Post Description

JkDefrag is based on the standard defragmentation API by Microsoft, a system library that is included in Windows 2000, 2003, XP, Vista, and 2008. Most defragmenters are based on this API, including the free defragmenter that comes with Windows and many commercial defragmenters. Basically all JkDefrag does is send "move this file to that location" commands to the API. JkDefrag does not modify the disk by itself, and is therefore extremely solid.

Defragmentation and optimizing will not only make a harddisk faster, but also lengthen it's life span. The disk will have less work to do and therefore have less wear and tear. Secondly, the sorting optimization strategies (see the "-a" option) will refresh all the magnetic data on your harddisk. However, defragmenting and optimizing is work, so excessive defragmenting and optimizing can actually cause more wear and tear than it prevents. JkDefrag is therefore set for "fast" optimization by default, intended to be used on a daily basis. The other optimizations should only be used occasionally.

Phase 1: Analyze
    JkDefrag has to scan all the files on the disk to determine if they are fragmented and where they are. A second step inside this phase will apply the exclude masks and determine which files are SpaceHogs. 
Phase 2: Defragment
    All fragmented files are defragmented, simply by moving them to the first gap on the disk that is big enough. If there is no gap big enough then the defragmenter will reduce the number of fragments in the file by moving as much of the file as possible into the largest gaps available. 
Phase 3: Optimize

        * On most harddisks the beginning of the harddisk is considerably faster than the end, sometimes by as much as 200 percent! See the link to "HD Tune" in the "See Also" chapter for a nice little free program to measure your disk. The default JkDefrag optimization strategy therefore moves all files to the beginning of the volume. It is intended for daily use and will simply fill gaps with files from above, very quick and with very little data movement.
        * JkDefrag classifies files into 3 zones: directories (zone 1), regular files (zone 2), and SpaceHogs (zone 3). Directories are perhaps the most accessed data on disk, so zone 1 is placed at the beginning of the harddisk. After the directories comes a free area (see below), then zone 2 with regular files, another free area, and then zone 3 with SpaceHogs (less important files that take up a lot of space). The beginning and end of the zones is determined automatically, see the "-f" option.
        * A running computer will create and delete temporary files like there is no tomorrow. If the harddisk were completely optimized then the only place for new temporary files would be behind all the other data. Which is rather slow. So JkDefrag maintains a free space of 1% of the total disk space between zone 1 (directories) and zone 2 (regular files), and between zone 2 and zone 3 (SpaceHogs).
        * Sorting the files on your disk can give you even more speed. There are several sorting strategies to choose from (see the "-a" options). These are all very slow and intended for occasional use only.
        * Windows reserves a percentage of the disk for the MFT (Master File Table), but can place normal files there if the rest of the disk is full. The files will remain there, even when there is enough space again. JkDefrag looks for files in the MFT reserved space and moves them to normal diskspace, making the reserved space available again for the MFT. 

When JkDefrag is running you will see lot's of messages zipping by showing you exactly what is happening. The messages are also stored in the logfile ("JkDefrag.log" or "JkDefragCmd.log") for later inspection. The logfile may also contain warning messages, for example when a file could not be moved. This is normal, no need to worry. Windows has many system files that cannot be moved while Windows is running.