Windows Explorer hangs for a couple of seconds while opening or renaming the folders on FlexGroup CIFS share in ONTAP 9.4+

Applies to

• ONTAP 9.4 or higher
• CIFS share
• Flexgroups

Issue

1. Windows Explorer hangs for a couple of seconds while opening or renaming the folders.
2. Long delay for SMB Create responses could be confirmed from the packet traces; the longest delay is up to 3 or 4 seconds. 

WireShark\SMB2 Service Response Time Statistics
 

Find out the long running Create responses using the following filter:
smb2.cmd == 5 && smb2.time >=3
This will list out all the SMB2 Create responses that take longer than 3 seconds.

All these long running responses are Compound Requests: Create + Notify


In perfstat, the only delayed responses (in the range of 2s ~ 4s are from SMB Notify requests, while the SMB CREATE requests do not witness any high latency outliers. This is different with the observations from packet traces. 
smb2:svm_name:latency_histogram.<1s:0
smb2:svm_name:latency_histogram.<2s:0
smb2:svm_name:latency_histogram.<4s:4
smb2:svm_name:latency_histogram.<6s:0
smb2:svm_name:latency_histogram.<8s:0
smb2:svm_name:latency_histogram.<10s:0

smb2:svm_cifs:create_latency_histogram.<1s:0
smb2:svm_cifs:create_latency_histogram.<2s:0
smb2:svm_cifs:create_latency_histogram.<4s:0
smb2:svm_cifs:create_latency_histogram.<6s:0
smb2:svm_cifs:create_latency_histogram.<8s:0
smb2:svm_cifs:create_latency_histogram.<10s:0

smb2:svm_cifs:change_notify_latency_histogram.<1s:0
smb2:svm_cifs:change_notify_latency_histogram.<2s:0
smb2:svm_cifs:change_notify_latency_histogram.<4s:4
smb2:svm_cifs:change_notify_latency_histogram.<6s:0
smb2:svm_cifs:change_notify_latency_histogram.<8s:0
smb2:svm_cifs:change_notify_latency_histogram.<10s:0