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Heavy SMB signing pressure causes high SMB3 latency from Network CPU domain

Views:
176
Visibility:
Public
Votes:
0
Category:
ontap-9
Specialty:
perf
Last Updated:

Applies to

ONTAP 9

SMB3

SMB2

Issue

  • High SMB latency from Unified Manager, Grafana, Perfstat/PerfArchive. In the latency breakdown section, the bulk of the latency is from CPU_network or CPU N-blade, depending on the tools that are used to monitor performance
  • The impacted Vservers have a big amount of SMB3 or SMB3.1 connections
    • cifs:vserver_name:total_smb3_connections_count:100000
    • cifs:vserver_name:total_smb3_1_connections_count:100000
  • The impacted Vservers have signed sessions, as well as a significant amount of data being signed per second
    • cifs:vserver_name:signed_sessions:50
    • smb2:vserver:bytes_signed_rate:20000000b/s
  • Network CPU is not necessarily saturated
    • Avg CPU util might NOT be high
    • Nwk_Exmpt CPU domain util might not be higg
  • Other protocols might be impacted as well, such as NFS or iSCSI. As they have to complete for the same network threads with SMB signing workload
  • The util of NwkThd threads isn't necessarily high in ps
  • The average on queue time for NwkThd threads isn't necessarily high in ps -s 
   ID   RunCount   RunMax  RunAve   OnQMax OnQAve Pri D Name
  272    2469043     2498      21    39726      3 100 N NwkThd_00

 

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