A data cluster on a computer is a group of memory sectors that are organized together based on files stored in the computer, and the cluster will emulate the size of the saved files. Creating a data cluster makes it easier for the computer to process and manage sectors, because managing a lot of small sectors can be difficult. Sectors do not need to be next to one another to exist in the same cluster. One problem with this is that memory fragmentation is common, especially with smaller files.
Computer memory has many sections, called sectors, and these sectors are among the smallest groups of memory on the computer. When a file is saved on the computer, it commonly will need more than one sector, because the sectors typically are very small. A data cluster is the memory used to save that file. The cluster has roughly the same amount of memory as the file being stored, so clusters are dynamic and organized based on what they are holding.
The advantage to using a data cluster is that it improves access speeds when the user opens the file. Without clustering, the computer would have to remember each and every sector where the file is stored, and this can be tedious. By treating all these sectors as one cluster, the computer can quickly locate that cluster, which enables the file to be retrieved faster.
A computer organizes a data cluster as a group, so it would be sound to think the sectors have to be next to one another. This is not how the computer works, though, because the sectors can be spread across different layers and areas of the computer memory. All clustering does is collect the location of each sector so they can be saved as one group.
While improved speed is an advantage, the possibility of fragmented data is high when a data cluster is used. When the file is saved, especially on systems optimized for larger cluster sizes, the file normally will be smaller than the entire cluster. This normally is not a problem with a small amount of files, but computers that have a large number of files may experience fragmented data. The portions of the cluster that are not used become fragmented and wasted, because they cannot be freed up for other files; this may cause speed problems or reduce the overall amount of computer memory.