Number 199 - December 1999

Computer Maintenance - Part 3 ScanDisk keeps your computer clean
by Jennifer Fulton http://www.ivillage.com/click/experts/computingcoach/archive/
The system that Windows uses to manage your files is based on an old DOS system called FAT, or file allocation table, and to put it mildly, FAT is a big slob. When the FAT file system goes about deleting a file for you, it does a pretty silly job of it, leaving half-bits of old deleted files lying around like partygoers at an all-night shindig. You see, first of all, when you ask Windows to delete a file, it just moves the thing into the Recycle Bin and doesn't actually delete it at all. But then when you empty the Recycle Bin and tell Windows, 'Gee whiz, I told you to take out that garbage days ago,' it just tells the FAT system to get rid of the file -- which it doesn't actually do. Instead, the clever old FAT system just erases all references to the file in its file listing and marks the space as `available for rent.' The next time you save a file to disk, FAT scans the disk for available spots and picks one (or two, or three, or a dozen, depending on the size of the file). FAT may choose one of the recently vacated spots and copy your new file there, overwriting the data that had been there before.     Parts of your hard disk never become available, even though they contain only little lost bits of old, junky files you never wanted to keep. Little File Lost     All well and good, you might say. FAT may not actually erase the data, but it covers it up with other data, so who cares? Well, in a perfect world, I guess no one would, but in the world of Windows, things are far from perfect. Sometimes when you empty a file from the Recycle Bin (effectively deleting it), FAT will erase the reference to the file but won't mark all of the spaces the file was using as available. The result is that parts of your hard disk never become available, and yet they contain only little lost bits of old, junky files you never wanted to keep. By the way, these lost bits of not-quite-deleted-files are called 'lost clusters' or 'lost chains.'     Luckily for you, although Microsoft can't seem to design an operating system that actually deletes the files you tell it to remove, it can at least design a useful utility to help you fix the problem, and that utility is called ScanDisk. ScanDisk basically goes through your hard disk looking for lost clusters and fixing	them, thus freeing up some disk space that might have otherwise been marked as occupied, even though it contained junk. Crash-Crazy?     To be absolutely fair, if your hard disk has a lot of little lost clusters or chains, it is not all Windows' fault. If you have ever exited a program by just turning off the computer, or shutting of the power switch, then FAT probably didn't have enough warning to put your files away correctly. You may have also turned off the computer in frustration when everything suddenly froze up, which might be some of Windows' fault. In any case, Windows can't be sure that everything's okay when you shut down without following the proper procedure, so Windows will run ScanDisk for you automatically when you power up again. You should let it do that; however, you may want to watch what it is doing, because it will assume that you want it to 'fix' any problem it finds, even if the problem isn't really a problem and is completely unrelated to the reason your computer crashed in the first place. Running ScanDisk     Instead of waiting for a crash and letting Windows start ScanDisk for you, you can run ScanDisk yourself (which you should probably do, about once a month or so). In fact, running ScanDisk under Windows 95 or Windows 98 is a fairly simple and painless process. Just click the Start button and choose Programs>Accessories>System Tools>ScanDisk. Under Type of test, choose Standard. The other option, Thorough, tests the hard disk itself, making some rather tremendous noises as ScanDisk sends the read/write head flying in all directions. This is a good test to try if you think your hard disk is failing, but you don't have to do it to fix some lost clusters. Click the option Automatically fix errors, then click Start to begin. For the fastest results, don't run any programs while ScanDisk is doing its thing. When it's done, it'll say so, displaying a list of the things it found and fixed. Click Close, and you can go back to doing whatever you were doing before.     Stay tuned! Next month, in our never-ending quest to optimize Windows, I'll talk about how to clean up (i.e. untangle) the system registry.
Number 199 - December 1999