When computers lose power
| Pages | 505-509 |
| Published date | 01 June 1997 |
| DOI | https://doi.org/10.1108/eb045603 |
| Date | 01 June 1997 |
| Author | Howard Falk |
| Subject Matter | Information & knowledge management,Library & information science |
When computers lose power
Howard Falk
You have just entered two pages of carefully-composed material into your word processor when the lights in
your office dim and the computer screen goes dark. A few minutes later, the lights come back on again and
you restart your computer. As it grinds through its start-up procedures you wonder whether it will behave nor-
mally or leave you with a serious repair problem. This time you are lucky and your normal applications are
available. However, when you open your word processor and look at the file you were entering, you find that
your last two pages are missing.
Those two pages were stored in random access memory (RAM) and had not yet been transferred to more
permanent disk storage. When the power failed, all the material stored in RAM simply disappeared, since
RAM memory only works when the computer is powered up.
Even disk storage, which normally retains information even when the computer is turned off, is vulnerable to
power failure. If power is lost when the disk is actively reading or
writing,
the disk mechanism can
'crash'
and
stored information will be destroyed. If the critical file allocation table (FAT) on the disk is damaged, you will
not be able to access any of the files stored on the disk. Although disks damaged in this way can often be
mended,
the job is a delicate one and requires the services of someone who has experience in making this
kind of repair.
Libraries, like most organisations, are vulnerable to electric utility
abnormalities.
When
there is a power black-
out, however brief, the library's computers will lose RAM memory contents and disk-stored material may be
damaged.
Similar problems may result when lights dim and there is a power brownout. These power prob-
lems can be merely annoying but they can also be expensive to repair, and it is possible that valuable infor-
mation stored in computers may be lost.
Surviving power disturbances
Although blackouts and brownouts may be infre-
quent, they do persistently occur. There seems little
future hope of trouble-free power since many fac-
tors,
such as power utility investment in excess
capacity and the vagaries of severe weather condi-
tions,
are unlikely to change. Libraries must there-
fore take appropriate measures to protect their com-
puters from power disturbances.
The 'uninterruptable' power supply (UPS) is an ele-
gant solution to blackout and brownout problems.
Each UPS contains its own power source that is
independent of power utility supply lines. When a
blackout or brownout occurs, the UPS automatically
produces its own power to substitute for the lost
util-
ity power.
In addition to lost or inadequate power, momentary
excessive power can also be a problem. Excessive
power to computers may be caused by a surge due
to a lightning strike, or by spikes or surges in utility-
supplied power. Power surges can damage comput-
er components, shortening their useful lives or
requiring immediate component replacement. Most
UPS units include the capability to handle lightning
and utility supply surges. For equipment not
con-
nected to a UPS, inexpensive surge suppression
devices are available. These devices are embodied
in the familiar power supply strip that plugs into a
util-
ity electrical outlet, and offers multiple sockets into
which computer equipment can be plugged.
Do you need a UPS?
If you have never had a disastrous experience with
damage due to loss of utility power, you probably feel
no urgency about obtaining power backup equip-
ment. In that case, you might well talk to colleagues
who have had less-favourable experiences and try to
get a balanced viewpoint on the need for UPS equip-
ment. Utility power disturbances occur rather infre-
quently but they do seem inevitably to take place.
The real question is not whether your library will
experience a blackout or brownout (partial loss of
power) but whether the probable consequences of
such events merit an investment in UPS equipment.
A simple UPS, capable of protecting a desktop com-
puter system, can be purchased for about $120.
Envision what you might encounter if the disk stor-
age in your computer suddenly became unavailable
and you couldn't start the computer or access any-
thing,
not even the operating system itself. Try to
evaluate in your own mind the cost of getting the
computer into operation again, plus the cost in time
and effort to reconstruct those lost files that could be
retrieved,
plus the cost of losing other files entirely. If
HARDWARE
CORNER
The Electronic Library, Vol. 15, No. 6, December 1997 505
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