3 Replies Latest reply: Aug 8, 2012 1:59 AM by Chrisjenkins-Oracle RSS

    Replication across datacenter

      Hi :
      I've a requirement of replication involving timesten instance spread across two datacenter( DS1 and DS2).
      First Datacenter (DS1) has internal replication involving 6 Timesten instance. The data from DS1 needs to be replicated to the 15 timesten instance in second datacenter (DS2).
      This will be a unidirection replication...from DS1 and DS2.

      I'm thinking of using propagation for replicating between DS1 and DS2.I've 2 reason for this:
           1)Replication to many subscribers can effect the replication latency. Our application requirement requires this latency to be as low as possible.
           2)We cannot open multiple ports between the 2 datacenter.
      In totality, i would have 3 replication schemes.
      R1           - for replication among timesten instance in first datacenter (DS1).
      DS1_TO_DS2 - for propagating replication from first datacenter (DS1) to second datacenter(DS2).
      R3          - for replication among timesten instance in second datacenter(DS2).

      Refer the below diagram for pictorial explanation of the replication.
                     First Datacenter(DS1)          |                    Second Datacenter(DS2)

      MASTER(T1) --> PROPAGATOR(T6)------------------> SUBSCRIBER(T15) ----> SUBSCRIBER(T1)

      The above replication works fine till the timesten intance (T15) in second datacenter. But replication fails beyond that.
      After going through the document throughly i found out that,we cannot have a hierarchy of propagators where propagators forward updates to other propagators.

      So my question to all the gurus is how do i accomplish this replication architecture fullfilling the above reason.


      Edited by: user9502771 on Aug 6, 2012 10:12 AM
        • 1. Re: Replication across datacenter
          I'm afraid that the short answer is that you can't.

          There are variosu possibilities but all have their disadvantages. If you really (a) cannot open multipel ports in the firewall and (b0 have bandwidth/latency limitations on the link between the datacenters then my best suggestion is to go with your current setup as far as SUBSCRIBER (T15) and write a custom XLA program that runs on T15, captures all the changes that arrive there via replication from T6 and either (a) does it's own propagation to the other datastores in DS2 or (b) use T15 as purely the receiving point for replication from DS1 and the XLA program then inserts into one of a set of replicated TT in second DS.

          Option (a):
          |--- XLA --> SUBSCRIBER (T1)
          MASTERS(T1,...) --- TT rep --> PROPAGATOR(T6) ---------- TT rep -----------> SUBSCRIBER(T15) -- XLA ---> SUBSCRIBER(T2)
          |--- XLA --> SUBSCRIBER (T3)
          | ...

          Option (b):

          |----- TT rep --> SUBSCRIBER (T2)
          MASTERS(T1,...) --- TT rep --> PROPAGATOR(T6) ---------- TT rep -----------> SUBSCRIBER(T15) -- XLA ---> SUBSCRIBERS(T1) --- TT rep --> SUBSCRIBER(T3)
          |----- TT rep --> SUBSCRIBER (T4)

          I'm not sure my diagrams are very good but hopefully you get the idea.

          • 2. Re: Replication across datacenter
            Thanks Chris. I was thinking of the same solution.

            One thing though is not clear to me is as how we can have HA in non active-standby replication configuration.

            • 3. Re: Replication across datacenter
              I don't quite understand the question. Can you please explain in more detail and in particular clarify what you mean by High Availability in this context.