System Perfomance

[nolim073]

Hello Everyone,
Sorry for a very vague question.
I get regular complaints stating that the server is too slow.
Can any one list commands with useful options to gater server performance statics.
(eg i knew that iostat -En proviede good informatin about disks but never knew that iostat -xcn gave much better informatin about disk runtime statics )
Can any one help me with vmstat and other performance gathering commands. I am intrested in paging info, swap info and network informatin ( please adding other things too)

 

[Annihilannic]

Perhaps the most useful is sar because it records information over time. Try typing sar on its own to see if it is already recording performance statistics on your system. If not, enable it by uncommenting the sa1 and sa2 lines in the 'sys' user's crontab.

See the man page for the many options available.

Annihilannic.

 

[marrow]

vmstat will highlight your available CPU
how much memory is spare, how much swap space
high scan rates = low memory,
run queues w = swapped processes - high number of swaps means shortage of physical memory
r = run queue indicates jobs queuing - if 2 x number of processors could mean insufficient CPU power in the system

b = processes blocked waiting for disk; high block rate indicates need for more memory or faster disks/controllers.

prtstat -a lists highest cpu appliactions
prstat -s size highest memory applications

try these for a start

 

[SamBones]

To enable sar data collection, you also need to uncomment some lines in [tt]/etc/init.d/perf[/tt]. If not, the data collection stops if the system if rebooted (just for the remainder of that day).

 

[Annihilannic]

I had completely forgotten about that Sam; I think you only miss the first data poll though if you don't have that enabled, not the remainder of the day.

Annihilannic.

 

[SamBones]

On my systems it seems to stop recording for the rest of the day when you reboot. But does resume the next day at midnight.