As your hard drive saves and deletes files, the hard drive mechanism for the drive will place this information anywhere it can find available free space. If there is not a contiguous amount of disk space to save the file, your drive will fragment the file. Saving a piece here and a piece there. This is transparent to the user, since the file still appears to be one complete item.
Fragmented files can, however, cause a performance loss on your hard drive. Instead of your drive being able to scoop up a requested file in one swoop, it must find all the pieces at various places on the drive. This increases the amount of time needed to read and write files and results in a degradation of performance.
A cure for fragmented files is to optimize your drive. This involves using software (like TechTool Pro) to rearrange all of the file fragments and reassemble them into contiguous areas on the disk. This is done much like the game "Hanoi Towers" is placed. Several files may need to be moved before the target file will have enough free space to be written contiguously. This is repeated many times until all or most of the files are no longer fragmented.
There are two methods to optimize files on a disk. One is to use low-level calls, which rewrites the directory and extents information. This method involves many modifications to the basic file structure of the drive. While this method is fast, it could cause a loss of some or all of your data in the event of a power failure, crash or some other event that interrupts recreation of critical drive files. In most cases, this method also requires the user to boot from another drive or CD if they wish to optimize their system drive.
The other method, employed by TechTool Pro, uses standard file write-copy-delete methods to rearrange the files. While this method is slower than using low-level calls, it is far safer since there is no risk to the data. You can literally unplug your machine during optimization, with no ill-effect to your drive or data. There is also the added benefit that if you wish to optimize your system drive, there is no need to boot from another drive or the TechTool Pro CD.
Test & Functions Descriptions
Files - This option will defragment only files on your hard drive(s).
Disk - This option will optimization files and free space on your hard drive(s).
Controls & Displays
Defragment - Allows you to select which optimization option you want to perform.
Rescan Volumes - This button allows you to update the drive and volume listing in the Volume List display.
• File Defragment Key
Optimized (Yellow)- This area represents the optimized portion on the selected hard drive.
Low Fragments (Orange) - This area represents the low fragments (file is broken up into less than 3 segments) on the selected hard drive.
High Fragments (Red) - This area represents the high fragments (file broken up into three or more segments) on the selected hard drive.
Free Space (Green) - This area represents the available free space remaining on the selected hard drive.
• Disk Defragment Key
Target (Red) - This area represents the target area of where data from the volume will be moved.
Directory (Blue) - This area represents the directory structure on the selected hard drive. The directory contains the Volume Header, Extents File, Catalog File, Attributes File, Startup File and Allocation File. This are is normally found at the top left portion of the disk optimization screen.
Used Space (Yellow) - This area represents the used space on the selected hard drive.
Free Space (Green) - This area represents the available free space on the selected hard drive.
Usage Notes
The optimization feature should be used as a general disk maintenance routine for your Macintosh. In the Standard Interface, the optimization test only performs a file optimization. This is important to know, especially if this test fails.
If the optimization feature fails in the Standard Interface, it is recommended that you allow TechTool Pro 2 to proceed with the optimization of your files. If the optimization routine fails after allowing it to repair, you should go to the Volume Structures panel in the Expert Interface for testing.
At the Volume Structures panel, select all available tests then choose the drive that failed the previous optimization routine. Run the Validate Only option. Running this test will inform you if a volume structure issue exists on the selected hard drive. If a problem does exist, you should backup the data on the drive and perform a Validate & Repair option afterwards in the Volume Structures panel to resolve the issue.
It is also recommended that you perform a Volume Structure test and a File defragmentation prior to running the Disk defragmentation on the drive. This will allow TechTool Pro 2 to optimize more efficiently.
Common Questions
Q: Do I need to run the optimization feature from my TechTool Pro 2 CD every time I want to optimize my hard drive(s)?
A: No. Since TechTool Pro utilizes a file-level optimization routine, there is no need to dismount the target drive; therefore there is no need to boot from the TechTool Pro CD. The optimization feature can be executed locally from the hard drive that you wish to optimize. There is no need to boot from a secondary device or the TechTool Pro 2 CD-ROM to do this routine.
Q: What is the difference between optimizing files and optimizing the disk?
A: File optimization takes all fragmented parts of file and puts them back together. Disk optimization makes the discontiguous free space of the drive contiguous.
Q: Why is there two Red (Target) areas displayed during the disk optimization at the same time?
A: This occurs because the resource and data fork for a file are in two different locations on the drive. TechTool Pro 2 will automatically put these two items together during the disk optimization routine.
Q: When I run the File optimization option, I get a message saying "there isn't enough contiguous free space" on my drive. What does this mean?
A: In order for TechTool Pro 2 to perform file optimization on your hard drive, you must have enough available free space on the drive for TechTool Pro 2 to operate. As a general rule, it is always recommended that you have no less than 10% of free space on your hard drive.
