A 100-Gigabyte drive partitioned as a single partition does not have twice the available storage space as a 50-Gigabyte. The problem is that huge partitions have huge amounts of slack space. Slack space is the difference between the acutal size of a file and the space allocated to it by the OS.
On a 100-Gigabyte drive, partitioning is of great importance. I wrote the following article when much smaller drives were predominant; but, the same principles apply to your 100-Gigabyte disk. Proper partitioning on such a large disk will be very important to you so I suggest also that you get an understanding of slack space vs. partition size.
There is a Partition/Cluster/Slack table below; but, because of HTML formatting, columns are lost. You'll have to reconstruct the columns for yourself.
The article is pasted below:
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A 32-Gig drive can store as much data as a 38-Gig drive. This is not an article on compression, either. Compression is not a factor. If disk space is not important to you, don't read any further. The size of partitions on a hard disk is the most important factor in having the maximum total storage space.
Slack Space as Related to Cluster and Partition Sizes:
Usable drive space and total drive space aren't the same in a FAT system. The Windows FAT32 system divides the hard disk space into clusters and uses a File Allocation Table (FAT) to keep track of which data is stored in each cluster. Cluster size is related to partition size. The following is a table giving the various partition sizes and their corresponding cluster sizes.
Partition Cluster Slack
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Up to 7.9-Gig 4K 1%
8 to 15.99 8K 3%
16 to 31.99 16K 7%
32G to 2TB 32K 14%
The above table agrees with Upgrading and Repairing PCs, Eleventh Edition, Page 1402 by Scott Meuller, a recognized authority. However, my own experience has taught me that there are variances from this table. Slack space is more directly tied to cluster size, not partition size. Partition size is important only in the sense that larger partitions generally use larger clusters (allocation units).
Slack space will vary from hard disk to hard disk, depending on the data the user stores and the programs loaded; however, unless the system is used for something highly unusual, that variance is extremely small, overall.
Definition of Slack: The difference between the storage space a file actually needs and the space allocated to it in the FAT.
Only one file or portion of a file can be stored in a single cluster. No two files can occupy space in the same cluster. If a file only 1 byte in size is stored in a cluster, it will be allocated a full 16 Kilobytes of space by the FAT in a 16-Gig partition. If a file is 16K plus 1 byte in size, it will occupy one complete cluster plus one byte in another cluster for a total allocated space of 32K. So, a file 16K+1byte takes 32K of disk space. The remaining space in the second cluster is "slack" space.
Most files on a hard disk are very small and almost none have sizes that leave no slack space. So, slack space should be considered when choosing how to partition a hard disk.
Example: two single 15.99-Gig partitions will store about the same total data as a single 38-Gig partition.
The math:
38-Gigs x .72 (100% total space minus 28% slack space or 72% usable space) is 38 x .72 = 27.4 Gigs of usable space.
two 15.99 Gig partitions (32-Gigs when rounded) have only 14% slack space. So, 32 x 86% (usable) = 27.52 Gigs of usable drive space.
So, a 32-Gig drive divided into two 15.99-Gig partitions will store about the same total data as a 38-Gig drive partitioned as 38 Gigs.
