Keeping a Hard Disk Problem-Free
The hard disk is the most important component of a business personal computer. It lets you store vast amounts of data and get access to it quickly.
Unfortunately, the hard disk also is the most trouble-prone piece of a computer. Many service technicians say it is not a question of whether, but when, a hard disk will fail.
Until now, copying data to floppy disks or tape drives has been the only protection against the disaster of a hard-disk failure.
Steve Gibson is intent on changing that with a new, $59 disk utility program he has written called SpinRite. After testing it, I am convinced that it is a must-have product for most users of IBM or compatible PCs with hard disks. The only exceptions are those unfortunate souls with computers on which the product will not work, which I’ll mention later.
(If Gibson’s name seems familiar, you may be a reader of his Tech Talk column in InfoWorld, which is just one of the many computer-related ventures this self-taught techie pursues.) To understand what SpinRite does and why it took Gibson a year to write it, I’ll have to get a little technical.
A hard disk, which is hidden inside the computer enclosed in a sealed metal case, is an assembly of one or more round metal disks onto which programs and data are recorded by magnetic heads, somewhat like a tape recorder does with a tape cassette. A floppy disk drive works essentially the same way, except that the disks are made of plastic and are routinely inserted and taken out of the computer. They also store much less data and work at a slower speed.
Rings of Data
The advantage that a disk has over a tape cassette is that a recording head can reach any spot on the rapidly spinning disk within milliseconds. Data stored on a tape can be accessed only when the tape moves past the head. Hard disks typically have about 300 or 600 concentric rings of data, called “tracks” or “cylinders.” The tracks are usually subdivided into 17 sectors, each with its own address number recorded magnetically on the disk at its location, much the way many neighborhoods have house addresses painted on the curbs.
The same thing happens to those magnetic addresses as happens to the ones painted on curbs--they fade over time until the computer can no longer read them and the hard disk fails.
What SpinRite--and only SpinRite--does is magnetically repaint the addresses on the hard disk without disturbing the data residing at that location. In technical terms, it is called low-level formatting. Until SpinRite came along, low-level formatting usually could be done only by service technicians and it permanently erased all the data on the disk in the process.
As SpinRite works, it also thoroughly tests the surface of the hard disk for flaws. It writes and reads test data 84 times at each byte the disk can hold. When flaws that cannot reliably hold data are found, they are stripped of their addresses and permanently locked so that they cannot be used.
SpinRite performs another vital function. It tests how fast your computer can retrieve data from the disk and whether it could be faster if the addresses were arranged differently.
The disk spins at a constant speed, usually 3,600 revolutions per minute. When the computer retrieves data, it has to process the information to make sense of it and display something on your screen or send something to the printer. That takes a few milliseconds, during which time the disk spins.
By the time the computer is ready to read the data at the next storage address, it is ideal if the disk turns to that location at just that moment. If the address spins past just an instant too early, the computer has to wait for the disk to make another revolution before it can get at the data at that address. The trick is to space out the addresses so the timing works out smoothly.
The spacing of the addresses is called the interleave factor, and it is given in numbers such as 1:2, 1:3, 1:4 etc. The closer the two numbers in the interleave factor, the faster the computer must be to efficiently use the disk. SpinRite can respace the numbers by low-level formatting the hard disk with a different interleave factor. The results can be startling. SpinRite discovered that the 72-megabyte drive on my PC-AT clone computer had an interleave of 1:3, but the machine was fast enough to use a 1:2 factor. As a result, my computer now transfers data at 261,000 bytes per second instead of 174,000. The increased speed is quite noticeable.
On my wife’s much modified IBM PC, SpinRite made an even more startling improvement. The IBM’s two 20-megabyte hard disks had a 1:3 interleave, but the computer was too slow to read data continuously at that rate. SpinRite recommended 1:4 as the optimum factor, spacing those addresses a little farther apart. The result was an improvement from transferring 30,000 bytes per second to 130,000 bytes per second. A third computer, an IBM XT, had disks perfectly matched to its capabilities at a 1:3 interleave, SpinRite concluded.
Gibson believes that tuning up a hard disk with SpinRite every two or three months will keep it running error-free indefinitely.
A spokesman for Seagate Technology, the largest maker of personal computer hard disks, said the company has not yet tested SpinRite and thus has no comment on its effectiveness.
Using SpinRite is quite easy, but you have to follow the instructions exactly. It isn’t fast. My 72-megabyte hard disk is divided into three units called partitions, each of which took about 3 1/2 hours for SpinRite to reformat. My wife’s slower PC required about 6 1/2 hours for each of its drives. You can let the program run overnight with no harm.
One thing SpinRite does not do is “optimize” your files by shuffling them so that data for each is stored in contiguously numbered sectors on the disk. If you change the contents of a spreadsheet or a document or add to a database frequently, the new material tends to be stored on your disk some distance away from the earlier recorded portions of the file and it takes the computer a few extra milliseconds to find it. Performance can noticeably suffer after a while.
A number of disk utility programs do optimization. Gibson recommends them and said it makes no difference whether you run such programs before or after you run SpinRite. The manual and an up-to-the-minute report stored on the program disk explain which combinations of hard disks and disk controller cards are incompatible with SpinRite.
Among the incompatible models are all models of HardCard disks, some systems that use a special technology called “RLL” to store 50% more data on a disk and disks with individual partitions greater than 32-megabytes, such as is possible on Compaq computers with Compaq’s version of MS-DOS 3.3.
If you’ve got a hard disk and a fairly standard PC or compatible, regardless of whether it is a slow 8088-chip machine or a speedy 80386-chip unit, SpinRite may well be the best $59 investment you can make in the integrity of your system.
Computer File welcomes readers’ comments but regrets that the author cannot respond individually to letters. Write to Richard O’Reilly, Computer File, Los Angeles Times, Times Mirror Square, Los Angeles, Calif. 90053.
THE SPECS: SPINRITE
Features: SpinRite is a disk utility program intended to prevent hard disk failures. It restores low-level formatting of hard disk, optionally changes interleave factor to speed data access rate if required, tests hard disk for flaws, locks out bad sectors and restores damaged files.
Requirements: IBM or compatible computer with hard disk running PC-DOS or MS-DOS. Works with most, but not all, hard disks. For instance, SpinRite is incompatible with Awesome I/O cards, Priam hard disks and Plus Development HardCard products.
Publisher: Gibson Research Corp., 22991 La Cadena, Laguna Hills, Calif. 92653. (714) 830-2200. Suggested retail price is $59.
