|Performance Analysis and Tuning Simplified|
|News from Tech Support - The Linux FAQ
Here's the FAQ section from the manual. These questions make up 80 percent of our support calls.
Frequently asked questions (FAQ):
Q1: What versions of Linux does SarCheck support?
A1: We haven't tried all kernels or distributions, but we support most systems running Linux kernels 2.2 through 2.6.
Q2: Should I implement recommendations that only show up occasionally?
A2: Feel free to try, but first implement the regularly occurring recommendations, since those will address the most frequently occurring problems. If SarCheck occasionally recommends increasing the amount of memory, you should certainly try it. On systems with some extra memory, SarCheck will be able to make additional recommendations that could not be made on systems where memory is "tight".
Q3: Every time I make changes based on SarCheck's recommendations, it makes more recommendations. Why doesn't it just figure out the correct values for all the parameters?
A3: That's not how real performance tuning works. There are no "correct" values because tuning is a series of compromises between various system resources. Performance tuning involves a certain degree of trial and error, and gradual change is the only way to do it.
Q4: When I try to run sarcheck, I get the message "sarcheck: not found". What's wrong?
A4: Check the following:
Q5: Why did SarCheck stop producing reports?
A5: Usually this is because the software has expired. Run '/opt/sarcheck/bin/analyze' and look for the expiration date at the bottom of the usage text. If you've licensed SarCheck and the expiration date doesn't make sense to you, run 'analyze -s' and send us the output.
Q6: How do I collect data at 10 minute intervals over a 24 hour period?
A6: The crontab entries should look like this:
0,10,20,30,40,50 * * * * /opt/sarcheck/bin/prst1
Q7: How do I collect data every 20 minutes from 08:00 to 18:00?
A7:. The crontab entries should look like this:
0,20,40 8-17 * * * /opt/sarcheck/bin/prst1
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