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Slow Network with SEA on DUALVIOS 4.1.0.10 on IBM i 7.5

  • 1.  Slow Network with SEA on DUALVIOS 4.1.0.10 on IBM i 7.5

    Posted Mon October 28, 2024 11:01 AM

    Hi,

    we have an Power 10 System configured with DUAL-VIOS. The Client LPAR ist an IBM i with 7.5 and all latest PTF installed.

    FTP Connection is running fast. But 5250, Navigator for i and outgoing SSH Connection is very slowly.

    The ETHLINE are attached to Shared Ethernet Adapter which are configured als Load-Sharing and failover. Could this be the Problem ?



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    Riccardo Singh
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  • 2.  RE: Slow Network with SEA on DUALVIOS 4.1.0.10 on IBM i 7.5

    Posted Mon October 28, 2024 08:14 PM
    Edited by Satid S Mon October 28, 2024 08:33 PM

    Dear Riccardo

    What is the CPU power and memory size you allocate for both VIOS?   What Power server model you are using? 

    Are you sure you implemented SEA failover and not the better vNIC failover?   You should implement VIOS vNIC failover instead:  https://community.ibm.com/community/user/power/blogs/charles-graham1/2020/06/19/vnic-failover-in-powervm-225   and   https://community.ibm.com/HigherLogic/System/DownloadDocumentFile.ashx?DocumentFileKey=87f897df-6a7e-fcf1-5743-abef1b382d4d&forceDialog=0     

    To check any sign of problem on IBM i side, please display your IBM i ETHLINE description to see its current reported status for the speed and duplex to make sure they show proper values (say, in full GB of the physical LAN interface and full duplex). Also run WRKPRB to check if you see any error involving your Ethernet line resource name or not?

    Next, please check the screens of WRKSYSSTS and WRKSYSACT.   In WRKSYSSTS, you should see proper allocation of memory pools as well as proper value of MAX ACT for each.  In WRKSYSACT, you should see proper assignment of virtual processor in relation to allocated processor and you want to see at least 100% value (when there is workload running) of CPU Rate.   You can post the screens here for me to see if you want.



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    Satid S
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    Original Message


  • 3.  RE: Slow Network with SEA on DUALVIOS 4.1.0.10 on IBM i 7.5

    Posted Tue October 29, 2024 03:26 AM

    Hi,

    both VIOS have 1 CPU and 4 GB RAM

    We are using an IBM Power 19 9105-41B Server

    I used this manual to create the SEA' https://theibmi.org/2016/03/26/how-to-create-sea-with-no-touch-vio/

    So iam sure that there is an SEA configured.

    ETHLINE Description on IBM 

    Leitungsbeschreibung . . . . . . . :   ETHLINE            
    Auswahl  . . . . . . . . . . . . . :   *BASIC             
    Leitungskategorie  . . . . . . . . :   *ELAN              
                                                              
    Ressourcen name  . . . . . . . . . :   CMN08              
    Brücken-ID . . . . . . . . . . . . :   *NONE              
    Bei IPL anhängen . . . . . . . . . :   *NO                
    Wartezeit bei Anhängen . . . . . . :   *NOWAIT            
    Netzwerksteuereinheit  . . . . . . :   ETHLINET00         
    Lokale Adapteradresse  . . . . . . :   020000000001       
    Austausch-ID . . . . . . . . . . . :   05648950           
    Ethernet-Standard  . . . . . . . . :   *ALL               
    Übertragungsgeschwindigkeit  . . . :   *AUTO              
    Aktuelle Übertragungsgeschw. . . . :   *AUTO              
    Duplex . . . . . . . . . . . . . . :   *AUTO              
    Aktueller Duplexwert . . . . . . . :   *AUTO              
    Serviceoptionen  . . . . . . . . . :   *NONE              

     Leitungsbeschreibung . . . . . . . :   ETHLINE                         
     Auswahl  . . . . . . . . . . . . . :   *BASIC                          
     Leitungskategorie  . . . . . . . . :   *ELAN                           
                                                                            
     Maximale Rahmengröße . . . . . . . :   1496                            
     Max. Anzahl Steuereinheiten  . . . :   40                              
     Fehlerschwelle . . . . . . . . . . :   *OFF                            
     Testrahmen generieren  . . . . . . :   *YES                            
     Nachricht- warteschl.  . . . . . . :   *SYSVAL                         
     Akt. Nachrichtenwarteschlange  . . :   QSYSOPR                         
       Bibliothek . . . . . . . . . . . :     QSYS                          
     Text . . . . . . . . . . . . . . . :   Schnittstelle während Testphase 

    WRKSYSSTS



    ------------------------------
    Riccardo Singh
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    Original Message


  • 4.  RE: Slow Network with SEA on DUALVIOS 4.1.0.10 on IBM i 7.5

    Posted Wed October 30, 2024 12:41 PM

    Is "Lokale Adapteradresse  . . . . . . :   020000000001" the LAA of the card ?  If so, are you certain that there is no other system/LPAR/VM with the same LAA ?



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    José Pina Coelho
    IT Specialist at Kyndryl
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    Original Message


  • 5.  RE: Slow Network with SEA on DUALVIOS 4.1.0.10 on IBM i 7.5

    Posted Tue October 29, 2024 11:42 AM

    When I hear SEA and slow networking on an IBM i client, my first thought is to check Large Send Offload.  Make sure your SEA and it's child adapters are configured to allow large send offload:

    https://www.ibm.com/support/pages/how-determine-if-large-send-offload-lsolargesend-and-large-receive-offload-lrolargereceive-are-enabled-sea



    ------------------------------
    Vincent Greene
    IT Consultant
    Technology Expert labs
    IBM
    Vincent.Greene@ibm.com


    The postings on this site are my own and don't necessarily represent IBM's positions, strategies or opinions.
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    Original Message


  • 6.  RE: Slow Network with SEA on DUALVIOS 4.1.0.10 on IBM i 7.5

    Posted 30 days ago

    Hi, sorry for the late answer. But this was the solution. Thanks a lot!



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    Riccardo Singh
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    Original Message


  • 7.  RE: Slow Network with SEA on DUALVIOS 4.1.0.10 on IBM i 7.5

    Posted Thu January 23, 2025 08:27 AM

    Hard to say, but very unlikely it will be the SEA problem. Maybe some hardware, connection, cable issue. 5250 traffic is small TCP packets, more depending on response time than bandwidth. I would run TCP dump and investigate  in WireShark which packets take too much time to respond. 

    I always use Load-sharing with fail-over functionality, it has never been a reason to slow down the response time. 



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    Bartlomiej Grabowski
    IBM Champion - Platinum Redbook Author and Principal System Specialist
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    Original Message


  • 8.  RE: Slow Network with SEA on DUALVIOS 4.1.0.10 on IBM i 7.5

    Posted Fri January 24, 2025 04:43 AM

    I'd add to that, to check the resource utilisation on the VIO, insufficient CPU will cause the VIO to add latency to the network.  Checking the SEA for any hypervisor send/receive issues (insufficient vEth buffers) is also advisable. 

    Insufficient vEth buffer causes NFS performance problems for client LPARs.  NFS like 5250 uses a lot of small packets and uses a lot of buffers in the vEth adapters that are part of the SEA.

    Phill.



    ------------------------------
    Phill Rowbottom
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    Original Message


  • 9.  RE: Slow Network with SEA on DUALVIOS 4.1.0.10 on IBM i 7.5

    Posted Fri January 24, 2025 01:53 AM

    Hi,


    could it be the case that "accounting" is enabled on the SEA adapter?
    If so consider to change it to disabled on both VIOS one by one. It is possible there are delays during this state change as the ha_mode "sharing" is switching for a brief moment on both VIOS.



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    Patrick Hügli
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    Original Message


  • 10.  RE: Slow Network with SEA on DUALVIOS 4.1.0.10 on IBM i 7.5

    Posted Fri January 24, 2025 01:43 PM

    Hi,

    You can run tue "part" command on VIOSs.

    The "part" stands for "Performance Advisor Report Tool". You have to specify the time for collecting (part -i 10, for 10 minutos, for example).

    This will generate a tar file and inside that a xml file.

    Open the xml file in your browser.

    There, you can see all recomendation for VIOS configuration.

    You will see a report like this:



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    Adalberto Giaretta
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    Original Message


  • 11.  RE: Slow Network with SEA on DUALVIOS 4.1.0.10 on IBM i 7.5

    Posted 30 days ago

    I would definetely check Large send and Jumbo frame :

    I had the same problem with slow Navigator because of Large send not selected



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    Pino Mariotto
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    Original Message


  • 12.  RE: Slow Network with SEA on DUALVIOS 4.1.0.10 on IBM i 7.5

    Posted 30 days ago

    Hello Pino, yes the LargeSend was the Problem. I've made the changes as described in the following link from vincent.

    https://www.ibm.com/support/pages/how-determine-if-large-send-offload-lsolargesend-and-large-receive-offload-lrolargereceive-are-enabled-sea



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    Riccardo Singh
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    Original Message