SHCC WYSIWYG Article from June 2014

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This article was written by Don VanSyckel, the club president, as a part of "The President's Pen".  This article appeared in the June 2014 WYSIWYG newsletter.

Do You Defrag?

by Don VanSyckel

Do you defrag? Do you even know what that means? It's about your disk drive. For those of you with the new solid state drives you can skip down to the last paragraph. You can think of a disk drive as a number of equal size compartments. There are several different schemes to determine where a file is written so I'll use a generalize example. When the first file is written it goes into the first compartment and if that fills the next compartment is used and another if needed until the entire file is written. When the next file is written the process continues. The interesting part comes when you delete files or add to an existing file. For instance you email inbox exists on the disk and is added to as you receive new mail.

In this example the new portion of your email inbox is written at the end where there are empty compartments. A similar thing happens with the space previously used by files now deleted. As you write a new file or add to an existing one the now unused 'holes' (empty compartments that were previously used and are not surrounded by used compartments) are used. Some of a file goes in one hole. Then the writing process continues with the next hole and the next and the next. As this process goes on for weeks and for months various files get split up into more and more pieces. Regardless of how many pieces a file is split into the amount of space it takes on the disk is the same. What is different is it takes time to position the disk read/write head to access each piece and then find that piece as the disk spins. This is called disk fragmentation.

Image if the data was written to contiguous compartments. To access a file the read/write head needs to be positioned once. If the file is larger than one track, a revolution of the disk, the next track is used. this minimal 'step' is done at minimal time cost. If all your files were contiguous on the disk read and writing would take a minimum amount of time. Windows comes with a defragmenter. This program rearranges the data on the disk so that files are each contained in contiguous compartment on the disk. The length of time it takes the defragmenter to run depends on the speed of your disk and how much data on the disk is fragmented.

If you're running the defragmenter for the first time, I suggest you start it when you go to bed, it can take hours. It is suggested here that you defrag a disk only when you are not using it or when you are using it very lightly. If you defrag the disk on a regular basis, a defrag can complete in a few minutes.

An alternative defragmenter was recently recommended to me. This program named Defraggler is available for download at www.defraggler.com. There is a free version of a full featured version for purchase. Defraggler definitely takes longer to run the first time. Even after defraging with the Windows version, Defraggler definitely goes beyond what the Windows supplied defragmenter does.

When a disk has been defragmented, the read/write head has less movement to do and the access times to read or write files is reduced. The other thing I do to speed up disk access is use Windows disk compression. Most files are 40% to 60% of their uncompressed size. This means that the disk access time is accordingly. So the goal is to read and write files on contiguous pieces on the disk that are half the normal size.

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