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Document ID: YAST-3FJTR7

CrossBrand - Operating Systems - Optimizing hard drive space through drive partitioning

Applicable to: World-Wide

In DOS every file stored on a disk uses at least one allocation unit (called a "cluster") no matter what the size of the file. The size of a cluster depends on the size of the partition. The larger a partition, the larger each cluster on that partition. For example, if you have a 1.08 GB (gigabyte) partition, the cluster size will be 32K.

For example, on a partition where a cluster is 32K in size, a 62-byte file is going to "tie up" an entire 32K-cluster of storage space on your disk. In this example, there's going to be nearly 32K of space that cannot be used by any other file because it's been used to store this particular 62-byte file.

A typical mix of application and data files can include thousands of files. If each file leaves a few KB (kilobytes) of unused space in the form of a partially filled cluster, this can add up to several MB (megabytes) of unused, or wasted, space.

The only way to reduce the cluster size is to reduce the partition size.

The breakdown for DOS 4 and above is shown below:

FDISK Partition Size* Cluster Size



0 - 127 MB         2K



128 - 255 MB       4K



256 - 511 MB       8K



512 - 1023 MB     16K



1024 - 2047 MB    32K



* 1 MB = 1,048,576 bytes

Partition sizes are allocated in your setup (FDISK, Partition Magic, etc.) program. Repartitioning an existing drive with FDISK destroys all of the data (however, using one of the "partitioning" utilities on the market today can avoid this.) If repartitioning an existing drive, whether with FDISK or a partitioning utility, be sure to create a backup of the drive before starting. To maximize usable disk space it's recommended that you partition the drive in 127 MB, 255 MB, or 511 MB partitions.

Keywords: DOS DOS 4.01 Cluster Size

Search Keywords

DOS, Windows

Hint Category

DOS/Windows 3.x

Date Created

26-03-97

Last Updated

06-04-99

Revision Date

06-04-2000

Brand

IBM Aptiva, IBM ThinkPad, Cross Brand

Product Family

Aptiva, PS/1, ThinkPad 300, ThinkPad 310, ThinkPad 315, ThinkPad 340, ThinkPad 345, ThinkPad 350, ThinkPad 355, ThinkPad 360, ThinkPad 365X/XD, ThinkPad 365C/CS, ThinkPad 365CD/CSD, ThinkPad 365E/ED, ThinkPad 370, ThinkPad 380, ThinkPad 380D, ThinkPad 380E, ThinkPad 380ED, ThinkPad 380XD, ThinkPad 380Z, ThinkPad 385D, ThinkPad 385E, ThinkPad 385ED, ThinkPad 385XD, ThinkPad 390, ThinkPad 390E, ThinkPad 500, ThinkPad 510, ThinkPad 560, ThinkPad 560E, ThinkPad 560X, ThinkPad 560Z, ThinkPad 600, ThinkPad 600E, ThinkPad 700, ThinkPad 701, ThinkPad 720, ThinkPad 750, ThinkPad 755C/CS, ThinkPad 755CE/CSE, ThinkPad 755CX, ThinkPad 755CV, ThinkPad 755CD, ThinkPad 755CDV, ThinkPad 760C, ThinkPad 760E, ThinkPad 760CD, ThinkPad 760L/LD, ThinkPad 760ED, ThinkPad 760XD, ThinkPad 760EL/ELD, ThinkPad 760XL, ThinkPad 765L, ThinkPad 765D, ThinkPad 770, ThinkPad 770E/ED, ThinkPad 770X, ThinkPad 770Z, ThinkPad i Series 172x, PS/2

Machine Type

2134, 2144, 2159, 2168, 2176, 2011, 2121, 2123, 2133, 2155, 2615, 2600, 2610, 2620, 2618, 2619, 2625, 2624, 9545, 2635, 2636, 2626, 2603, 2604, 2640, 2641, 2645, 2646, 9552, 2630, 9546, 9547, 9548, 9549, 9544, 2627, Various

Model

Various

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