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