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iSER Configuration

  • 1.  iSER Configuration

    Posted 10 days ago
    I sold a solution for a client that needed pass through a RQP process. It is a FS7200 with iSER RoCE connectivity for a VMware environment in DELL servers through a DELL Z9100.
    It's a first for us and we are facing some issues in the implementation.
      
    In this document https://www.ibm.com/support/knowledgecenter/ST3FR7_8.4.0/com.ibm.fs7200_840.doc/svc_aboutiser.html it says: "Multiple sessions from iSER hosts, with a maximum of four sessions from one iSER host to each system iSER target."
    In this other document https://www.ibm.com/downloads/cas/DP2BJ2ZJ it says the same: "A maximum of up to four iSER host-attach sessions from an iSER initiator to each target node can be established."
     
    I would like do certify two things:
     
    (1) This is a limitation of the iSER protocol or it's a Flashsystem Software implementation limit ?
    (2) We have little experience with iSCSI/iSER implementations, so I would like to clarify which of this two drawings represents correctly those affirmations:

    If you have experience with this type of implementatio, any tips would be very usefull.

    Thanks in advance for your help!





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    Claiton Zanella
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  • 2.  RE: iSER Configuration

    Posted 10 days ago
    @Tony Sater can you help Claiton? If not, please refer this post to the appropriate person? @Maria Altamirano Borrego​​​​

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    Peter Basmajian
    Worldwide Product Marketing and Advocacy, IBM
    San Francisco CA 720-396-5694
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  • 3.  RE: iSER Configuration

    Posted 7 days ago
    Hi Claiton, I believe we've found someone in development / India who can help so they will get back to you on this thread.
    ​​​

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    Peter Basmajian
    Worldwide Product Marketing and Advocacy, IBM
    San Francisco CA 720-396-5694
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  • 4.  RE: iSER Configuration

    Posted 2 days ago
    Hi Claiton,

    The answers to your 2 questions below:

    1) The limit of 4 paths per FlashSystems node (each node exposes 1 iSER target) is not a iSER protocol limitation. This is imposed by FlashSystems because it has been observed that incremental performance per additional path, beyond 4 paths per node starts reducing. Hence a max of 4 paths per node is seen as the optimal configuration.

    2) Regarding the 2 diagrams, the first one shows 2 paths per node and the second one shows 4 paths per node. Since there are no switches shown in the diagrams, I am assuming that. Both diagrams are within the specified limits of FlashSystems i.e. max 4 paths per host. In the first case user should see 4 paths per vDisk and in the second case user should see 8 paths per vDisk.

    What is unclear to me is what is meant by VHBA. The blue and red lines from the FlashSystems nodes to the ESXi host seem to be physical paths connected to 8 NIC/RDMA ports on the ESXi host. Is that correct?

    Thanks,
    -Subhojit

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    Subhojit Roy
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  • 5.  RE: iSER Configuration

    Posted 2 days ago
    Hi Claiton,

    The answers to your questions below:

    1) 4 paths per node (or per iSER target because there is 1 iSER target per node for FlashSystems today), is not an iSER protocol limitation. FlashSystems implements this limit because we have seen that from performance perspective, a max of 4 paths per node is beneficial. Beyond 4 paths per node, the benefits of having multiple paths starts reducing incrementally.

    2) If I understand it right (there are no switches shown in the diagrams), the first diagram shows 2 paths per node from each ESXi host and the second one is 4 paths per node from each ESXi host. Both are within the limits allowed by FlashSystems. In the first case, 4 paths to each vDisks should be visible on ESXi and in the second case there should be 8 paths per vDisk.

    What is unclear to me is what you mean by VHBA. Those connections (in red and blue) seem to be like physical connections from the FlashSystems nodes to the RDMA/NIC ports on the ESXi box.

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    Subhojit Roy
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