Slack space or sometimes referred to as file slack is the areabetween the end of a file and end of the last cluster or sector used by the file in question. Area is an area that will not be used again tostore the information there, so the area is "wasted" useless. Slackspace is common in file systems that use a large cluster size, while the file system that uses a small cluster size can organize the storage media more effectively and efficiently. Amount of wasted disk space can be thought is estimated by multiplying the number offiles (including the number of directories) with half the size of acluster. For example, a 10 000 personal computer that stores files in a file system that uses a cluster size of 4 kilobytes will haveapproximately 10 000 x 2 MB ~ = 20000 KB. On a large file server,slack space and even reached the size of tens of gigabytes.
The unused space in a disk cluster. The DOS and Windows file systems use fixed-size clusters. Even if the actual data being stored requires less storage than the cluster size, an entire cluster is reserved for the file. The unused space is called the slack space.
DOS and older Windows systems use a 16-bit file allocation table (FAT), which results in very large cluster sizes for large partitions. For example, if the partition size is 2 GB, each cluster will be 32 K. Even if a file requires only 4 K, the entire 32 K will be allocated, resulting in 28 K of slack space. Windows 95 OSR 2 and Windows 98 resolve this problem by using a 32-bit FAT (FAT32) that supports cluster sizes smaller than 1K.
DOS and older Windows systems use a 16-bit file allocation table (FAT), which results in very large cluster sizes for large partitions. For example, if the partition size is 2 GB, each cluster will be 32 K. Even if a file requires only 4 K, the entire 32 K will be allocated, resulting in 28 K of slack space. Windows 95 OSR 2 and Windows 98 resolve this problem by using a 32-bit FAT (FAT32) that supports cluster sizes smaller than 1K.
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