Cosc 4750 Maintenance & Analysis

Maintenance Contracts Annual cost of 10%-12% of component’s list price. On-site maintenance –usually within hours a vendor’s tech will come out and fix the problem. “parts & care” –Vendor will send you a replacement for the “broken” part, you put it in and send the old part back.

Warranties –usually good for 1 to 3 years –normally a “parts & care” contract –Some company offering on-site service as well

Board Handling lore static electricity –electronics are sensitive to static shock –Should use a grounding strap on the wrist when working with electronics Reseating boards –Sometimes, the a board works it way loose or loses contact, so you reseat a board. –Also, wiggling a board will help as well. See demo in class

Monitors –Do NOT attempt to fix them yourself. –Holds an electric charge that can seriously hurt or kill you.

Preventive Maintenance Computers should cleaned regularly. –Normally, mid spring –Either vacuumed or blown clean –boards reseated or wiggled –Don’t lubricate fans or parts. Simply replace them.

Environment Temperature –between 60 to 70 o F –Above 80 ambient temperatures means about 120 inside the computer. –Also kept computers out of direct sunlight Humidity –about 45% is best A/C can help to kept both in check. Beware of your power drain by computers and UPS. You can cause local low power to your computers. –one study estimated that 13% of electrical power in use is consumed by computers.

Sys Admin Tool Box

Performance and Analysis UNIX will give each process an illusion of infinite resources When UNIX runs out, it will work hard to maintain the illusion, but the system usually comes to a halt.

Collect and review data on the system –What is the average CPU usage and memory usage. –When a problem happens you can find out why more easily. –When adding a new application, check with the vendor for average cpu and memory usage. Can you machine handle it?

Improving performance Turn off unused or un-necessary programs and daemons Adding more memory is a good idea. Attempt to correct usage problems –Have huge processes run over night –balance the system load with another machine if possible.

Reorganize/organize hard drives for better use –Move hard drives around, put them on separate controllers. Monitor network usage –with netstat or other programs –If you network traffic is above 80%, you are in trouble.

Analyzing CPU usage vmstat and/or sar –lists obtain summary information about cpu usage. –sar –u 5 5 lists percentage of cpu time on user code, kernel code, and idle. –vmstat shows similar information and page faults and memory information.

uptime –shows system up time and load averages for 1, 5, and 10 minutes (or 5,10, and 15 minutes) –A lot average double the number of CPU’s in the computer is when the system will begin to fail.

memory usage swap (sun, sgi), swapinfo (hp-UX), swapon –s (redhat), pstat –s (freeBSD) –display swap space, free, total, and used. vmstat 5 5 –displays processes: running, blocked I/O, and swapped out.

Disk I/O iostat 5 5 –displays tty activity, each harddrive, nfs, and cpu activity. iostat –D 5 5 –display percentage of use

Redhat Performance data procinfo provides a summary of system performance information in a more readable form. procinfo –f info and updates every 5 seconds.

quick fixes use top or ps to find runaway processes or “power users”, when the system is very slow. Can use a command called limit –limit memoryuse 32m –All subsequent commands can only use 32m of physical memory.

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