UNIX System Administration Handbook - Evi Nemeth [443]
Anything with moving parts may need regular lubrication, cleaning, and belt maintenance. Old line printers are prime candidates, as are old tape drives and disk drives (but all disks made within the last five years or so are totally sealed and maintenance free). Listen for squeaks from your older equipment and pamper it accordingly.
On server systems, the part that most frequently fails is the fan and power supply module—especially on PCs, where it is often a single field-replaceable unit (FRU). Periodically check your servers to make sure their main fans are spinning fast and strong. If not, you must usually replace the entire power supply assembly—otherwise, you run the risk of overheating your equipment. Do not try to lubricate the fan itself; this procedure might postpone the inevitable breakdown, but it could also accelerate the problem or cause damage to other components.
A computer in a dusty environment will burn out components much more frequently than one whose environment is relatively clean. Dust clogs filters, dries out lubrication, jams moving parts (fans), and coats components with a layer of dusty “insulation” that reduces their ability to dissipate heat. All of these effects tend to increase operating temperatures. Check and clean dust filters regularly. You may also need to give your systems’ innards an occasional housecleaning in bad environments. (Any environment that features carpeting is likely to be bad.)
Vacuuming is the best way to remove dust, but be sure to keep the motor at least five feet from system components and disks to minimize magnetic field interference. Your machine room should be vacuumed regularly, but make sure this task is performed by people who have been trained to respect proper distances and not harm equipment (office janitorial staff are usually not acceptable candidates for this task).
Tape drives usually require regular cleaning as well. You clean most cassette-type drives by inserting a special cleaning cassette. Other formats may need manual cleaning with Q-Tips and denatured alcohol.
24.7 Environment
Just like humans, computers work better and longer if they’re happy in their environment. Although they don’t care much about having a window with a view, you do need to pay attention to other aspects of their home.
Temperature
The ideal operating temperature for computer equipment is 64° to 68°F (17° to 20°C), with about 45% humidity. Unfortunately, this temperature does not coincide with the ideal operating temperature of a computer user. Ambient temperatures above 80°F (27°C) in the computer room imply about 120°F (49°C) inside machines. Commercial-grade chips have an operational range up to about 120°F, at which point they stop working; beyond about 160°F (71°C), they break.
Humidity
The ideal humidity for most computer hardware is in the range of 40% to 60%. If the humidity is too low, static electricity becomes a problem. If it is too high, condensation can form on the boards, causing shorting and oxidation.
Office cooling
These days, many computers live in people’s offices and must survive on building air conditioning (often turned off at night and on weekends) and overcome an healthy dose of papers and books on cooling vents. When you put a computer in an office, keep in mind that it will steal air conditioning that is intended for humans. Heating, Ventilation, and Air Conditioning (HVAC) engineers are notoriously bad at estimating the actual cooling load for an office with a computer in it. If you are in a role where you can influence cooling capacity, a good rule of thumb is that each human in the room produces 300 BTUH worth of heat, whereas your average office PC produces about 1,100 BTUH. Don’t let the engineers forget to add in solar load for any windows that receive direct sunlight.
Machine room cooling
If you are “lucky” enough to be moving your herd of UNIX servers into one of those fancy raised-floor