IBM Support

NetServer support of SMB2 at V7R3 and support for Change Notify

Technote (troubleshooting)


Problem(Abstract)

Microsoft Windows Explorer performs an endless, rapid, refresh of a network drive that is mapped to a NetServer share, preventing the user from performing tasks such as rename object.

Symptom

Microsoft Windows Explorer performs an endless, rapid, refresh of a drive mapped to a NetServer share. This prevents the user from paging through the file list and performing tasks such as rename object, etc.


Cause

Microsoft Windows Explorer is ignoring a STATUS_NOT_SUPPORTED response that is returned to it from the IBM i server on a Change Notify request.

Environment

IBM i Server V7R3, SMB2, Microsoft Windows 7, 8.x, and Windows 10.

Diagnosing the problem

If the arrows on folders are flashing on/off when in Windows Explorer with the mouse cursor in the navigation pane, then that is very likely an indicator that the issue described in this document is occurring.

For additional confirmation, with the mapped drive established but no user activity, minimize Windows Explorer. Open a PC5250 session and issue command NETSTAT *CNN, press F14, F11, F15, set Local Port Range Lower Value to 445, press Enter twice to see the Bytes Out and Bytes In. Press F5 multiple times to refresh and see if the Byte count increases rapidly for the idle device. If the Byte count increases rapidly, you are probably experiencing the problem.

Another more concrete confirmation would require the collection and analysis of IBM i Communications and Wireshark traces, showing that this problem is taking place where the client is in a refresh loop and ignoring STATUS_NOT_SUPPORTED.


Resolving the problem

NetServer is protocol compliant and changes need to be made on the client to avoid wasting resources. Contact Microsoft Support to address this issue with the Windows Explorer application.

Possible alternative solutions to access the IFS objects on the IBM i server include:

1
Upgrade to Windows 10 PC OS and apply the current updates. Microsoft has released a fix for this issue in Windows 10. NOTE: This Microsoft fix resolves the constant refreshes from Windows 10 clients. However, at this time Microsoft has chosen not to fix Windows versions prior to Windows 10. You may contact Microsoft support for a fix a Windows 7, 8.x, and other Windows Operating Systems.

The Microsoft KB4015217 for the Windows 10 fix is here: https://support.microsoft.com/en-us/help/4015217

"Addressed an issue that was causing Windows Explorer to perform an endless, rapid refresh of a network drive that is mapped to a share, preventing users from performing tasks such as rename object."

Ensure the current PTFs for NetServer, and related functions, are applied for your IBM i server.
2 Use File Systems in IBM System i Navigator.
3 Use a SAMBA client to connect to the IBM i NetServer shares. Additional details on IBM i support for Samba is available in IBM Technote N1020089, found online at:

http://www.ibm.com/support/docview.wss?uid=nas8N1020089

4 Disable Microsoft Change Notify

    NOTE: This solution involves a change in the PC Registry..

    Caution: Serious problems might occur if the registry is modified incorrectly by using the Registry Editor or by using another method. These problems might require that you reinstall your operating system. IBM cannot guarantee that these problems can be solved. IBM does not support the process of modifying the PC registry. Modify the registry at your own risk.

    NOTE: Change Notify is a Microsoft function. IBM supports neither Microsoft Windows nor Change Notify. Assistance with this solution will need to come from Microsoft Support. The information below is provided as a courtesy only.


    Microsoft has a way to turn off directory notification SMB requests in Windows XP, visit URL:

    https://support.microsoft.com/en-us/kb/812669

    NOTE: The Microsoft URL above was valid at the time this document was written. IBM cannot guarantee validity of Microsoft URLs. If the link does not work, try searching for Microsoft 812669 or for the title of the document, which is "An update is available in Windows to turn off directory notification SMB requests".

    NOTE: This functionality was added as a HotFix in Windows XP in 2003 and was configured as shown here. Testing shows that this fix works on Windows 7 as well as Windows XP.

    Turn off Change Notify requests for all users
    a. Click Start, click Run, type regedit in the Open box, and then click OK.
    b. Locate and then click the following registry key:HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Explorer
    c. On the Edit menu, point to New, and then click DWORD Value.
    d. Type NoRemoteChangeNotify, and then press ENTER.
    e. On the Edit menu, click Modify.
    f. Type 1 in the Value data box, and then click OK.
    g. Quit Registry Editor.
    h. Reboot the PC and map a drive to the NetServer share.

    NOTE: The Microsoft document also provides steps on how to make the change to the currently logged on user.

5 Use FTP client.
6 Use NFS mount.
7 Disable SMB2 on the IBM i server.


In V7R3 Memo to users, under the IBM i NetServer Shared Printer Changes section, the following is documented:

There is a new version of the Server Message Block (SMB) protocol. Version 2 (SMB2) has been added and is now the default that is negotiated with IBM i NetServer clients. The following command can be used to permanently disable SMB2 support for IBM i NetServer:

    CALL QZLSMAINT PARM('40' '1' '0x80')

NOTE: This will disable SMB2 for both Printer and File shares.
    a. Stop NetServer: ENDTCPSVR SERVER(*NETSVR)
    b. Disable NetServer SMB2: CALL QZLSMAINT PARM('40' '1' '0x80')
    c. Start NetServer: STRTCPSVR SERVER(*NETSVR)
    d. NetServer client's (user PC) that were mapped using SMB2 protocol will need to reboot their PC because of Windows security precautions.

If for some reason disabling SMB2 does not help alleviate the problem, then SMB2 can be re-enabled using the same steps as above, but replacing the command in step b with the following command:
    CALL QZLSMAINT PARM('40' ' 2 ' '0x80')


Cross reference information
Segment Product Component Platform Version Edition
Operating System IBM i 7.3
Operating System IBM i 7.2

Document information

More support for: IBM i

Software version: 7.2, 7.2.0, 7.3

Operating system(s): IBM i

Reference #: N1021348

Modified date: 18 August 2017


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