Clients are observing high latency when Vscan is enabled due to the Vscan servers being overloaded

Applies to

• ONTAP 9
• CIFS
• Vscan

Issue

• Clients are observing high latency when Vscan is enabled
  • Example: Jobs that normally take 10-12 minutes take over an hour
• High latency is seen in the Network column of qos statistics volume latency show infrequently
  • Note: Sometimes no latency is seen and must be checked against qos statistics volume performance show to see offbox latency

Cluster1::> qos statistics volume latency show -volume vol1 -vserver svm1
Workload            ID    Latency    Network    Cluster       Data       Disk        QoS      NVRAM
--------------- ------ ---------- ---------- ---------- ---------- ---------- ---------- ----------
-total-              -     5.52ms     4.41ms    15.00us   981.00us   113.00us        0ms        0ms
vol1             10210      4.60s      4.59s     6.00us    91.00us    12.00us        0ms        0ms
-total-              -    85.00us        0ms        0ms        0ms        0ms        0ms        0ms
vol1             10210    84.00us        0ms        0ms        0ms        0ms        0ms        0ms

• Errors may be seen like below:

Wed Jul 06 00:20:15 EEST [cluster1-02: kernel: Nblade.vscanBadUserPrivAccess:error]: 
    For Vserver "svm1", the attempt to connect to the privileged ONTAP_ADMIN$ share 
    by the client "10.1.2.3" is rejected because its logged-in user "VSCAN-admin" 
    is not configured in any of the Vserver active scanner pools.
Wed Jul 06 00:20:16 EEST [cluster1-02: kernel: Nblade.vscanConnBackPressure:error]: 
    For Vserver "svm1", AV server "10.1.2.3" is too busy to accept new scan requests.