What Is A Partition?

Partition is a separate “part” of the hard drive resulting from a process called partitioning. Actually when we say “part” we mean some space that is less than 100% of the hard drive capacity. However, this may be a bit confusing because sometimes one partition can occupy the whole available space on a hard drive. As we know operating system will be able to write data to hard drive only when it finds partition with a valid file system. This could become possible only after formatting (formatting is the process of creating a file system) but more interesting here is that before formatting we must specify the amount of disk space that will be formatted. This will be the exact size of our new partition. If we choose the maximum available disk space, then our new partition will occupy the entire hard drive. On the other hand if you want you can always create more than one partition but remember that there are some limitations you should consider before partitioning your hard drive. Also note that various partitions could be of different type and file system, depending on their intended purpose. Below you can read more.

Partition Types.

Primary Partition.  Usually this partition is intended to store and boot the operating system but there wouldn’t be a problem if you wish to use it for data storage as well. In other words you can have a primary partition without any operating system installed on it but remember that you can create up to 4 primary partitions on a single hard drive with only one of them set as active.

Active (boot) partition.  Active or also called “boot” or “system” partition could be any primary partition that has an operating system installed on. When you install an operating system it automatically sets a marker in the same partition where the installation goes (usually this is C:\) indicating that there are the boot files for that OS. This marker tells BIOS that this is the active partition and the OS can be loaded from it. If you have two or more primary partitions only one of them may be set as “active” and what’s more only a primary partition can be marked as “active”, therefore you can not set a logical drive in an extended partition to be the “active” one. On the other hand you can install a second operating system (even on a logical partition) but in such a case BOOT files for that OS will be also placed in the partition marked as active. To help users most operating systems will install Boot manager allowing easy selection and launching of the various operating systems installed on a computer. Note that each hard drive may contain only one active partition so if you have two or more drives installed on your computer it will boot from the first active partition according to the disk boot order in the BIOS.

Extended partition. Extended partitions are mainly used to overcome the limit of 4 possible partitions on a single hard drive. This way you can expand the capabilities of your hard drive but remember that you can create a maximum of 1 extended partition on a single physical hard drive.  Actually, this is not exactly a partition but rather a container for the logical drives. It could be also represented as a virtual hard drive containing multiple partitions. You can not format extended partition or assign a drive letter to it, which makes it unable to store any data and therefore it doesn’t act as a real partition.

Logical drive.  Logical drive (or logical partition) can be created within an extended partition. You can format it or assign it a drive letter but you can not set it as active.  Logical partitions are typically used for data storage e.g. they hold files unrelated to the operating system like audio, video, documents, etc. There is a limitation of up to 24 logical drives created within a single extended partition but in most cases the use of so many partitions would rather cause an inconvenience than better organization.