Posted on February 24, 2021 6:41 pm
 |  Asked by Christopher Vickers
 |  150 views
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I’m revising for the Arista Linux exam. Why is iostat not needed on an Arista switch?

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Answered on February 25, 2021 4:28 am

Hi Christopher,

Thanks for reaching out.

Basically "iostat" command in linux is used to check CPU ,disk and Memory statistics.

On Arista devices the same purpose is served by checking "show processes top once" and "show processes top memory once" command's outputs.

The top commands provides a lot of info such as CPU util load avg ,CPU and  Memory utilization of process etc.,

Also shows what agents are consuming how much percentage of resources(CPU/Memory).

Sample Output of above commands:

------------- show processes top once -------------

top - 20:48:33 up 5:00, 3 users, load average: 2.05, 1.45, 1.60
Tasks: 342 total, 1 running, 341 sleeping, 0 stopped, 0 zombie
%Cpu(s): 20.2 us, 1.7 sy, 0.0 ni, 77.7 id, 0.1 wa, 0.2 hi, 0.1 si, 0.0 st
KiB Mem: 32823716 total, 6839204 used, 25984512 free, 249552 buffers
KiB Swap: 0 total, 0 used, 0 free, 3203208 cached

PID      USER        PR        NI         VIRT      RES      SHR     S     %CPU    %MEM    TIME+      COMMAND
12091  aberdan     20          0           28864  8568      5164    S          19.4         0.0      0:00.09     CliShell
2320        root        20          0            834m   495m   319m    S            6.5         1.5       8:48.01      ConfigAgent
2806         root       20          0           659m    101m    69m     S            4.3         0.3       1:06.18      Aaa
12087  aberdan     20          0           16904    9.8m   8800    R            4.3         0.0       0:00.28    top

------------- show processes top memory once -------------

top - 20:48:33 up 5:00, 3 users, load average: 2.05, 1.45, 1.60
Tasks: 340 total, 1 running, 339 sleeping, 0 stopped, 0 zombie
%Cpu(s): 20.2 us, 1.7 sy, 0.0 ni, 77.7 id, 0.1 wa, 0.2 hi, 0.1 si, 0.0 st
KiB Mem: 32823716 total, 6835248 used, 25988468 free, 249552 buffers
KiB Swap: 0 total, 0 used, 0 free, 3203272 cached

PID      USER        PR        NI         VIRT      RES      SHR        S     %CPU    %MEM    TIME+      COMMAND
3245     root           20         0           919m     812m    200m      S       0.0           2.5         20:34.51        Rib
3704     root           20         0          1241m    714m     245m      S       0.0           2.24      8:26.93     SandL3Unicast
2866     root           20         0            935m   602m    148m       S       0.0           1.95      1:37.25        KernelFib
2320     root           20         0            834m   495m    319m       S        0.0           1.5       8:48.18        ConfigAgent

Also we can check the same via python scripts as well on Arista devices.

 

Thanks,

Bhavana.

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Posted by Naveen Chandra
Answered on February 25, 2021 6:03 am

Hi Christopher,

As Bhavana said, on Arista devices, you can use "show processes top once" and "show processes top memory once" commands to check the CPU and memory utilization. Just wanted to share the below article for a detailed explanation of the output.

https://eos.arista.com/understanding-cpu-utilization/

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