A few weeks ago I wrote a column encouraging users to upgrade to DOS 6, the latest version of Microsoft's Disk Operating System.
If you haven't upgraded, consider holding off for a while. Since that column was written, I've talked with a handful of users who have had serious problems with DOS 6, particularly with hard disk crashes using DoubleSpace, the new file compression utility that vastly increases the capacity of the user's hard disk. Similar problems have been reported across the country.
While Microsoft insists DOS 6 and DoubleSpace are sound, the litany of complaints in messages on Microsoft's DOS forum on the Compuserve Information Service is pretty grim.
More troubling is a test conducted on 50 computers by InfoWorld, an influential weekly trade magazine. InfoWorld found that half the computers developed problems with missing sectors, cross-linked files, unusable compressed files and even corrupted executable programs while running the magazine's standard tests on drives compressed by DOS 6.
How serious the problem is remains to be seen. Microsoft spokesmen say InfoWorld's tests were flawed and argue that the volume of complaints is the result of an unusually high number of DOS 6 packages sold -- more than 3,000,000 in just a few weeks.
Complicating this release is the nature of the PC marketplace. Once a hardware monolith dominated by slavish devotion to IBM's architecture, the PC world has become fragmented by manufacturers offering an incredible variety of motherboard, video, disk drive and controller designs. It's impossible to test any new software with all of them. If even a tiny fraction of those installations go bad, it's enough to create a small army of irate users.
Microsoft also notes in its technical support forums that the installation of its DoubleSpace compression program gives a hard disk a lot more exercise than it normally gets. If a drive is marginal or has previously undetected flaws, "DoubleSpace may bring those problems to light," as one Microsoft support person delicately put it.
The company's DOS 6 problem seems odd in light of its salutary experience with DOS 5. After years of buggy releases that had to be fixed after the fact, Microsoft tested DOS 5.0 exhaustively. It proved so bug-free that many users who normally would have been wary of a new DOS release were lulled into a false sense of security.
Microsoft said it tested DOS 6 even more thoroughly.
Certainly, buyers trusted Microsoft when DOS 6 hit the store shelves. Some were so trusting that they never took the simplest precaution of all -- backing up their hard disks before they installed DOS 6 and compressed their drives. When their hard disks crashed, they were out of luck.
To its credit, Microsoft urges users to back up their drives before installing DOS and its DoubleSpace compression software. But many novices have no idea how to go about it. Even if they do, hard disk drives that average well over 100 megabytes today make backups to floppy disks so awkward and time consuming that few users are willing to take the trouble.
(Lesson: if you're storing a lot of critical information that you can't afford to lose, get a tape backup unit. It's worth the money.)
There are a couple of other trouble spots with DOS 6, although none so serious as the disk problem. One is the new MemMaker program, which figures out the best way to load memory resident programs, network software and device drivers above the 640K memory block that DOS uses for normal programs.
MemMaker works its magic by modifying the system configuration and auto-executing batch files that DOS loads HTC when it starts up. This is a black art. Sometimes MemMaker is too aggressive in packing upper memory. As a result, there can be conflicts that result in system crashes. These usually occur on start-up, and DOS 6 now allows you to bypass the normal start-up files with a function key to make manual adjustments.
SmartDrive, the disk caching utility, works well but the very nature of the product may cause grief in rare instances. SmartDrive speeds things up by caching data read from the disk drive in memory. More problematically, SmartDrive also caches disk writes. When a program writes data to the disk , SmartDrive may actually hold onto the data for a few seconds until the central microprocessor isn't busy. You may not notice it at all.
But from time to time, when I've saved a file and exited quickly from a program, I've seen the disk drive light flashing for several seconds after the program that wrote the data stopped running.
The danger here is that something nasty, such as a power failure, could happen during the delayed write. You think your data has been saved, but it isn't.
Power failures aren't always the result of sinister forces. If you finish a session with your PC, tell your software to save your data and then flick the power switch immediately, you could produce the same problem.
(Lesson: If you detect any problems along this line, disable write caching. If you are caching disk writes, don't turn the computer off while a program is running. Exit the program, return to DOS and and wait a few seconds to make sure the disk drive isn't still writing before you flick the switch.)
While I've had no problems with DOS 6 on my computer, I'm now being more careful about backing up important files. You should, too. If I were still using an older version of DOS that has proven stable, I'd wait a while to find out whether the problems with DOS 6 are real or just the result of random hardware and software incompatibilities.
Michael J. Himowitz is a columnist for The Baltimore Sun.