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High latency from statistics system show

Hi all,

 

We just set up a four-node MCC, when we use the command:

I19NF8060::> statistics system show -interval 5 -iterations 25 -max 25

 

We get following results:


I19NF8060 : 12/3/2015 15:57:52
                                 
        CPU *Total Total Latency
 System (%)    Ops (Bps)    (ms)
cluster   2     11 20316  340000

I19NF8060 : 12/3/2015 15:57:56
cluster   2      0  8192  500000

I19NF8060 : 12/3/2015 15:58:00
                                 
        CPU *Total Total Latency
 System (%)    Ops (Bps)    (ms)
cluster   2      1 11392  600000

I19NF8060 : 12/3/2015 15:58:05
cluster   2      9 16252  404000

I19NF8060 : 12/3/2015 15:58:09
                                 
        CPU *Total Total Latency
 System (%)    Ops (Bps)    (ms)
cluster   2      0  8192       0

I19NF8060 : 12/3/2015 15:58:13
cluster   2     11 20316  445000

 

The latency is too high for a new and even empty system (just have a SVM for some testing).

 

Do you have any ideas of how to find the reason about such high latency?

 

Best Regards,

Jeff Cai

 
 
 
 
 

Re: High latency from statistics system show

Hi,

 

You can check the ASUP logs or run the perfstat tool for additional information. Also refer the following kb "https://kb.netapp.com/support/index?page=content&id=2023701&actp=LIST_RECENT&viewlocale=en_US&searchid=1449202331051"

 

Hope this helps.

 

If this post resolved your issue, help others by selecting ACCEPT AS SOLUTION or adding a KUDO.

Re: High latency from statistics system show

Hi Jeff,

 

what is it exactly that you are trying to show? My first guess is you are looking at the wrong output or using the wrong command.

 

If I take the demo MCC in Munich, which has just 5m distance between the two "sites", I see very similar numbers with that command:

 

optimus::> statistics system show -interval 5 -iterations 25 -max 25

optimus : 12/4/2015 11:08:01

        CPU *Total Total Latency
 System (%)    Ops (Bps)    (ms)
------- --- ------ ----- -------
cluster   5      3  7017  250000

optimus : 12/4/2015 11:08:05
cluster   7      3  2664  142000

optimus : 12/4/2015 11:08:09

        CPU *Total Total Latency
 System (%)    Ops (Bps)    (ms)
------- --- ------ ----- -------
cluster   5      2  3945  272000

optimus : 12/4/2015 11:08:13
cluster   2      1   959  400000

optimus : 12/4/2015 11:08:17

        CPU *Total Total Latency
 System (%)    Ops (Bps)    (ms)
------- --- ------ ----- -------
cluster   4      3  1127  538000


optimus::>

 

Even if I put load on the system (VM running in NFS datastore) the values basically don't look any better:

 

optimus::> statistics system show -interval 5 -iterations 25 -max 25

optimus : 12/4/2015 11:10:42

        CPU *Total   Total Latency
 System (%)    Ops   (Bps)    (ms)
------- --- ------ ------- -------
cluster   6   1737 9089108 5020000

optimus : 12/4/2015 11:10:46
cluster   4   1743 8754472 5008000

optimus : 12/4/2015 11:10:50

        CPU *Total   Total Latency
 System (%)    Ops   (Bps)    (ms)
------- --- ------ ------- -------
cluster   6   1736 8726654 5028000

optimus : 12/4/2015 11:10:54
cluster   5   1746 9228116 4998000

optimus : 12/4/2015 11:10:58

        CPU *Total   Total Latency
 System (%)    Ops   (Bps)    (ms)
------- --- ------ ------- -------
cluster   5   1746 9296850 5010000

optimus : 12/4/2015 11:11:02
cluster   7   1681 7337343 5173000


optimus::>

 

But the reality is, that the VM I'm testing with is doing IO on a mixed 100% random 50% read/write workload at 4.5ms latency and 100% write at 0.5ms latency.

 

This matches the IO_meter output as well as the ONTAP volume statistics:

 

io_meter.png

 

 

optimus::> statistics volume show -interval 5 -iterations 10 -max 25

optimus : 12/4/2015 11:13:06

                                             *Total Read Write Other    Read   Write Latency
                 Volume              Vserver    Ops  Ops   Ops   Ops   (Bps)   (Bps)    (us)
----------------------- -------------------- ------ ---- ----- ----- ------- ------- -------
svm_optimus_esx_demo_ds svm_optimus_esx_demo   1744  869   874     0 3561728 3570216    4361

[...truncated...]

 

 

So I assume the command you are using is not showing what you are looking for.

 

Kind regards, Niels

 

 

Re: High latency from statistics system show

Hi Niels,

 

Much appreciate your help.

 

Maybe it's a bug for the result?

 

Thanks,

Jeff