Hardware is a common cause of data problems. Power can fail, electronics age, add-in boards can be installed wrong, you can mistype, there are accidents of all kinds, a repair technician can actually cause problems, and magnets you don’t know are there can damage disks.
Your PC is busy writing data to the disk and the lights go out! “Arghhhh!” Is everything OK? Maybe so, maybe not; it’s vital to know for sure if anything was damaged.
Other power problems of a similar nature would include brownouts, voltage spikes, and frequency shifts. All can cause data problems, particularly if they occur when data is being written to disk (data in memory generally does not get corrupted by power problems; it just gets erased if the problems are serious enough).
- Brownout: Lower voltages at electrical outlets. Usually they are caused by an extraordinary drain on the power system. Frequently you will see a brownout during a heat wave when more people than normal have air conditioners on full. Sometimes these power shortages will be “rolling” across the area giving everyone a temporary brownout. Maybe you’ll get yours just as that important file is being written to disk.
- Voltage Spikes: Temporary voltage increases are fairly common. Large motors or circuit breakers in industry can put them on the electrical line. Sudden losses (e.g., a driver hits a power pole) can causes spikes as the circuits balance. An appliance in your home can cause a spike, particularly with older wiring. Lightning can put large spikes on power lines. And, the list goes on. In addition to current backups and integrity information for your software and data files, including a hardware voltage spike protection device between the wall and your computer hardware (don’t forget the printer and monitor) can be very helpful.
- Frequency Shifts: While infrequent, if the line frequency varies from the normal 60 Hertz (or 50 Hertz in some countries), the power supply on the computer can be affected and this, in turn, can reflect back into the computer causing data loss.
Solution: Consider a combined surge protector and uninterruptible power supply.
It’s not magic; as computers age they tend to fail more often. Electronic components are stressed over time as they heat up and cool down. Mechanical components simply wear out. Some of these failures will be dramatic; something will just stop working. Some, however, can be slow and not obvious. Regrettably, it’s not a question of “if”, but “when” in regard to equipment failure.
Solution: Keep an eye on the specials after three to five years.
You can have hardware problems on a perfectly healthy PC if you have devices installed that do not properly share interrupts. Sometimes problems are immediately obvious, other times they are subtle and depend upon certain events to happen at just the wrong time, then suddenly strange things happen! (Software can do this too!)
Solution: Make a really good backup before installing anything (hardware or software) so you can revert the system back to a stable state should something crop up.
(Typos and “OOPS! I didn’t mean to do that!”)
These are an all too frequent cause of data corruption. This commonly happens when you are intending to delete or replace one file but actually get another. By using wild cards, you may experience a really “wild” time. “Hmmm I thought I deleted all the *.BAK files; but they’re still here; something was deleted; what was it? Or was I in the other directory?” Of course if you’re a programmer or if you use sophisticated tools like a sector editor, then your fingers can really get you into trouble!
Another finger fault problem arises with touchpads below the space bar on notebook computers. It’s very easy to brush the touchpad when you are typing away and suddenly find yourself entering characters in a screen location very different from where you were before you touched the pad.
Solution: Be careful and look up now and again to make certain your cursor is where you want it.
Malicious or Careless Damage
Someone may accidentally or deliberately delete or change a file on your PC when you’re not around. If you don’t keep your PC locked in a safe, then this is a risk. Who knows what was changed or deleted? Wouldn’t it be nice to know if anything changed over the weekend? Most of this type of damage is done unintentionally by someone you probably know. This person didn’t mean to cause trouble; they simply didn’t know what they were doing when they used your PC.
Solution: Never run the computer as an administrative user and have guest accounts available for others who use the computer. Keep up-to-date backups as well.
One possible source for computer infections is the Customer Engineer (CE), or repairman. When a CE comes for a service call, they will almost always run a diagnostic program from diskette. It’s very easy for these diskettes to become infected and spread the infection to your computer. Sales representatives showing demonstrations via floppy disks are also possibly spreading viruses. Always check your system after other people have placed their floppy disk into it. (Better yet, if you can, check their disk with up-to-date anti-virus software before anything is run.)
Solution: Insist on testing their disk before use or make certain they’ve used an up-to-date anti-virus before coming to your location.
Computer data is generally stored as a series of magnetic changes on disks. While hard disks are generally safe from most magnetic threats because they are encased within the computer compartment, floppy disks are highly vulnerable to magnets. The obvious threat would be to post a floppy disk to the refrigerator with a magnet; but there are many other, more subtle, threats.
Some of the more subtle sources of magnetism include:
- Computer Monitor. Don’t put floppy disks anywhere near the monitor; it generates a magnetic field. (Generally applies to the older CRT displays.)
- Telephone. When ringing, telephones (particularly older phones with a bell) generate a magnetic field.
- Bottom Desk Drawer. While the desk drawer does not generate a magnetic field, the vacuum cleaner that the maintenance people slide under the desk to clean the floor does.
- Bottom Bookcase Shelf and File Cabinet Drawer. Same comment as the desk drawer just above.
- Pets. Pet fur generates a strong electrostatic charge which, if discharged through a disk, can affect files on the disk. Instead of “The dog ate my homework,” today it could just as easily be: “The cat sat on my homework.” (I once had a student where this exact problem happened; a cat sat on her floppy disk and static wiped out the data on the disk.)
Solution: Stay away from magnets or sources of static of all kinds when working with a computer.
Bottom line: There are tools to assist in recovery from disk problems, but how do you know all the data is OK? These tools do not always recover good copies of the original files. Active action on your part before disaster strikes is your best defense. It’s best to have a good, current backup and, for better protection, a complete up-to-date integrity-check map of everything on your disk.
- There are many different kinds of hardware threats to your data. Some include:
- Power faults
- Equipment incompatibilities
- Accidental or deliberate damage
- The Customer Engineer or friendly salesperson
- Problems with magnets and/or sources of static electricity
- Active action on your part can help you identify problems and, perhaps, head them off early.
|Introduction to Viruses|
|Why do People Write Viruses||Software Threats|