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Unit 13: Understanding the Need of Security Measures

13.3 Threats to Hardware Notes

Hardware problems are all too common. We all know that when a PC or disk gets old, it might
start acting erratically and damage some data before it totally dies. Unfortunately, hardware
errors frequently damage data on even young PCs and disks.
Here are some examples.

13.3.1 Power Faults

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.
13.3.2 Incompatibilities
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.

13.3.3 Finger Faults
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!

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