2011-11-25 02:27 AM
I have few questions about using sysstat and about how reliable the readings are.
If we have a filer which has 4 cpus, what reading does the cpu display when using sysstat, is it the avg of all cpu's. And we when we sysstat -m its displays the % reading of all CPU's, but what does the 'any' colums reading mean. I dont thinks its the avg of all cpus'.
Also the disk utlization % reading, how does it compare to the cpu reading, if the disk utlization is high and cpu % reading is normal is that OK. And where does the disk utlization reading come from, is the avg of all disks or the busiest disk.
Also the cache age setting, what values shows there maybe an issue, is that when the age is high or low.
ANy advise on this and also what settings to look out for when using sysstat.
2011-11-25 03:34 AM
This is all in the man pages for the sysstat command:
The CPU column shows the highest CPU utilization between all your CPUs, so it's perfectly normal that it moves to 99% from time to time.
If you use sysstat -m, the ANY colum shows the percentage of time (within the interval) that at least one CPU was busy (i.e. not in the idle task)
Disk Util% is the same as CPU utilization, it shows the disk that has the highest utilization (i.e. if you have a hotspot disk you will continually see high values here)
Cache age is the age of the data that has been recently removed from the cache. It is normally the age of the oldest data item in the read cache, but it can get lower when the system requires memory for other tasks (snapmirror, dedup, etc.) and needs to free some more buffers
hope that helps