Storage

Start with the usual suspects when diagnosing floppy-disk problems

You make it a point to stay on the cutting edge of IT, so it's only fitting that your next support call is for a cantankerous old floppy drive. You're as far from the cutting edge as you can get, but can you still find the fix?


The floppy drive is the one component in the modern PC that has the dubious distinction of remaining basically unchanged since the original IBM PC. Of course, disk types and capacities have changed, but the cabling, controller, and CMOS settings are pretty much the same as they were in the beginning. Even with the advent of Zip drives, CD-RW drives, and LS-120 Super Floppy drives, most modern PCs still have a standard 3.5-inch floppy drive.

Because these drives are so common, it's highly likely you will be called upon to troubleshoot at least one during your career in IT support. To prepare you for this inevitable challenge, I'll begin my series on troubleshooting floppy drives by focusing on diagnosing failed disks and ways to prevent your OS from hiding a drive problem.

It's most likely the disk
When a floppy disk suddenly begins experiencing problems, the disk itself should be at the top of your list of suspects. Compared to other forms of media, floppy disks are especially frail. They can be ruined by anything ranging from dust to magnetic interference. The recordable surface of a floppy disk is similar to the material used in cassette tapes. It’s designed to store a magnetic flux. As you write data to a floppy disk, the drive’s write head either supplies or removes a magnetic field from each sector on the disk. The disk is designed to retain this magnetic pattern so that it may be reread at a later time. Occasionally, magnetic interference will “reset” the magnetic field on a disk, rendering the disk unreadable. It’s also not at all uncommon for dust to prevent the drive heads from reading the disk or for a disk to simply lose its magnetic field for no apparent reason. To put it bluntly, floppy disks are not very reliable.

Therefore, when you begin having trouble, the first step in diagnosing the problem is to test the disk in another computer. If neither computer can read a particular disk, then the disk is the problem. If, on the other hand, another computer can read the disk, but yours can’t, then the problem is obviously the floppy drive and not the disk.

Watch out for the OS roadblock
You’ve got to be careful when diagnosing floppy-disk problems, because sometimes your operating system (OS) will prevent you from seeing the problem for what it really is. For example, suppose that you need to give a file to someone else by way of a floppy disk. You write the file to the disk and then look at the disk’s directory to verify that the file exists. You then give the disk to your friend, who calls you later to tell you that the disk is blank. You create the disk again, this time being very careful to verify the existence of the file. You might even go so far as to open the file directly off of the floppy disk. You give the new disk to your friend, and your friend tells you that the second disk is also blank. What’s going on?

I’ve seen this situation occur countless times in real life. The first couple of times I saw it happen, I assumed that the person who received the disk was having floppy-drive problems, such as dirty drive heads. However, when I tried reading the disk in the drive that originally created it, the disk was blank. How could this be?

The answer is that the OS’s disk caching was preventing us from seeing the real problem, which was that the drive’s write head was screwed up. The computer thought that the drive had written to the disk, but in actuality, the disk was blank. When I looked at the contents of the directory or opened the file that was on the disk, the computer was reading the disk cache rather than the disk itself. Therefore, it appeared as though data had been written to the disk, but all the while, the disk was blank.

It's all in the cache
The easiest way to diagnose a problem like this is to write the data to the disk and then eject and reinsert the disk. Because the computer can tell that the disk was ejected and another disk was inserted, the disk cache for the floppy drive will be cleared. This means that the next time that you read the disk, you’ll be reading from the disk itself and not from the cache, because the cache is empty. Keep in mind, though, that once you’ve read something from the disk, whatever you read will most likely be copied to the cache and will be read from the cache until the next time you eject the disk.

Share your floppy fixes
If you've recently resolved a tough floppy-drive problem, we want to know about it. Do your workstations even have floppy drives? Will floppy drives soon be a PC relic like the 5.25-inch floppies? Post a comment to this article and share your thoughts.

 

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