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Mix FC speed

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  • 1.  Mix FC speed

    Posted 11-22-2013 03:10 AM


    We have a HP C7000 with HP branded brocade 4Gb FC SAN Switches. We connect to two rack based 8Gb. Brocade Switches where we got different storage systems (EVA, MSA) all 4Gb.

    We just connected our 3PAR Storage newcomer and with 8Gbit HBA. The performance was horrible. If I set the FC ports to 4Gb Fixed the performance is fine.

    Maybe my understanding of how mix of FC port speed works is wrong? Our entire FC infrastructure was running 4GB until we got our 3par so I did not think twice about it.

    We are about to install another c7000 with 8gbit FC and it would be a pity to force it down to 4GB



  • 2.  Re: Mix FC speed

    Posted 11-22-2013 04:40 AM

    Mixing speeds in an FC environment is supported but there can be pitfalls.


    First did you follow and obey the HP ruling in there SAN Design reference guide?

    There are some pointers on 8GB ports and they've written seperate rules for 3Par and again seperately rules for Bladed switches


    Make sure you follow the rules applying to your environment.

    If you are unsure caal HP support, with that many HP gear you surely have an support contract that will cover this or this may still be covered with the installation service you may have bought.


    As to the performance being horrible, it might me because rules aren't followed or if rules were followed indeed issues in the fabric.

    Its hard to tell without knowing how stuff is interconnected.


    So in a nutshell goto HP and/or supply more info, like topology and were the 8GB HBA and 3Par are connected to etc.


  • 3.  Re: Mix FC speed
    Best Answer

    Posted 11-29-2013 06:07 AM

    It turns out that HP get there SFP produced in at least two different companies (Avago and Finisar) and label them with the same product number, they don’t have the same finish on the casing though


    The only way to spot the difference is to get the information from CLI (supportshow). 

    (HP-A) SFPs require replacement (Avago)
    (HP-F) is fine (Finisar)


    I've created a CASE and this is a known issue but no information is public. They are going to fix this with a firmware but I got mine replaced.