WHAT IS DEFRAGMENTATION ?

what-is-defragmentation ?
-External fragmentation ?
-Internal fragmentation ?

Defragmentation:

Defragmentation is one of the best ways to increase system performance. Disk fragmentation means the storage of data is on physical disk in non contiguous locations and scattered through on the disk. The inability of the physical medium to provide contiguous storage is called as fragmented storage. The inability of storage controller causes two types of disk fragmentation, external and data fragmentation.

External fragmentation:

When the system turns to store a file in the physical location, the physical location may not have enough contiguous space to store that file. In that case the file is stored in non contiguous location. Sometimes when users delete files from the disk it may cause a free space in between files. Such fragmentation is referred to as external fragmentation.

Internal fragmentation :

Internal fragmentation occurs frequently due to some type of failure of the file system store files in-between the storing process. This mostly happens while we cancel the copying of large files during. The file may be left undeleted but occupies more memory than the copied content. This is not considered a major problem but occupies unnecessary space.

Into our Hard Disk :

Let’s say for a sample that we are going to store a file of 5 MB. This file may be located anywhere because the sample disk is using 2048 byte clusters, so totally 2,560 clusters are needed. So these clusters may be on different platters and tracks of the disk. Our computer is made of electronic devices which can deliver responses at the speed of electrons, but our hard disk is just a mechanical device where it consumes time to move its head from one place to another. So this seeking time increases if the file is scattered on the disk and slows our system performance.

We cannot force our system to store files in a contiguous location. But we can rearrange the files to contiguous location. This type of rearranging a file scattered as clusters into consecutive locations is simply called as Defragmentation. Because when a file is rearranged in consecutive locations the head movement is decreased by less seeking between platters and tracks.

Tools:

In windows, two file systems are most commonly used. They are FAT32 and NTFS. Windows 98 supports the FAT file system and the defragment tool build-in with the OS gives good performance. The other third-party tools are JKdefrag, smartDefrag, ultraDefrag; speeDefrag can also defragment the disk. But windows 9x build-in defragmenter is often the best to use.

Windows NT version includes a newer file system called NTFS. The superiority of NTFS disk management capability causes less fragmentation. In earlier releases of NT versions they didn’t include any defragmenter. But the truth is the complexity of file management in NTFS is very much cause for different ways of fragmentation. Since FAT uses simple cluster based storage the Defragmentation is simple and easy to defragment it. In NTFS system the storing of file cause less fragmentation but the addition and removal of data causes more fragmentation. The NTFS uses a MFT (Master File Table) for keep track of file storage. The addition or removal of data from file causes the MFT to grow and causes fragmentation which reduces the performance further.

For Windows NT the popular utility called diskeeper by Executive Software is the best tool in my opinion to defragment the disk. On its wisdom, Microsoft licensed diskeeper and includes it in windows 2000. But the version included is less capable and slower than the full version of the diskeeper. So it is best to use the Diskeeper full version from Executive software to increases the performance of the system. The other third-party tools are Norton Utilities for NT, Perfect Disk 2000, O&O Defragmentation, and VoptNT.