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Windows tips: ScanDisk is supposed to, well, scan your disk. And it does that quite well. But after it scans your disk you'd think it would know what to do with the information it gathers. Guess again!
  technofile
Al Fasoldt's reviews and commentaries, continuously available online since 1983

The silly questions asked by ScanDisk


By Al Fasoldt
   Copyright © 1998, Al Fasoldt

   You gotta be kidding.
   That's my reaction when ScanDisk, the Windows disk utility, stops its disk checking at bootup and asks me what I want to do with the junk it's found on my hard drive.
   As if I knew!
   I'm not talking about the "other" ScanDisk, the one you can run in Windows. You get to it in the Start Menu (Programs, then Accessories, then System Tools) or by right clicking a drive icon and choosing Properties. That version of ScanDisk has all sorts of options. You can set them ahead of time and let it, well, let it scan the disk. (Pardon me, but I've seldom seen a more descriptive name for a utility.)
   No, the ScanDisk I'm referring to is the one that lurks behind later versions of Windows, ready to play nanny if your hard drive starts to misbehave each time you boot the PC. This version of ScanDisk -- SCANDISK.EXE -- is the DOS version. (You probably didn't even know there was a DOS version of ScanDisk. Whenever Windows is active and you run ScanDisk, even by specifying "scandisk.exe" in the Run line of the Start Menu, Windows pulls a fast switch and pops up SCANDSKW.EXE as soon as the DOS version starts to run. When you run ScanDisk the normal way in Windows, from the Start Menu or from the Properties sheet of a drive, Windows chooses "scandskw.exe" for you.)
   The DOS version of ScanDisk has two missions in life. The first occurs in the early stages of the Windows setup, when you install Windows. Before it can decide whether to continue with the installation, Windows runs the DOS version of ScanDisk to check your hard drive for errors. (Obviously, it can't run the Windows version because Windows hasn't been installed yet.) The second mission is to spring into action at bootup, when only DOS is running, to recheck your drive if Windows thinks there is a problem. (No, Windows doesn't actually "think," but no one has ever come up with a shorter way of describing the process by which a software program makes such determinations.)
   And how does Windows figure out that your drive might have a problem? You don't want to know. I mean you do want to know, but you won't believe what you know when you find out. Windows is really dumb on this one: It looks at its record-keeping and tries to find out if you were a good citizen and shut down Windows properly the last time you were using your PC. If you were a Bad Guy, Windows automatically assumes that something might be wrong with the hard drive. And so it stops loading, wakes up ScanDisk for DOS and lets the disk utility do its thing.
   Clear so far? I hope so, because the next part is a candidate for an award from the Society for the Preservation of Silliness. That's because ScanDisk for DOS is very smart -- after all, it's trained to ferret out file and disk problems, right? -- but when it finds something wrong, guess what it does? It asks you what do to! Mind you, ScanDisk doesn't show you a list of all the bits and bytes and the linkages between them that might have gone wrong; it just says "Hey, pal, um, I just found this, um, bunch of stuff that, well, seems to be, um, not quite right on your hard drive, and, um, well, whatchawannadowithit?" (That's my translation, of course. But if you've dealt with ScanDisk for DOS, you know I've got the spiel down to a science.)
   ScanDisk is asking you to decide how it should deal with problems. ScanDisk was designed to know how to spot and correct many different problems on a disk, but humans were designed to do something else -- play Doom, maybe, or get the report done in time. The difficulty in knowing how to respond to the questions ScanDisk asks is just that -- we never know how to respond, because we don't have the information about the problem that ScanDisk has. (And ScanDisk isn't telling -- not in any detail, anyway.) Sometimes ScanDisk will suggest that the bad data it found can safely be deleted, and sometimes ScanDisk will show you an ugly, scary message about files that could be damaged. And, always, always, ScanDisk asks if you want to make an Undo file. (It even makes a "Yes" response the default, so you'll get a guilty conscience if you choose "No.")
   Fiddlesticks. What are you going to Undo? If the files are program files, and they're actually damaged, they're already damaged when ScanDisk finds them, so telling ScanDisk to make an Undo file will just give you the option of putting bad files back where they came from. They'll be just as bad after an Undo operation as they were before. Programs won't run if the files that hold them are damaged in even the slightest way.
   If the files are texts, you might be able to make sense out of the damaged versions. But how would you go about doing that? Pulling them into a text editor probably would show pieces of texts. If you really enjoy spending hours and hours trying to find missing paragraphs, go ahead and make an Undo.
   The rational answers to ScanDisk's silly questions are to delete the junk it finds and to skip the Undo file. There are two very good reasons why:
    1. In nearly every case, the junk that ScanDisk finds is just that -- junk. The bad files are nearly always left as orphans when Windows or a Windows program shut down improperly, and usually the files in question are copies of good files. (The File Allocation Table keeps track of where files start and end on the disk, but it will lose track if something dumb happens. Windows always knows how to handle simple problems with the FAT: It checks one FAT table against a backup copy, and uses the one that seems more accurate. It nearly always guesses right. So when orphan files show up in ScanDisk's check, you can nearly always assume that they're just miscreants that a corrupted File Allocation Table created. And you can safely tell ScanDisk to delete them.
    2. You always have your backups. You do have backups, right? I won't preach at you this time. But I'll point out that not having backups is like not having car insurance. You will bang into somebody else's car sometime, and you will find your hard drive grinding sugar one day when you come home from work. Start making backups.

   A brief point at the close: The problems that ScanDisk reports can happen to any PC. They don't mean something is wrong. Hard drives get messed up in little ways all the time. When ScanDisk pops up and starts rummaging through your drive, just pour another cup of coffee and give it a few minutes to do its thing.