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  • Installing iSCSI SAN on existing iSCSI SAN Network

    Hi All,

    I've got a direct connection of iSCSI SAN from my Dell MD3000i into the 2x ESXi 4 host with no switch in between, all of the VM is inside the SAN and running on both hosts.

    If I'd like to put a switch in between and add one more iSCSI SAN so that both SAN can be accessed / shared with the total of 3 ESXi 4 hosts, how shall I approach this ?

    any idea or guideline would be greatly appreciated.

    Do I have to schedule down time or can I change the old IP on the existing iSCSI SAN cable manually one by one without damaging/corrupting the VM operation on existing SAN ?

    Thanks,
    AWT
    Attached Files

  • #2
    Re: Installing iSCSI SAN on existing iSCSI SAN Network

    What are you redundancy options on both the ESX hosts and the storage - do you have 2 redundant nics for both?
    Maish
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    • #3
      Re: Installing iSCSI SAN on existing iSCSI SAN Network

      yes each host has pNIC,

      i was hoping that one single subnet for all iSCSI SAN would be sufficient, plus I also plan to connect additional cable from my vcenter into the iSCSI switch for direct SAN based backup using vstorage API if this is possible ?

      eg. controller 1 SAN 1 should use subnet #1 and controller 2 SAN 2 should use subnet #2

      Comment


      • #4
        Re: Installing iSCSI SAN on existing iSCSI SAN Network

        Albertwt,

        Per a previous post, have a look at this document. It is provided by Dell for best practices on your exact model.

        -Jason
        MCSA/MCSE 2K3,MCITP:ESA,MCTS x 4,VCP x 2

        Comment


        • #5
          Re: Installing iSCSI SAN on existing iSCSI SAN Network

          Originally posted by VWA4 View Post
          Albertwt,

          Per a previous post, have a look at this document. It is provided by Dell for best practices on your exact model.

          -Jason
          Thanks Jason for your reply,

          I know that with MD3000i there are dual controller (SPo an SP1) with two Ethernet ports on each (total 4 cables go in/out from this unit) but cmiiw, only one controller can operate at the same time while the other is just a failover / standby. From the active SP, two can work simultaneously for two different iSCSI session into the LUNs hosted inside the SAN.

          at the moment four cable is running with each own subnet.

          so at least in the configuration I shall create two subnet for each SAN ?

          Comment


          • #6
            Re: Installing iSCSI SAN on existing iSCSI SAN Network

            Originally posted by Albertwt View Post
            Thanks Jason for your reply,

            I know that with MD3000i there are dual controller (SPo an SP1) with two Ethernet ports on each (total 4 cables go in/out from this unit) but cmiiw, only one controller can operate at the same time while the other is just a failover / standby. From the active SP, two can work simultaneously for two different iSCSI session into the LUNs hosted inside the SAN.

            at the moment four cable is running with each own subnet.

            so at least in the configuration I shall create two subnet for each SAN ?
            Hi Albert,

            Depending on the amount of pNICS you have in each physical host will help determine the setup and also what your network throughput requirements are. If each host has 2 pNICS the configuration could look like this:

            SUBNET # 1 (IP's are only given as an example)

            ESX01 - 192.168.100.21 (VMKernel Port - IPStorage-1)
            ESX02 - 192.168.100.22 (VMKernel Port - IPStorage-1)
            ESX03 - 192.168.100.23 (VMKernel Port - IPStorage-1)
            SAN 1 Controller 0 Port 0 - 192.168.100.11
            SAN 1 Controller 1 Port 0 - 192.168.100.12
            SAN 2 Controller 0 Port 0 - 192.168.100.13
            SAN 2 Controller 1 Port 0 - 192.168.100.14

            SUBNET # 2 (IP's are only give as an example)

            ESX01 - 192.168.101.21 (VMKernel Port - IPStorage-2)
            ESX02 - 192.168.101.22 (VMKernel Port - IPStorage-2)
            ESX03 - 192.168.101.23 (VMKernel Port - IPStorage-2)
            SAN 1 Controller 0 Port 1 - 192.168.101.11
            SAN 1 Controller 1 Port 1 - 192.168.101.12
            SAN 2 Controller 0 Port 1 - 192.168.101.13
            SAN 2 Controller 1 Port 1 - 192.168.101.14

            This configuration will allow all hosts to communicate with both SAN's and any LUN's that are assigned.

            If you had 4 pNICS per server you could expand out the IP scheme to add an additional two subnets, configuring each SAN with its own dedicated network and an increase in total throughput.

            Following the steps in the Dell document will walk you through the configuration of how to setup the MDS and your ESX hosts for Round Robin Multipathing which will allow for better multi-pathing/load balancing.

            -Jason
            MCSA/MCSE 2K3,MCITP:ESA,MCTS x 4,VCP x 2

            Comment


            • #7
              Re: Installing iSCSI SAN on existing iSCSI SAN Network

              what I'm going to do is to assign each blue cable IP address 192.168.1.0/24 so all of those blue cable is all in the same subnet.

              another question is that would there be any significant data backup effect if somehow I add more pNIC into the ESXI host (more green cable going into the ESXi hosts), so in the LAN vSwitch i add 4 uplinks port for access to my LAN.

              adding some more blue cable into my SAN host will not going to help since this MD3000i is just pure / basic SAN so it can only uses one controller active path while the other is fail-over.

              thanks for your reply.

              Comment


              • #8
                Re: Installing iSCSI SAN on existing iSCSI SAN Network

                Originally posted by Albertwt View Post
                what I'm going to do is to assign each blue cable IP address 192.168.1.0/24 so all of those blue cable is all in the same subnet.
                Just for my two cents, I would follow what is outlined in the best practice guide and use two seperate subnets.

                Originally posted by Albertwt View Post
                another question is that would there be any significant data backup effect if somehow I add more pNIC into the ESXI host (more green cable going into the ESXi hosts), so in the LAN vSwitch i add 4 uplinks port for access to my LAN.
                Depending on your current utilziation you could see a benefit or you might not see a change at all. When running your backups monitor the uplink either via vCenter or network monitoring tools to see if you are saturating the single link. If so an additional interface maybe needed.


                Originally posted by Albertwt View Post
                adding some more blue cable into my SAN host will not going to help since this MD3000i is just pure / basic SAN so it can only uses one controller active path while the other is fail-over.
                As I am not all that familiar with your SAN unit I will defer to the best practice guide again. In there it states the following:

                The Dell PowerVault MD3000i array comprises two active RAID controllers. However, at any given time only one RAID controller owns a virtual disk or logical unit (LUN). Each RAID controller has two GbE ports for iSCSI data traffic. By configuring controller 0, port 0 and controller 1, port 0 in one IP subnet and controller 0, port 1 and controller 1, port 1 in another IP subnet, both traffic isolation across physical Ethernet segments (using redundant Ethernet switches) and path redundancy can be achieved.

                Even though only one SP can "own" a give LUN at a time you are still going to achieve better perfromance and availability in your environment.

                Also, you may want to take a look at this THREAD. Chad Sakac works for EMC and is there EMC/VMware guru. However that post was compiled by multiple vendors (Dell, EMC, NetApp, HP Lefthand, etc) about using iSCSI with vSphere. It is a very good read. The following Podcast ties directly to the post as well.

                -Jason
                Last edited by VWA4; 31st May 2010, 07:47.
                MCSA/MCSE 2K3,MCITP:ESA,MCTS x 4,VCP x 2

                Comment


                • #9
                  Re: Installing iSCSI SAN on existing iSCSI SAN Network

                  ah yes,

                  thanks for the deep explanation Jason, I really appreciated and learn something new here

                  I'll assign one controller one subnet as per your suggestion.

                  cmiiw since there are two SAN and each having two controller, therefore four subnets are needed ?

                  Comment


                  • #10
                    Re: Installing iSCSI SAN on existing iSCSI SAN Network

                    Originally posted by Albertwt View Post
                    cmiiw since there are two SAN and each having two controller, therefore four subnets are needed ?
                    If going that route you would need four pNICS on each host, but alot would also depend on your usage as well. I would suggest running some performance counters/numbers to see how much data you are driving to each unit. Then deciding on if you need to scale out with additional interfaces.

                    -Jason
                    MCSA/MCSE 2K3,MCITP:ESA,MCTS x 4,VCP x 2

                    Comment


                    • #11
                      Re: Installing iSCSI SAN on existing iSCSI SAN Network

                      yes, you're right Jason,

                      in my diagram it seems that i put two uplinks cable from all of the ESXi hosts, i think that is too much, therefore I'll put only one cable which provides uplink to my production network while two cables going into the switch for greater throughput. (rather than one single cable into each switch).

                      I'll redesign the diagram and post the final deployment plan here.

                      Comment


                      • #12
                        Re: Installing iSCSI SAN on existing iSCSI SAN Network

                        Originally posted by Albertwt View Post
                        yes, you're right Jason,

                        in my diagram it seems that i put two uplinks cable from all of the ESXi hosts, i think that is too much, therefore I'll put only one cable which provides uplink to my production network while two cables going into the switch for greater throughput. (rather than one single cable into each switch).

                        I'll redesign the diagram and post the final deployment plan here.
                        Albertwt,

                        Not sure if it is possible in your situation, but if you can or get there at some point in the future I would add an additional NIC to your production uplink to allow for redundancy in case of a failure (plus I am assuming you are running the ESXi management interface over that lone uplink)

                        -Jason
                        MCSA/MCSE 2K3,MCITP:ESA,MCTS x 4,VCP x 2

                        Comment


                        • #13
                          Re: Installing iSCSI SAN on existing iSCSI SAN Network

                          hm... yes Jason, you're right

                          I'd need additional NIC then for this case, because at the moment the cable from the R710 is only one for each switch while each SAN got two cable connected to each switch.

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