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(tool, file system)
/dee-frag(-ment)'/ (Or "defrag") To coalesce files and free space on a file system; to reduce fragmentation.


To reorganize the disk by putting files into contiguous order. Because the operating system stores new data in whatever free space is available, data files become spread out across the disk as they are updated. Large files may be broken into thousands of fragments, causing the read/write head to move back and forth numerous extra times to read the data. A "defragger" or "optimizer program" rewrites all the files and stores them in adjacent sectors.

Windows comes with the DEFRAG.EXE utility, which can be activated by the Run dialog from the Start menu. Other popular defraggers, such as Diskeeper, offer enhanced capabilities.

Users Run the Gamut
Some users are fanatical about defragging their disks on a regular basis. Others rarely do it, if ever. After defragmenting, performance increases are most noticeable on very large databases that had been heavily fragmented. Because today's computers are so fast, users may not notice any increase in speed with routine applications such as word processing and spreadsheets, especially if the files are small.

A Good Habit
Nevertheless, defragmenting disks regularly is good practice because it reduces wear and tear on the drive mechanism. In addition, should the hard disk ever crash and you did not back up important files, data recovery experts will tell you that a defragged disk is much easier to restore.

Before and After
Diskeeper is one of the most popular defraggers on the market. The red in the drive map at the top shows all the fragmented files. After defragmenting, the new drive map was pasted on the bottom for comparison. Diskeeper can be set up to defrag the disk whenever the machine is idle. As soon as the user clicks the mouse or presses a key, the defragging is suspended.
References in periodicals archive ?
Trying to defragment a drive that has multiple partitions or a RAID array doesn't make much sense, either.
Diskeeper(R) 2008 with InvisiTasking(TM) represents the perfect tool to defragment RAID arr+as it does it on the background as fragmentation occurs, thus letting them perform at their peak constantly.
And, the reported also pointed out, that "The decision to defragment the enterprise automatically verses manually will save companies thousands if not millions of dollars.
It can be set to automatically recover and defragment available memory at specific time intervals or to recover memory when the amount of available memory drops below a certain level.
Since IntelliWrite prevents the majority of fragmentation, it not only provides energy savings on file write I/O: it also minimizes the energy overhead of the defragmentation process itself, as there is simply much less to defragment when using Diskeeper.
One new method is to bypass the Windows NT 0/S and the special APIs in order to defragment the MFT online (Microsoft technical authorities consider this approach dangerous), Alternatives include offline defragmentation during rebooting (less convenient, but safe) and the latest approach of Diskeeper 5.
The resources required to defragment large disks have increased disproportionately with the growth in disk size, making a vital process more expensive than need be.
Further, because there can be so much on a partition, it takes a lot longer to defragment the drive--and you may not want to wait while it's being done.
Now we are seldom called regarding a slow PC, and now we no longer attempt to defragment as part of the initial troubleshooting.
Robert Brown, IT Director, M&Q Plastic Products, also stated, "Diskeeper reduced the time needed to analyze and defragment our machines.