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Aix monitoring tools

Posted on 2009-02-19
Medium Priority
Last Modified: 2013-11-17
hi expert,
      vmstat,sar,netstat,iostat  i what to know thum roles of this command , i need clear understating abt this commands, pls help me out? any suggestion like when running vmstat what need to be check ? how? What is rule?




Question by:Maddy
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omarfarid earned 150 total points
ID: 23681392
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woolmilkporc earned 1350 total points
ID: 23681648
Hi again sivaji,
sar is a collector for system activities in the following areas -
       *    System Configuration Parameters
       *    System unit utilization counters
       *    Buffer usage counters
       *    Disk and tape I/O activity counters
       *    Tty device activity counters
       *    Switching and subroutine counters
       *    File access counters
       *    Queue activity counters
       *    Interprocess communication counters
The result is sort of a system usage summary, which can be used for long-term analysis or planning purposes.
The ...stat utilities are used to visualize system statistics calculated as averages or sums in the interval you specify.
The vmstat command reports statistics about kernel threads, virtual memory, disks, traps and CPU activity.
The netstat command displays the contents of various network-related data structures for active connections.
The iostat command is used for monitoring system input/output device loading
These utilities can be used for shorter-term monitoring, mainly for making decisions how to balance system load activity (vmstat), balance the input/output load between physical disks and adapters (iostat), or balance network load (netstat).
As for rules etc. - system planning and performance tuning are not simple tasks. I'd suggest to read e.g. the following documents/articles first, so that you can ask more specific questions.
Summary of performance commands - http://www.ahinc.com/aix/perform.htm
Redbook -  http://www.redbooks.ibm.com/abstracts/SG246478.html
Practical view - http://www.ibm.com/developerworks/systems/articles/PerformanceandTuning.html


Author Comment

ID: 23681754
sir my question is ?

if i get any ticket regarding ( memory ,CPU,net(slow)) issuse first what i have to check , how can i come to conclusion its normal or i what to take action , if action what kind of action i what to take..

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woolmilkporc earned 1350 total points
ID: 23681982
In such cases it would be best using 'topas'
It will show you on one screen information about CPU, disk, network, memory.
Have a look at it (simply enter topas ) and see what it does.
To be able to make decisions you will have to watch your machine (using topas or the tools you mentioned in your Q) for a longer time to get a clue what might be normal and what might be a problem.
Watch e.g. the cpu percentage (left upper side ot topas), the disk I/Os (TPS, left middle), and memory (right middle) on several normal days. The left lower area has a list of processes.
The process consuming most CPU is on top. Ask yourself - do I know that process? Is it always on top? Is its CPU usage as it used to be?
The same for disks - which disk is on top? how many TPS (transactins per second)? Same as yesterday, more, less?
Or paging (right middle -pgspin/pgspout) - more than usual? Why? enter 'P' in topas, move the cursor to PAGE/SPACE to have the top memory consuming process on top. Which one is it? More than yesterday? Or is it some process you don't know yet?
Being acquainted to your system's behaviour, you will be able to make decisions.

Author Comment

ID: 23682450
sir !

My one of senior told that if memory issue , we have to see just  SCANRAY (vmstat) if scanray is 300 per second no issue if this abow , 300 per second we have to take care. I asked him what is scanray, he not ready to discuss... sir thanks lots helping me! i like sivaji name :-).

How can improve my knowledge in tuning in (memory,CPU,net,io).

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woolmilkporc earned 1350 total points
ID: 23683142
what your senior meant to say was 'scan rate'. This is a memory attribute which refers to the virtual memory manager's efforts to find free pages. If some process is demanding more memory than can be satisfied using free pages, at utility named 'lrud' (least recently used pages demon) is called which scans the memory for used pages not actually needed that can be moved to swap space, thus freeing memory for the demanding process.
The scan rate is displayed in the 'sr' column of vmstat. An elevated rate means that more memory is needed as there is RAM. This is not really a problem under normal circumstances, as there is swap space ('paging space') on disk where pages not used at that very moment can be 'parked'. Should the rate be too high, however, much time is wasted for input/output operations from/to paging space and for the CPU cycles consumed by lrud.
Thus, your senior is right when saying that a too elevated scan rate is problematic. The scan rate that can be tolerated, however, depends heavily on the efficiency of your machine (cpu) and your disk storage (disk subsystem). '300' may be a good value to decide if there is an issue, but I really can't judge, as I don't know your environment.
btw., the basic format of vmstat is 'vmstat [i] [c]', where [i] is interval in seconds and [c] is number of cycles to display.
How to learn? Please re-read my comment 23681982
Carefully watch your system using the appropriate tools, have some good reading (see the documents omarfarid and I proposed), and should you come across a technical term you don't know yet, don't hesitate to google for it, or come back here and ask.
Cheers, and have success!

Author Closing Comment

ID: 31548748
thanks lots sir

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