Partitions: Primary, Extended, and Logical

Check out that Oxford Comma up there.

Today I was repartitioning my new hard drive (a new external that I'm super stoked about) and I thought I might write up a post on the differences between primary, extended, and logical partitions. I used to wonder about the differences between those three right along with everyone else who asks this question on forums all over the interwebz. Somewhere along the way I figured out the difference (how often does one repartition their hard drive anyways). It probably had something to do with Arch Linux.

Primary partitions are what Windows uses by default (last I checked at least). Having nothing to do with Windows though, you can have a maximum of four primary partitions. To maximize the number of partitions on a drive, since you can only have one extended (we'll get to that in a minute), create three primaries (sda1-3) and a fourth extended to cover the rest of the disk. Since extended partitions have no unreasonable limit on the number of logical partitions they can have though, you might as well just do one big extended unless you have some reason not to.

An extended partition (or extended boot record) is effectively a container for logical partitions. There can only be one extended partition, but you can fill 'er up with logical partitions. When creating an extended partition, chances are you will want it to take the remaining space on the drive since it will contain numerous sub-partitions.

A logica many thanks to doingl partition is a sub partition of an extended. There is no maximum number as far as I know. The only limits are imposed by the partition manager you use. Rumor has it that fdisk will display no more than 60 logical partitions and people have gotten up to 126 using sfdisk. Even with an extended partition, you can still have three more primary partitions, so sdx1-4 remain reserved. Hence, logical partitions start at sdx5 and go on up from there.

My Current Partitioning Scheme
I currently have my partition set up to look something like this