Danatela is correct; however:

• It's common practice to use a primary partition for a single-partition disk like this. Although a logical partition will work for this purpose, it involves somewhat more complex data structures than a primary partition, those data structures end up reducing the size of the partition (by an admittedly minuscule amount), and there really is no need for a logical partition on a 1-partition disk, so you get no advantages from these small disadvantages.


• Your disk is 3TB in size. fdisk reports that it uses 4096-byte logical sectors, and on such disks, the MBR partition table that fdisk manipulates can handle disks that are up to 16TiB in size; however, most disks today still use 512-byte sectors, and on such disks, MBR isn't really good beyond 2TiB (or 4TiB if you push things and are willing to accept some limitations). As a general rule, on larger disks, you should use the GUID Partition Table (GPT), which you can create and manipulate with GParted, parted, or gdisk. (The very latest versions of fdisk can also handle GPT, but AFAIK no version of Ubuntu yet ships with GPT-enabled versions of fdisk.) Note also that GPT doesn't distinguish between primary, extended, and logical partitions, so if you were to use GPT, the preceding bullet point would become irrelevant.

Overall, there's no compelling reason to change what you've got; but I wanted you to be aware of these issues because the path you've taken is becoming obsolete.