Recomended interval for sar -w

[Karl-Johan Halléni]

I need to run the "sar -w" to monitor the possible swapping during a day. Is there a recomendation of the interval of the readings?

I understand that check every second the whole day may be a little overkill, might have some impact on the performance as well?

Thanx in advance and good luck in the Olympic Games! Sweden only have two brons medals yet:-(

[A. Clay Stephenson · Accepted solution]

Hi:

There is no really good answer other than 'it depends'. A good starting point is 20 minute intervals. That is a reasonable compromise between the number of data points and performance impact. You can then adjust from there. Really the only swapping number to be concerned about is the pageout rate. If you want really good system statistics, MeasureWare is hard to beat.

[Scott_14]

Hello:

you can put this in your cron
0 * * * * /usr/lbin/sa/sa1 1200 3
0 0 * * * /usr/lbin/sa/sa2 -s 00:00 -e 23:45 -i 3600 -A


that way you can get the whole days worth, and can run sar on the file it creates in /var/adm/sa/sa## where the ## is the day of the month it collected.

I know this is more than you wanted, but this is the most popular method I have seen. And you can get other results by running different options on the files.

scott

[Carlos Fernandez Riera]

Sar must not be run for less than 5 seconds.

At a first step you must take metrics 4 or 5 times per hour.

Once you have located when swap incresasses, thencan restrict to minutes or seconds.


See man sa2.