p   primary (0 primary, 0 extended, 4 free)
   e   extended
Select (default p):
Using default response p
Partition number (1-4, default 1):
Using default value 1
First sector (256-1220942644, default 256):
Using default value 256
Last sector, +sectors or +size{K,M,G} (256-1220942644, default 1220942644):
Using default value 1220942644

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.
[email protected]:~# parted -l
Model: hp v125w (scsi)
Disk /dev/sda: 8020MB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number  Start   End     Size    Type     File system  Flags
 1      31.7kB  8020MB  8019MB  primary  ext2         boot


Model: Seagate Expansion Desk (scsi)
Disk /dev/sdb: 4001GB
Sector size (logical/physical): 4096B/4096B
Partition Table: msdos

Number  Start   End     Size    Type     File system  Flags
 1      1049kB  4001GB  4001GB  primary


Model: Seagate Expansion Desk (scsi)
Disk /dev/sdc: 5001GB
Sector size (logical/physical): 4096B/4096B
Partition Table: msdos

Number  Start   End     Size    Type     File system  Flags
 1      1049kB  5001GB  5001GB  primary

[email protected]:~# uname -a
Linux nas 3.5.0-23-generic #35~precise1-Ubuntu SMP Fri Jan 25 17:13:26 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
[email protected]:~# cat /etc/os-release
NAME="Ubuntu"
VERSION="12.04.4 LTS, Precise Pangolin"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu precise (12.04.4 LTS)"
VERSION_ID="12.04"