6 Replies Latest reply: Aug 17, 2012 3:50 PM by mdaskalov RSS

    RAC interconnect

    user8897201
      Hi guys,

      I've this doubt since I'm using Oracle RAC... Oracle recommends the use of a dedicated swith to the RAC servers communication. We are talking about using a dedicated switch to the heartbeat mechanism or to allowing one RAC node to read data blocks from another RAC node's cache via the Interconnect?

      Thanks.
      A.
        • 1. Re: RAC interconnect
          onedbguru
          user8897201 wrote:
          Hi guys,

          I've this doubt since I'm using Oracle RAC... Oracle recommends the use of a dedicated swith to the RAC servers communication. We are talking about using a dedicated switch to the heartbeat mechanism or to allowing one RAC node to read data blocks from another RAC node's cache via the Interconnect?
          That is correct. The reason for the dedicated switch is to isolate the interconnect from any potential network storm that could so severely cripple your network as to cause delays in the heartbeat checkin that it thinks that one or more nodes have disappeared causing node evictions. I have seen this happen on more than one occasion. therefore, follow the recommendation to mitigate any potential problems.
          Thanks.
          A.
          • 2. Re: RAC interconnect
            user8897201
            thanks.

            But should also be used to the cache fusion mechanism, rigth?
            • 3. Re: RAC interconnect
              RaeK
              user8897201 wrote:
              thanks.

              But should also be used to the cache fusion mechanism, rigth?
              That is correct.

              For more detail you may refer to 9i documentation at http://docs.oracle.com/cd/B10500_01/rac.920/a96597/pslkgdtl.htm
              • 4. Re: RAC interconnect
                krishan Jaglan
                Hi User8897201,

                as far as i know, Interconnect and heartbeat goes over same link( there is no way to separate them out). If you have Big switch and/Or don't want a physical switch just of RAC , you can ask your Network Administrator to create VLAN for (Interconnect ) - Its same as dedicated switch as RAC traffic will no interrupted by flooded network by anything else.

                Key is Network must be dedicated for Interconnect( Non Shared Network), how you achieve doesn't mattter ( either dedicated switch or VLAN just for Interconnect).

                Hope it helps you.

                Thanks
                krishan Jaglan
                • 5. Re: RAC interconnect
                  onedbguru
                  krishan Jaglan wrote:
                  Hi User8897201,

                  as far as i know, Interconnect and heartbeat goes over same link( there is no way to separate them out). If you have Big switch and/Or don't want a physical switch just of RAC , you can ask your Network Administrator to create VLAN for (Interconnect ) - Its same as dedicated switch as RAC traffic will no interrupted by flooded network by anything else.

                  Key is Network must be dedicated for Interconnect( Non Shared Network), how you achieve doesn't mattter ( either dedicated switch or VLAN just for Interconnect).
                  Again, I have seen a switch that uses a VLAN get saturated to the point that one or more nodes from a cluster rebooted. A switch - even a director-class switch only has so much bandwidth - which if not dedicated to cluster interconnect can still get overwhelmed causing node evictions. Been there, done that, switched to dedicated and then got the T-Shirt.

                  >
                  Hope it helps you.

                  Thanks
                  krishan Jaglan
                  • 6. Re: RAC interconnect
                    mdaskalov
                    The interconnect interface is used for both tasks (by default).

                    You could have multiple interconnect physical interfaces in which case depending on your switch characteristics you can use only one switch and connect multiple interfaces (all used for interconnect traffice) - this is single switch link aggregation scheme (or starting with Oracle 11.2.0.2 the GI can manage those interfaces).

                    Eventually you could use 2 switches link aggregation (to assure you have no single point of failure) where interconnect physical interfaces are active/passive.


                    Regards,
                    Mihail