rhel6/7: problem with network statistics reported by sysstat

Solution Verified - Updated -

Issue

  • The net statistics reported by the sar application are wrong, more than twice the real traffic. You can see in the following copy-n-paste the big difference between the statistic reported from sysstat in the RPM repository:

    Average:        IFACE   rxpck/s   txpck/s
    Average:        bond0  11342.37  16948.02
    

    Sysstat compiled from sources shows lower values, which also match the values reported by ifconfig:
    and the statistics reported by sysstat compiled from sources:

    # ifconfig bond0 | egrep -o 'RX packets:[0-9]+' 
    # sleep 5
    # ifconfig bond0 | egrep -o 'RX packets:[0-9]+'
    RX packets:16831578535
    RX packets:16831599072
    
  • The values of rxpck/s and txpck/s of sar increased even though the number of packets /proc/net/dev showed was not increasing:

    12:00:01 AM IFACE     rxpck/s   txpck/s      rxkB/s    txkB/s   rxcmp/s   txcmp/s  rxmcst/s
       :
    11:50:01 AM  qvo1        0.55      0.40        0.05      0.05      0.00      0.00      0.00
    11:50:01 AM    lo       14.38     18.38        0.94      0.94      0.00      0.00      0.00
    11:50:01 AM  tap1        0.55      0.40        0.05      0.05      0.00      0.00      0.00
    11:50:01 AM eth_2 23282939.17  72342.13 43105104.33   9231.02      0.00      0.00  80234.34
                       ^^^^^^^^^^^^^^^^^^^^^
    

    The raw values in /proc/net/dev make sense, but the values from sar do not. What is the reason?

Environment

  • Red Hat Enterprise Linux 6 and 7
  • sysstat, versions <11.3.2

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