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I ran gdisk on /dev/sdb, a 4TB USB external drive, and "gdisk -l" suggests I did it correctly: 

# gdisk -l /dev/sdb 

GPT fdisk (gdisk) version 0.6.6 

Partition table scan: 
  MBR: protective 
  BSD: not present 
  APM: not present 
  GPT: present 

Found valid GPT with protective MBR; using GPT. 
Disk /dev/sdb: 976754645 sectors, 3.6 TiB 
Logical sector size: 4096 bytes 
Disk identifier (GUID): 915A2474-7348-48FC-A436-64CE30DEE0B3 
Partition table holds up to 128 entries 
First usable sector is 6, last usable sector is 976754639 
Partitions will be aligned on 2048-sector boundaries 
Total free space is 2042 sectors (8.0 MiB) 

Number  Start (sector)    End (sector)  Size       Code  Name 
   1            2048       976754639   3.6 TiB     EF00  EFI System

However, gdisk didn't create /dev/sdb1 or /dev/sdb[anything].

How do I access the partition I presumably just created?

Notes:

  • I tried other partition types where it says EF00, but same problem.

  • I tried cfdisk (which DID create /dev/sdb1), but it didn't work, probably because the disk is > 2TB

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Sometimes newly-created partitions don't appear until you unplug and re-plug the disk (if it's removable) or until you reboot the computer (if it's an internal disk). This is most likely to happen if you're replacing existing partition(s) and if one or more of those is in use when you run gdisk (or fdisk or parted). Thus, I recommend you unplug the disk and plug it back in again. Note that if a partition was in use, it's best to unmount it before partitioning the disk. If you don't do so, the disk may reappear as /dev/sdc rather than /dev/sdb when you plug it back in.

Another possibility is that your kernel lacks support for GPT. This is unlikely on precompiled kernels that come with any but very old versions of Ubuntu, Debian, Fedora, OpenSUSE, and other major distributions; but if you're using a very old distribution or if you've built your kernel yourself, it might be missing GPT support. In this case, you'll simply have to upgrade your kernel, or fix the kernel options and recompile it.

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  • I unplugged and replugged and /var/log/messages said "sdb: unknown partition table", and I couldn't find a way to insmod part_gpt support (using Fedora 11), so I ended up just "mke2fs" on all of "/dev/sdb" (which worked fine), and writing what I just realized is a run-on sentence comment.
    – user59328
    Feb 17, 2014 at 14:31
  • If you got an "unknown partition table" error, then it sounds like your kernel doesn't support GPT. Fedora 11 is pretty old, although GPT support was definitely available in the kernel source at that time. It's plausible that Fedora's developers omitted it from x86/x86-64 builds, though, so I suspect that's the cause of the problem. Using the disk unpartitioned is certainly one way around the problem, although it's a bit limiting. You could also use LVM on the whole disk.
    – Rod Smith
    Feb 17, 2014 at 14:33

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