Disk-space management.

Judging by my e-mail, disk partition management is a very popular - but much misunderstood - topic. To help dissipate the mist, I'll discuss how partitioning affects overall system resource availability. Then I'll talk about some products that help manage those resources in a more efficient manner than operating-system-only tools: Partition Magic, System Commander, Remove-It, and the OS/2 Boot Manager.

Should you care about disk partitioning? Not if you have a high-capacity hard disk with no danger of running out of space, and you run a single operating system. But if you want to run more than one operating system on a single machine, maximize space-utilization efficiency, provide better organization of data, or add additional hard drives, then you'll want to understand this discussion.

How partitioning works

Any given physical drive can be divided into several sections called partitions. A given drive may have as many as four partitions. There are two types of partitions: primary and extended. In general, you can think of primary partitions as bootable, and extended partitions as for data. You can subdivide the extended partition into logical drives, but you cannot subdivide a primary partition. Both types of partitions can be either hidden or visible. Hidden means that the partition will be ignored by the operating system when booting, and inaccessible thereafter. The main differences between primary and extended partitions are summarized in Table.

All partition information (where it starts, where it ends, whether it's visible, its type, and so on) is stored in a data structure near the physical beginning of the disk. That data structure is called the Partition Table. You can view it using various utilities, including DOS's FDISK, the Disk Editor in the Norton Utilities, and several of the utilities discussed below.

In …