Why Use GPT fdisk?

by Rod Smith, rodsmith@rodsbooks.com

Last Web page update: 3/20/2010, referencing GPT fdisk version 0.6.2

If you want or need to use GPT, you have relatively few choices for partitioning software. Under Linux, libparted and the programs that use it (GNU Parted, gparted, and so on) have been your only real choice for a while. As of early 2009, these programs have worked, but have also suffered from several problems. For instance, as of GNU Parted 1.7.1, when creating a partition with a FAT filesystem, Parted marks it with a Microsoft Reserved partition type code, which makes the partition inaccessible to both Windows and Mac OS. As Homer Simpson would say, d'oh!

To work around such problems and to satisfy personal curiosity about GPT, I wrote gdisk. This program's user interface is modeled after that of Linux's fdisk utility for manipulating MBR disks, although gdisk necessarily deviates from fdisk in many respects. I subsequently added the sgdisk command-line-driven version of the program, as well.

Compared to GNU Parted, GPT fdisk has several advantages and disadvantages. Broadly speaking, you should consider using GPT fdisk if:

• You don't mind using relatively new software. GPT fdisk is currently only at version 0.6.2. I don't know of any current bugs that are likely to cause data loss, but I cannot guarantee that such a bug doesn't exist. You should be particularly cautious when using the program on a disk with existing partitions that hold valuable data.
• You use Linux, FreeBSD, Mac OS X, or Windows. Each OS seems to have it own way of doing certain important low-level disk tasks, such as determining the disk size, so GPT fdisk must be explicitly customized for each OS it supports.
• You want more precise control over your partitioning than Parted provides. For instance, gdisk provides sector-exact control of partition sizes and it enables you to enter any arbitrary GPT partition type.
• You want better control over recovery operations in the event that a corrupt partition table is encountered.
• You want to convert an MBR disk to GPT format. GPT fdisk permits doing this, although doing so will require you to re-install your boot loader (if it's a boot disk). Do not attempt to convert a Windows boot disk from MBR to GPT form unless you're an expert!
• You want to convert a disk that uses BSD disklabels to GPT format, or you want to convert a BSD disklabel within an MBR or GPT partition, into GPT partitions. This conversion is more trouble-prone than the MBR conversion, but it works in many cases.
• You want to back up and restore your partition table to or from an ordinary disk file.
• You like fdisk's simple text-mode interface.

Chances are you'll be happier with GNU Parted or its GUI cousins if:

• You want a stable and mature program. (Note, however, that one of my motivations for writing gdisk was glaring bugs in Parted. I suspect Parted's GPT code is relatively untested compared to its MBR code.)
• You prefer a GUI interface for partitioning. (This is true only of gparted, qtparted, and the like; GNU Parted is text-based.)
• You want to create filesystems at the same time you create the partitions that hold them.
• You want to resize or move filesystems along with their partitions.
• You want to use the software on any OS but Linux, FreeBSD, Mac OS X, or recent versions of Windows. (You can use partitions created by GPT fdisk on other OSes, but the program itself runs only on Linux, FreeBSD, Mac OS X, and Windows systems.)

Overall, I believe gdisk will appeal to those who like to use simple tools that provide relatively direct control over the things they manage. If you prefer fdisk to Parted on MBR disks, you'll probably prefer gdisk to Parted on GPT disks.

GPT fdisk originated on Linux, and Linux remains my main development platform. If you use another OS, you may want to compare GPT fdisk to your own platform's partitioning tools, so the preceding comparisons may not be very relevant. Compared to OS X's Disk Utility, GPT fdisk provides a great deal more precision and flexibility, but as Disk Utility is a GUI tool, it's much more accessible to those with moderate technical skills. Similar comments apply to Windows' native GUI partitioning tools. FreeBSD, OS X, and Windows all provide their own text-mode GPT partitioning tools with more flexibility than their platforms' native GUI tools.

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