CIFS multi point performance issues

[JohnsonSean]

Settup

FAS 2552 with additional shelf Running ONTAP 9.1P2 (24x2 disk 10k SAS)

2 Heads 1 10G per head

FAS 2552 <> 16port 10G NetApp switch <> 10G Trunk <> CISCO 3850X SW (48p 1G 2x10G) <> several servers at 1G

Servers are 2012r2, clients Windows 10 (all 1G connections from the same switch hosting the 10G trunk to NetApp sw)

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I'm fairly new to CDOT and have limited experiance with network storage.

My issue is that the CIFS share on this device are caping out at about 1G throughput. IE Server1 starts a file copy from the share at full Gig speeds, Server2 begins copying from it and the transfer rate drops to half a Gig for each. I can copy from multiple NetApps at full 1G each but am unable to get any NetApp share to exceed 1G througput.  

To isolate this to a CIFS issue I had three servers and the FAS conect with ISCSI. After creating three LUNS and connecting them to three physicaly seperate servers on the same switch, I observed 3 seperate full 1Gig connections simultainous.

The network should be capable of pushing around 10 1G connections through that trunk port as it did for the ISCSI connection, not sure what to look at next.

This is our current "vserver cifs options show" with advanced priv set.

Vserver: svm1

                            Client Session Timeout: 900
                              Copy Offload Enabled: true
                                Default Unix Group: -
                                 Default Unix User: pcuser
                                   Guest Unix User: -
               Are Administrators mapped to 'root': true
           Is Advanced Sparse File Support Enabled: true
                  Direct-Copy Copy Offload Enabled: true
                           Export Policies Enabled: false
            Grant Unix Group Permissions to Others: false
                          Is Advertise DFS Enabled: false
     Is Client Duplicate Session Detection Enabled: true
               Is Client Version Reporting Enabled: true
                                    Is DAC Enabled: false
                      Is Fake Open Support Enabled: true
                         Is Hide Dot Files Enabled: false
                              Is Large MTU Enabled: true
                             Is Local Auth Enabled: true
                 Is Local Users and Groups Enabled: true
            Is NetBIOS over TCP (port 139) Enabled: true
               Is NBNS over UDP (port 137) Enabled: false
                               Is Referral Enabled: false
             Is Search Short Names Support Enabled: false
  Is Trusted Domain Enumeration And Search Enabled: true
                        Is UNIX Extensions Enabled: false
          Is Use Junction as Reparse Point Enabled: true
                               Max Multiplex Count: 255
              Max Same User Session Per Connection: 2050
                 Max Same Tree Connect Per Session: 4096
                      Max Opens Same File Per Tree: 800
                          Max Watches Set Per Tree: 100
                   Is Path Component Cache Enabled: true
    NT ACLs on UNIX Security Style Volumes Enabled: true
                                  Read Grants Exec: disabled
                                  Read Only Delete: disabled
                  Reported File System Sector Size: 4096
                                Restrict Anonymous: no-restriction
                              Shadowcopy Dir Depth: 5
                                Shadowcopy Enabled: true
                                      SMB1 Enabled: true
                  Max Buffer Size for SMB1 Message: 65535
                                      SMB2 Enabled: true
                                      SMB3 Enabled: true
                                    SMB3.1 Enabled: true
            Map Null User to Windows User or Group: -
                                      WINS Servers: -
         Report Widelink as Reparse Point Versions: SMB1