Cosc 4750

Maintenance & Analysis

Maintenance Contracts

• Annual cost of 10%-12% of component’s list price.

• On-site maintenance– usually within 24-48 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 70oF– 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.

QA&