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High rate of Zero BB Credits per seconds on E-Ports

  • 1.  High rate of Zero BB Credits per seconds on E-Ports

    Posted 01-13-2014 08:07 AM

    Hi,

    We are monitoring some customer's brocades environment.

    There are two fabrics:

    each fabric contains Brocade5100, connected to Brocade300 using two E-Ports.

    On each E-Port I can see a high rate of average Zero BB credits/sec.

     

    What is likely can be the cause?

    Ports speed are 8gb, and the are not utilized at all.

     

    Thanks

    Amir


    #BrocadeFibreChannelNetworkingCommunity


  • 2.  Re: High rate of Zero BB Credits per seconds on E-Ports

    Posted 01-13-2014 12:34 PM

    Can you post a diagram of how the swithes are interconnected and which ports on which switches have the targets (ie storage) attached?

     

    Also what do you consider high rate? And how does it compare against the number of frames.

    Do you have historic data which you can share. If you don't have data you can clear the statistics and and wait 15 mins or so and post the figures. portstatsshow will show post the # of frames and tx credit zero against all VC's


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  • 3.  Re: High rate of Zero BB Credits per seconds on E-Ports

    Posted 01-13-2014 06:53 PM


  • 4.  Re: High rate of Zero BB Credits per seconds on E-Ports

    Posted 02-17-2014 12:56 AM

    Hi,

    Thanks for your comments, but still didn't understood the cause for this.

    There are two issuses, and I see it from both of the switches:

    Some ESX server is doing lots Zero BB/sec, comparing to the other ESXs (see attached report).

    Also, on the E-Ports I see a high rate comapring to the rest of the ports.

     

    It will be great if you can advise what can be the cause.

     

    Attached:

    1. Fabrics topology

    2. Reports shows the ports statistics.

    3. statsportsshow for the following port from each brocade:

        a. port 8 (ESX)

        b. ports 27 & 31 (E-Ports)  

     

    Thanks


    #BrocadeFibreChannelNetworkingCommunity

    Attachment(s)



  • 5.  Re: High rate of Zero BB Credits per seconds on E-Ports

    Posted 02-17-2014 06:32 AM

    You may want to check your fillword settings on the ISL links.

     

    Several ports are showing er_bad_os. This might indicate a fillword issue.

     

    Run portcfgshow | grep Fill

     

    Fillword should be 3 for all 8 G ports.

     

    Note, changing an ISL links fillword might require special planning and downtime.


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  • 6.  Re: High rate of Zero BB Credits per seconds on E-Ports

    Posted 03-19-2014 02:42 AM

    Hi,

    If we change the fillword to 3 on one 8gb port, will it reset this port only, or affect more ports ?

    Assuming we have two links to the switch, the question is if we can change one port at a time.

     

    Thanks


    #BrocadeFibreChannelNetworkingCommunity


  • 7.  Re: High rate of Zero BB Credits per seconds on E-Ports

    Posted 03-19-2014 06:42 AM

    portcfgfillword works on a per port basis. so one port is affect at a time, mind you if that port is a trunkport the trunk it belongs to is affected as well.


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  • 8.  Re: High rate of Zero BB Credits per seconds on E-Ports

    Posted 03-19-2014 06:44 AM

    Thanks, can you please advise how to check if the ports are trunked ?

     

    Thanks


    #BrocadeFibreChannelNetworkingCommunity


  • 9.  Re: High rate of Zero BB Credits per seconds on E-Ports

    Posted 03-19-2014 08:04 AM

    trunkshow

     

    admin> trunkshow
    1: 4-> 4      10:00:00:xx:xx 2 deskew 16 MASTER
         5-> 5     10:00:00:xx:xx 2 deskew 15

    2: 25-> 25 10:00:00:xx:xy 30 deskew 15 MASTER

    3: 26-> 26 10:00:00:xx:xy 30 deskew 15 MASTER

     

    trunk 1 consists out of ISL on port 4 and 5


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  • 10.  Re: High rate of Zero BB Credits per seconds on E-Ports

    Posted 03-19-2014 08:13 AM

    Just checked and we have no trunks.

    So some more questuions:

    1. The fill word should be on any 8gb port ? Only ISL port ?

    2. Does it require some configuration on the ISL port on the other switch ?

    3. Does the fill word can be realted to the high rate of Zero BB credits ?

    4. Other things need to consider before chnaging the fill word ?

     

    Thanks !


    #BrocadeFibreChannelNetworkingCommunity


  • 11.  Re: High rate of Zero BB Credits per seconds on E-Ports

    Posted 03-19-2014 09:43 AM

    1-best partice = mode 3 for the fill word on all 8Gb port, if memory serves me correct

    2-yes best to keep the settings the same on both end, unless the platform does not support it

    3-could be, only one way to find out, alternatively your average framesize is smaller than anticipated, consider recalculating the framessize and adjust the distance if needed

    4-changing fillword is disruptive to the port

     

    Calculating the required credits been posted on the forum before

    Look at http://community.brocade.com/t5/Fibre-Channel-SAN/Long-Distance-Design-Buffer-Credits/td-p/29147

    http://community.brocade.com/t5/Mainframe-Solutions/Buffer-Credits-and-Frame-Size-calculation-in-FOS-7-1/ba-p/455


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