Skip to main content
NetApp Knowledge Base

How ONTAP implements SMB crediting

  1. Last updated
  2. Save as PDF
Views:
6,066
Visibility:
Public
Votes:
8
Category:
ontap-9
Specialty:
nas
Last Updated:

Applies to

  • ONTAP 9.4 and later
  • SMB2 and higher

Answer

  • In ONTAP 9.4, throttling of SMB credits was implemented via a maximum credits configuration
    • Prior to 9.4, SMB clients were granted as many credits as they requested
    • By default, ONTAP 9.4 grants 128 credits per connection
  • Display the current max-credits value:

cluster1::*> set -privilege advanced
cluster1::*> vserver cifs options show -vserver svm1 -fields max-credits

  • Modify max-credits value:

cluster1::*> vserver cifs options modify -vserver svm1 -max-credits 512

Additional Information

  • Modified credit value will only take effect on new cifs sessions
  • SMB credits determine the number of outstanding simultaneous requests that the client can have on a particular connection.
  • The allowed range is between 2 and 8192
    • Default value does not need to be changed unless issue is confirmed to be root cause or vendor states a specific number of credits are needed.
      • Follow client vendor recommendations if it differs from the default
    • While it is possible to set number of credits to 2, there have been reports that some clients start to misbehave with such a low setting
      • Changing the max-credits value is not expected to cause any issues
      • Recommendation: Test changes on a test SVM with test clients prior to making the change on a production SVM.
        • To troubleshoot, slowly increase the value until the issue is resolved
  • As documented in this Microsoft Docs page, Performance tuning for SMB file servers, Windows now defaults to 512 credits.
  • For assistance with disabling SMB crediting, contact NetApp Technical Support and reference this article.

 

NetApp provides no representations or warranties regarding the accuracy or reliability or serviceability of any information or recommendations provided in this publication or with respect to any results that may be obtained by the use of the information or observance of any recommendations provided herein. The information in this document is distributed AS IS and the use of this information or the implementation of any recommendations or techniques herein is a customer's responsibility and depends on the customer's ability to evaluate and integrate them into the customer's operational environment. This document and the information contained herein may be used solely in connection with the NetApp products discussed in this document.