Load Balancing and Asynchronous Multimaster Replication

We are planning a new project with 2 server lines for load balancing reasons. We also plan to use sessions being valid for 30 minutes. Each of the 2 server lines has its own Oracle database (identical tables) for the transactions. Within one session the load balancing sends the user always to the same server line.
Independant transactions are executed on both server lines.
Is Asynchronous Multimaster Replication the adequate solution to have the two databases synchronized, what has to be considered (network, memory, cpu) or what else can (has to) be used ?
We want to avoid a RAC solution because of the high costs.

The two options that come to mind here are asynchronous multimaster replication and Oracle Streams.
- What version of the Oracle database will you be using?
- What sort of transaction volume do you anticipate? How much redo generation?
- What sort of connection exists between the two machines?
- Is there an upper limit on the time that can be taken to replicate a transaction from one machine to the other?
Justin
Distributed Database Consulting, Inc.
http://www.ddbcinc.com/askDDBC

Similar Messages

Load Balancing and Failover with 10G Standard Edition

Hi,
I am new to Oracle Replication and need some help setting up replication for load balancing and failover. Is this possible using Oracle 10G Standard Edition? I plan on having all updates done on the master site and both databases will be for reads. In case of failure of the master site, I would need to be able to failover to the other database.
Also, if anyone knows of any documention for Basic Replication in 10G, please let me know.
Thanks.

Simple nnapshot replication of data would require significant manual effort to configure to load balance or failover. One the load balancing side, you would generally be limited to to static load balancing-- assigning half the users to one machine and the other half of the users to the other machine, regardless of who is actively using the machine. Failover would be a significant manual effort, particularly to bring the failed machine back into the cluster. You would be implementing the guts of multi-master replication.
Frankly, if you actually have a system which is valuable enough to need load balancing and disaster recovery, I'm going to wager that it will be far cheaper even in the short run to buy more boxes and/or enterprise edition licenses than to try to implement this sort of thing yourself. In the long run, it will be far cheaper, since it will be far easier to maintain. Building all this yourself would probably be penny wise and pound foolish.
Justin
Distributed Database Consulting, Inc.
http://www.ddbcinc.com/askDDBC

3rd party distributed SW load balancing with In-Memory Replication

          Hi,
          Could someone please comment on the feasibility of the following setup?
          I've started testing replication with a software load balancing product. This
          product lets all nodes receive all packets and uses a kernel-level filter
          to let only one node at the time receive it. Since there's minimum 1 heartbeat
          between the nodes, there are several NICs in each node.
          At the moment it seems like it doesn't work: - I use the SessionServlet - with
          a 2-node cluster I first have the 2 nodes up and I access it with a single client:
          .the LB is configured to be sticky wrt. source IP address, so the same node gets
          all the traffic - when I stop the node receiving the traffic the other node takes
          over (I changed the colours of SessionServlet) . however, the counter restarts
          at zero
          From what I read of the in-memory replication documentation I thought that it
          might work also with a distributed software load balancing cluster. Any comments
          on the feasability of this?
          Is there a way to debug replication (in WLS6SP1)? I don't see any replication
          messages in the logs, so I'm not even sure that it works at all. - I do get a
          message about "Clustering Services startting" when I start the examples server
          on each node - is there anything tto look for in the console to make sure that
          things are working? - the evaluation license for WLS6SP1 on NT seems to support
          In-Memory Replication and Cluster. However, I've also seen a Cluster-II somewhere:
          is that needed?
          Thanks for your attention!
          Regards, Frank Olsen


We are considering Resonate as one of the software load balancer. We haven't certified
          them yet. I have no idea how long its going to take.
          As a base rule if the SWLB can do the load balancing and maintain stickyness that is fine
          with us as long as it doesn't modify the cookie or the URL if URL rewriting is enabled.
          Having said that if you run into problems we won't be able to support you since it is not
          certified.
          -- Prasad
          Frank Olsen wrote:
          > Prasad Peddada <[email protected]> wrote:
          > >Frank Olsen wrote:
          > >
          > >> Hi,
          > >>
          > > We don't support any 3rd party software load balancers.
          >
          > Does that mean that there are technical reasones why it won't work, or just that
          > you haven't tested it?
          >
          > > As >I said before I am thinking your configuration is >incorrect if n-memory
          > replication is not working. I would >strongly suggest you look at webapp deployment
          > descriptor and >then the config.xml file.
          >
          > OK.
          >
          > >Also doing sticky based on source ip address is not good. You >should do it based
          > on passive cookie persistence or active >cookie persistence (with cookie insert,
          > a new one).
          > >
          >
          > I agree that various source-based sticky options (IP, port; network) are not the
          > best solution. In our current implementation we can't do this because the SW load
          > balancer is based on filtering IP packets on the driver level.
          >
          > Currently I'm more interested in understanding whether it can our SW load balancer
          > can work with your replication at all?
          >
          > What makes me think that it could work is that in WLS6.0 a session failed over
          > to any cluster node can recover the replicated session.
          >
          > Can there be a problem with the cookies?
          > - are the P/S for replication put in the cookie by the node itself or by the proxy/HW
          > load balancer?
          >
          > >
          > >The options are -Dweblogic.debug.DebugReplication=true and
          > >-Dweblogic.debug.DebugReplicationDetails=true
          > >
          >
          > Great, thanks!
          >
          > Regards,
          > Frank Olsen

WLS6.1sp1 stateful EJB problem = load-balancing and fail over

          I have three problem
          1. I have 2 clustered server. my weblogic-ejb-jar.xml is here
          <?xml version="1.0"?>
          <!DOCTYPE weblogic-ejb-jar PUBLIC '-//BEA Systems, Inc.//DTD WebLogic 6.0.0 EJB//EN'
          'http://www.bea.com/servers/wls600/dtd/weblogic-ejb-jar.dtd'>
          <weblogic-ejb-jar>
          <weblogic-enterprise-bean>
               <ejb-name>DBStatefulEJB</ejb-name>
               <stateful-session-descriptor>
               <stateful-session-cache>
                    <max-beans-in-cache>100</max-beans-in-cache>
                    <idle-timeout-seconds>120</idle-timeout-seconds>
               </stateful-session-cache>
               <stateful-session-clustering>
                    <home-is-clusterable>true</home-is-clusterable>
                    <home-load-algorithm>RoundRobin</home-load-algorithm>
                    <home-call-router-class-name>common.QARouter</home-call-router-class-name>
                    <replication-type>InMemory</replication-type>
               </stateful-session-clustering>
               </stateful-session-descriptor>
               <jndi-name>com.daou.EJBS.solutions.DBStatefulBean</jndi-name>
          </weblogic-enterprise-bean>
          </weblogic-ejb-jar>
          when i use "<home-call-router-class-name>common.QARouter</home-call-router-class-name>"
          and deploy this ejb, exception cause
          <Warning> <Dispatcher> <RuntimeException thrown b
          y rmi server: 'weblogic.rmi.cluster.ReplicaAwareServerRef@9 - jvmid: '2903098842
          594628659S:203.231.15.167:[5001,5001,5002,5002,5001,5002,-1]:mydomain:cluster1',
          oid: '9', implementation: 'weblogic.jndi.internal.RootNamingNode@5f39bc''
          java.lang.IllegalArgumentException: Failed to instantiate weblogic.rmi.cluster.B
          asicReplicaHandler due to java.lang.reflect.InvocationTargetException
          at weblogic.rmi.cluster.ReplicaAwareInfo.instantiate(ReplicaAwareInfo.ja
          va:185)
          at weblogic.rmi.cluster.ReplicaAwareInfo.getReplicaHandler(ReplicaAwareI
          nfo.java:105)
          at weblogic.rmi.cluster.ReplicaAwareRemoteRef.initialize(ReplicaAwareRem
          oteRef.java:79)
          at weblogic.rmi.cluster.ClusterableRemoteRef.initialize(ClusterableRemot
          eRef.java:28)
          at weblogic.rmi.cluster.ClusterableRemoteObject.initializeRef(Clusterabl
          eRemoteObject.java:255)
          at weblogic.rmi.cluster.ClusterableRemoteObject.onBind(ClusterableRemote
          Object.java:149)
          at weblogic.jndi.internal.BasicNamingNode.rebindHere(BasicNamingNode.jav
          a:392)
          at weblogic.jndi.internal.ServerNamingNode.rebindHere(ServerNamingNode.j
          ava:142)
          at weblogic.jndi.internal.BasicNamingNode.rebind(BasicNamingNode.java:36
          2)
          at weblogic.jndi.internal.BasicNamingNode.rebind(BasicNamingNode.java:36
          9)
          at weblogic.jndi.internal.BasicNamingNode.rebind(BasicNamingNode.java:36
          9)
          at weblogic.jndi.internal.BasicNamingNode.rebind(BasicNamingNode.java:36
          9)
          at weblogic.jndi.internal.BasicNamingNode.rebind(BasicNamingNode.java:36
          9)
          at weblogic.jndi.internal.RootNamingNode_WLSkel.invoke(Unknown Source)
          at weblogic.rmi.internal.BasicServerRef.invoke(BasicServerRef.java:296)
          So do i must use it or not???
          2. When i don't use "<home-call-router-class-name>common.QARouter</home-call-router-class-name>"
          , there's no exception
          but load balancing does not happen. According to the document , there's must load
          balancing when i call home.create() method.
          my client program goes here
               DBStateful the_ejb1 = (DBStateful) PortableRemoteObject.narrow(home.create(),
          DBStateful.class);
               DBStateful the_ejb2 = (DBStateful) PortableRemoteObject.narrow(home.create(3),
          DBStateful.class);
          the result is like that
               the_ejb1 = ClusterableRemoteRef(203.231.15.167 weblogic.rmi.cluster.PrimarySecon
               daryReplicaHandler@4695a6)/397
               the_ejb2 = ClusterableRemoteRef(203.231.15.167 weblogic.rmi.cluster.PrimarySecon
               daryReplicaHandler@acf6e)/398
               or
               the_ejb1 = ClusterableRemoteRef(203.231.15.125 weblogic.rmi.cluster.PrimarySecon
               daryReplicaHandler@252fdf)/380
               the_ejb2 = ClusterableRemoteRef(203.231.15.125 weblogic.rmi.cluster.PrimarySecon
               daryReplicaHandler@6a0252)/381
               I think the result should be like under one... isn't it??
               the_ejb1 = ClusterableRemoteRef(203.231.15.167 weblogic.rmi.cluster.PrimarySecon
               daryReplicaHandler@4695a6)/397
               the_ejb2 = ClusterableRemoteRef(203.231.15.125 weblogic.rmi.cluster.PrimarySecon
               daryReplicaHandler@6a0252)/381
          In this case i think the_ejb1 and the_ejb2 must have instance in different cluster
          server
          but they go to one server .
          3. If i don't use      "<home-call-router-class-name>common.QARouter</home-call-router-class-name>",
          "<replication-type>InMemory</replication-type>" then load balancing happen but
          there's no fail-over
          So how can i get load-balancing and fail over together??


          I have three problem
          1. I have 2 clustered server. my weblogic-ejb-jar.xml is here
          <?xml version="1.0"?>
          <!DOCTYPE weblogic-ejb-jar PUBLIC '-//BEA Systems, Inc.//DTD WebLogic 6.0.0 EJB//EN'
          'http://www.bea.com/servers/wls600/dtd/weblogic-ejb-jar.dtd'>
          <weblogic-ejb-jar>
          <weblogic-enterprise-bean>
               <ejb-name>DBStatefulEJB</ejb-name>
               <stateful-session-descriptor>
               <stateful-session-cache>
                    <max-beans-in-cache>100</max-beans-in-cache>
                    <idle-timeout-seconds>120</idle-timeout-seconds>
               </stateful-session-cache>
               <stateful-session-clustering>
                    <home-is-clusterable>true</home-is-clusterable>
                    <home-load-algorithm>RoundRobin</home-load-algorithm>
                    <home-call-router-class-name>common.QARouter</home-call-router-class-name>
                    <replication-type>InMemory</replication-type>
               </stateful-session-clustering>
               </stateful-session-descriptor>
               <jndi-name>com.daou.EJBS.solutions.DBStatefulBean</jndi-name>
          </weblogic-enterprise-bean>
          </weblogic-ejb-jar>
          when i use "<home-call-router-class-name>common.QARouter</home-call-router-class-name>"
          and deploy this ejb, exception cause
          <Warning> <Dispatcher> <RuntimeException thrown b
          y rmi server: 'weblogic.rmi.cluster.ReplicaAwareServerRef@9 - jvmid: '2903098842
          594628659S:203.231.15.167:[5001,5001,5002,5002,5001,5002,-1]:mydomain:cluster1',
          oid: '9', implementation: 'weblogic.jndi.internal.RootNamingNode@5f39bc''
          java.lang.IllegalArgumentException: Failed to instantiate weblogic.rmi.cluster.B
          asicReplicaHandler due to java.lang.reflect.InvocationTargetException
          at weblogic.rmi.cluster.ReplicaAwareInfo.instantiate(ReplicaAwareInfo.ja
          va:185)
          at weblogic.rmi.cluster.ReplicaAwareInfo.getReplicaHandler(ReplicaAwareI
          nfo.java:105)
          at weblogic.rmi.cluster.ReplicaAwareRemoteRef.initialize(ReplicaAwareRem
          oteRef.java:79)
          at weblogic.rmi.cluster.ClusterableRemoteRef.initialize(ClusterableRemot
          eRef.java:28)
          at weblogic.rmi.cluster.ClusterableRemoteObject.initializeRef(Clusterabl
          eRemoteObject.java:255)
          at weblogic.rmi.cluster.ClusterableRemoteObject.onBind(ClusterableRemote
          Object.java:149)
          at weblogic.jndi.internal.BasicNamingNode.rebindHere(BasicNamingNode.jav
          a:392)
          at weblogic.jndi.internal.ServerNamingNode.rebindHere(ServerNamingNode.j
          ava:142)
          at weblogic.jndi.internal.BasicNamingNode.rebind(BasicNamingNode.java:36
          2)
          at weblogic.jndi.internal.BasicNamingNode.rebind(BasicNamingNode.java:36
          9)
          at weblogic.jndi.internal.BasicNamingNode.rebind(BasicNamingNode.java:36
          9)
          at weblogic.jndi.internal.BasicNamingNode.rebind(BasicNamingNode.java:36
          9)
          at weblogic.jndi.internal.BasicNamingNode.rebind(BasicNamingNode.java:36
          9)
          at weblogic.jndi.internal.RootNamingNode_WLSkel.invoke(Unknown Source)
          at weblogic.rmi.internal.BasicServerRef.invoke(BasicServerRef.java:296)
          So do i must use it or not???
          2. When i don't use "<home-call-router-class-name>common.QARouter</home-call-router-class-name>"
          , there's no exception
          but load balancing does not happen. According to the document , there's must load
          balancing when i call home.create() method.
          my client program goes here
               DBStateful the_ejb1 = (DBStateful) PortableRemoteObject.narrow(home.create(),
          DBStateful.class);
               DBStateful the_ejb2 = (DBStateful) PortableRemoteObject.narrow(home.create(3),
          DBStateful.class);
          the result is like that
               the_ejb1 = ClusterableRemoteRef(203.231.15.167 weblogic.rmi.cluster.PrimarySecon
               daryReplicaHandler@4695a6)/397
               the_ejb2 = ClusterableRemoteRef(203.231.15.167 weblogic.rmi.cluster.PrimarySecon
               daryReplicaHandler@acf6e)/398
               or
               the_ejb1 = ClusterableRemoteRef(203.231.15.125 weblogic.rmi.cluster.PrimarySecon
               daryReplicaHandler@252fdf)/380
               the_ejb2 = ClusterableRemoteRef(203.231.15.125 weblogic.rmi.cluster.PrimarySecon
               daryReplicaHandler@6a0252)/381
               I think the result should be like under one... isn't it??
               the_ejb1 = ClusterableRemoteRef(203.231.15.167 weblogic.rmi.cluster.PrimarySecon
               daryReplicaHandler@4695a6)/397
               the_ejb2 = ClusterableRemoteRef(203.231.15.125 weblogic.rmi.cluster.PrimarySecon
               daryReplicaHandler@6a0252)/381
          In this case i think the_ejb1 and the_ejb2 must have instance in different cluster
          server
          but they go to one server .
          3. If i don't use      "<home-call-router-class-name>common.QARouter</home-call-router-class-name>",
          "<replication-type>InMemory</replication-type>" then load balancing happen but
          there's no fail-over
          So how can i get load-balancing and fail over together??

Load Balancing and WLS primary server offset

I've got a load balancer in front of my WLS cluster, and I'm trying to
          set up load balancing based on WLS clustering. What I need to know to
          do this is the offset within the cookie that's responsible for
          determining which machine within the cluster to direct to.
          Any idea how I can get this information?
          thanks,
          cfraser


Chris Fraser wrote:
          > The proxy/plug-in solution sounds pretty cool, but I've got a high speed
          > Alteon Load Balancer already set up. I would prefer to use that as the load
          > balancer to the WL cluster rather than pay to bring another WLS online to do
          > pretty much what the load balancer, that I already own, can do. I know that
          > going this route means that we're probably not going to be able to do things
          > like failover to the secondary when the primary dies, but we will be able to
          > load balance and also have the ability to dynamically add/delete servers
          > from the list of available servers as they are brought up/down.
          In Memory session replication doesn't work without our plugins. I will have to
          do little bit of investigation to figure out if other persistence mechanism's
          would work without our plugins if you are interested in them. I have to remind
          you though that other types of persistence mechanism's we support are slower
          compared to in memory session replication.
          > Are there any plans to work with an Alteon or a Foundry to have their Load
          > Balancers act as the front end to a WLS cluster?
          Currently none. We are taking steps to make the plugin's and cluster more
          robust, we currently don't have any plans to work with other 3rd party vendors.
          > For us it would be ideal, because we wouldn't have to support another piece of
          > software, we would just
          > have to support the hardware based Alteon, which can handle thousands of
          > transactions per second.
          > I understand that the primary and secondary server information is available
          > in the sessionID, I'm just not quite sure how to extract it.
          This information is saved in the cookie. But I wouldn't count that, as we
          have plans to change this. I cannot give your more details.
          > Is there a particular offset within the session ID where it can always be
          > found?
          I don't quite get what you mean here.
          Hope this helps.
          - Prasad
          > thanks for the help,
          > cfraser
          > ----------
          > C h r i s t o p h e r A . F r a s e r
          > Director, Technology
          > macroplay.com, Inc.
          > [email protected]
          >
          > Viresh Garg wrote:
          >
          > > You should be using
          > > -- NES +NSAPI Plugin
          > > -- IIS + ISAPI Plugin
          > > -- WEblogic server acting as proxy
          > > -- Apache +Apache Plugin ( only in Denali)
          > >
          > > front-ending your Weblogic cluster
          > >
          > > These proxies/plug-ins are smart to do a lot of things like:
          > >
          > > -- Load balancing in weblogic cluster
          > > -- Adding/deleting servers dynamically in cluster when the servers
          > > join/leave Weblogic cluster
          > > -- failover to secondary when primary dies.
          > >
          > > As far as the information about primary and secondary is concerned it is
          > > available in session ID.
          > >
          > > --Viresh Garg
          > >
          > > Chris Fraser wrote:
          > >
          > > > I've got a load balancer in front of my WLS cluster, and I'm trying to
          > > > set up load balancing based on WLS clustering. What I need to know to
          > > > do this is the offset within the cookie that's responsible for
          > > > determining which machine within the cluster to direct to.
          > > >
          > > > Any idea how I can get this information?
          > > >
          > > > thanks,
          > > > cfraser

Which cluster attribute should you modify to ensure that load balancing and

An EJB is targeted to a cluster. Remote EJB clients can therefore take advantage of WebLogic Server’s load balancing and failover capabilities.
However, a proxy server exists between the clients and cluster, which performs IP address transaction.
Which cluster attribute should you modify to ensure that load balancing and failover work correctly?
A. Multicast Address
B. Persistent Store
C. Cluster Address
D. Migration Basis
E. Replication Channel

http://docs.oracle.com/cd/E13222_01/wls/docs81/config_xml/Cluster.html
Cluster address

VPN load balancing and ASA !!!

Hi netpros,
I have a couple of questions about this and hope you might be able to assist me.
1.- Are VPN load balancing and failover (Active/Active) mutually exclusive ..? I mean they can't be used at the same time correct ..?
2.- How does the ASA handle the return traffic from the Internal LAN towards the remote client .. Because the cluster only requires ONE public virtual IP address, which will work for incoming packets .. but what about the return traffic which has knowledge of the DHCP scope's default gateway IP address only .. ? How gets the returned packet redirected from the default gateway IP address to the respective ASA internal IP address .?
3.- VPN load balancing only applies to remote clients using easy VPN technology (easy vpn client, hardware client , pIX using easy vpn client etc ) and does not work with static LAN-LAN tunnel .. correct ..?
Your comments are much appreciated

Hi Gilbert ..
1.- Thanks I wanted to make sure.
2.- I know that .. my question is in regards the return packets .. for example if I have the below IP schema:
ASA1: Public 20.20.20.20
Private 192.168.1.1
ASA2: Public 20.20.20.21
Private 192.168.1.2
Cluster virutal IP: 20.20.20.10
Default gateway for segment 192.168.1.0 is 192.168.1.1
Let's say that a vpn client tries to connect and the cluster instructs the client to connect to ASA2 20.20.20.21. The packets reach the internal server at 192.168.1.100. The internal server then sends the return packets back to the client by forwarding them to its default gateway which is 192.168.1.1 (ASA1). Here is my question .. how does the cluster handles this because the return packet are supposed to be directed to ASA2 192.168.1.2
3.- Any idea about this one ..?
Cheers,

Load balancing and rfc metadata repository in reciever rfc communication ch

hi.
i want to know the purpose of load balancing and rfc meta data repository in RFC communication channel.
and can u send me any examples on this load balancing.
waiting for your response.
bye.
regards.
seeta ram.

Hi Seeta Ram,
Load distribution is handled by the message server (there is one message server in an SAP System). When a user logs on, the message server assigns him or her to the application server that currently has the <b>smallest load</b>.
Well now you can understand that we use load balancing for better performance by distributing the work to different processes to balance or maintain the work load in SAP system.
For more information refer to this link
http://help.sap.com/saphelp_nw04/helpdata/en/28/75153a1a5b4c2de10000000a114084/content.htm
Regards
Sumit Bhutani

Advantages of using a webserver inbetween a load balancer and application servers

I am building out a new weblogic domain.
I am wondering which one of these configuration to go with:
1. Load balancer > weblogic servers
2. Load balancer > web server > weblogic servers
Could someone tell me what are the specific advantages of having web servers inbetween a load balancer and application servers (besides caching static data content and acting as a proxy)?
Thanks in advance
Srini

Other than hosting the static content, nothing much really. We have our load balancer go straight to WL for applications without static content and route to web server if there is static content. Easy enough to do it both ways, best of both worlds.

For a true load balancing and high-availability OHS, OPMN, and mod_oc4j

i have read this link of Enabling Clustering on oc4j9.0.4 standalone app server
http://www.oracle.com/technology/docs/tech/java/oc4j/htdocs/getstart.htm#1015479
To test the clustering, start up the load balancer by executing "java -jar loadbalancer.jar".
C:\OC4J_EXTENDED\j2ee\home>java -jar loadbalancer.jar
In a future release of Oracle Application Server, loadbalancer.jar will be
desupported. Because of this, we strongly suggest that you discontinue your use
of loadbalancer.jar in this release. Under high loads, loadbalancer.jar may not
function properly. For a true load balancing and high-availability solution,
please move to use OHS, OPMN, and mod_OC4J. For more information, please see
http://otn.oracle.com/products/ias/ohs/content.html
Balancer initialized...
what load balancer should i use for web clustering
<frontend host="balancer-host" port="balancer-port" />
balancer-host=localhost
balancer-port=80
for all nodes i mentioned same host and port in http-web-site.xml.Is it correct?
i completed all the steps and run http://localhost:6666/session/SessionServlet
i hit 3 times
in the different browser http://localhost:7777/session/SessionServlet
instead of coming 4 it starting from 1 only.

can i use this loadbalancer.jar or not?
how to mod_oc4j in standalone app server

Load balancing and High Availability topology

Our Forms 6i client-server application currently runs on Citrix farm of 20 Windows 2000 boxes (IBM Blade Servers 2 CPU and 2 Gig Memory).
Application supports 2000 users.
We are moving to AS 10g r2, forms 10g and the goal is to use same hardware, 20 Windows boxes (or less), for intranet web deployment.
What will be our best choices for application Load balancing and High Availability?
Hardware load balancer, Web Cache, mod-oc4j? Combinations?
Any suggestions, best practices, your experience?

Gerd, I understand, that you are running 10g web forms through the browser, but using Citrix for deployment. This means that in addition to Application Server and Forms runtime sessions, it will be separate browser session opened for each user. What the advantage of this configuration?
Michael, we are aware, that Citrix is not supported by Oracle as a deployment platform. That only means that prior contacting Oracle Support we have to reproduce the problem in standard environment. It was never been a problem to reproduce problem :) We were using Citrix as a deployment platform for Forms 6i client/server for 4 years, but now we are forced to upgrade to 10g.
We are familiar with various Load balancing options available. The question is which option is the most "workable" in our case.

2 ISP load balancing and redundancy

Hello!!
Our small company has about 40 branches spreaded within city. Branches are connected by optic wire supplied by our ISP. So in ISP our branches are located in one VLAN. From every branch we created VPN tunnel to our server room in central office. Central office is like a cetner point. If optic wire fails to central office, there would no VPN tunnels and no network to all branches. Moreover, all the traffice goes through central office.
Now we decided to pave one more optic line to our central office. And that will increase bandwidth and redundancy.
Private network topology: There are no default gateways and ip-addresses. For examle, at first branch I will plug computer directly into media converter and at the second branch plug another computer to the media converter. After that this two computers became in one network. And can assign any ip addresses to them.
What I have: our firewall do enough work, don't want to overload it. But we have some free ports in our new cisco 3750. The question is how to do load balancing and redundanccy? Can it do load balancing according to traffic? And how load balance incoming traffic? For example, connection was established from branche's router, how this router will choose through which line make connection? By the way, at all branches we use noisy cisco
3700 series routers.

Sorry for upping 1 year old threat.
We talked to our Network Provider. They said "these two cables are coming from two different places, so there is no way to use etherchannel. You must use active-standby solution."
Relying on STP we just put two cables into 3750 stack. But with default STP settings, connection was very unstable, many packet losses and disconnections. So we found easy solution with "flex links", making one interface backup of the other. And only now I recognized that this is not a failover solution. Because, if network beyond media converter will down, link from media converter to switch would still up.
What could I do to make our L2 WAN redundant? Are there any additional STP settings.

Load balancing and Failover

Hello,
We are wondering how load-balancing and failover of tpcall() work with
WTC:
The scenario:
We have one WLS Domain and two Tuxedo Domains. The Tuxedo Domains offer
the same set of services.
In the bdmconfig.xml, we specify connection_policy as 'ON_STARTUP' for
both Remote Tuxedo Domains. We also Import (T_DM_IMPORT) the same
Tuxedo Service from both Tuxedo Domains.
Questions:
1. Is there any load-balancing of the tpcall between the two Domains? If
so, is it round-robin? If round-robin, what determines the order?
2. If it is ONLY Failover, what determines the order of the tpcall? And,
is the Failover automatic? Or do we need to code for retry on failure?
3. ON_DEMAND vs ON_STARTUP: Does ON_DEMAND drop the connection to the
remote domain upon tpterm? And does ON_STARTUP use a pool of
TuxedoConnection objects?
4. Are there any configuration parameters for
'max_number-of_connections? What determines how many simultaneous
connections can be made?
Thanks,
Suresh Mohan.

Hi Suresh,
The following are my answers to your questions.
Suresh Mohan wrote:
Hello,
We are wondering how load-balancing and failover of tpcall() work with
WTC:
The scenario:
We have one WLS Domain and two Tuxedo Domains. The Tuxedo Domains offer
the same set of services.
In the bdmconfig.xml, we specify connection_policy as 'ON_STARTUP' for
both Remote Tuxedo Domains. We also Import (T_DM_IMPORT) the same
Tuxedo Service from both Tuxedo Domains.
Questions:
1. Is there any load-balancing of the tpcall between the two Domains? If
so, is it round-robin? If round-robin, what determines the order?Yes there is a load balancing between two remote Tuxedo TDomain Gateways.
The algorithm is random, not RR. Over time this should give equal
opportunities to both remote TDomain.
>
2. If it is ONLY Failover, what determines the order of the tpcall? And,
is the Failover automatic? Or do we need to code for retry on failure?The load balancing is always there. The failover is automatic. When a
connection to a remote TDomain encountered a problem (ie network) the remote
domain will be put on retry open connection (in ON_STARTUP) and the load
balancing will not select it until the connection re-established.
However, the tpcall() that encountered the error will not be retried to send
to different destination. It is up to the application to decide whether it
want to resend. Any requests called after the error will not select the
failed Remote TDomain.
>
3. ON_DEMAND vs ON_STARTUP: Does ON_DEMAND drop the connection to the
remote domain upon tpterm? And does ON_STARTUP use a pool of
TuxedoConnection objects?TPTERM() only terminate your application session to WTC. WTC still maintain
a secured T-session to remote Tuxedo TDomain. WTC does not use a pool of
TuxedoConnection Objects, the object stored in the JNDI refers to WTC.
>
4. Are there any configuration parameters for
'max_number-of_connections? What determines how many simultaneous
connections can be made?No. As described in #3, there is no need to use connection pool in WTC. WTC
uses session and virtual circuit design concept as Tuxedo TDOMAIN, the
logical pool is created/destroyed dynamically. That is the reason why you
can have a lot of TPACALL() outstanding at the same time. (The limitation is
the availability system resource.)
>
>
Thanks,
Suresh Mohan.Regards,
Hong-Hsi :-)

Discussion on load-balance and load-sharing

Hi, I found a article, which discuss the difference between load-balance and load-sharing. I think the explanation is pretty good, please see below. But I still have a question: how can we decide to choose one the both balance in the production environment ? Thank you
"In short, load balancing tries to distribute traffic evenly over multiple paths, whereas, load sharing intends to do it (for the lack of a better term) equally. True load balancing is difficult to achieve. For example, let's say there were two links (100 mbps and 300 mpbs) and a router needed to send out 600 mbps of traffic. Load balancing would distribute the traffic evenly, sending 300 mbps on each link. On the contrary, load sharing would divide the traffic equally based on the available resources, sending 200 mbps on the slower link and 400 mbps on the faster one. "

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That's not how Cisco uses the terms, and generically they are often used almost interchangeably.
Cisco uses load balancing as the catch all for how a single L3 device routes across multiple paths to the same destination. Equal metrics or equal actual load distribution are not required. Most often, load balancing will be discussed with ECMP, but unequal path loading balancing will include Cisco's proprietary IGPs, such as EIGRP.
Cisco uses load sharing when using multiple paths when a single L3 devices doesn't normally route across multiple paths or multiple L3 devices are involved. Cisco load sharing discussions usually revolve around BGP.
Generically, I would say load balancing has more of a dynamic aspect to it, i.e. something is trying to actively balance traffic across multiple paths, while load sharing might mean multiple paths are utilized but not actively dynamically balanced.
I'm unsure what's your question with a production environment.

Load balancing and RFC problem

Hi!
I have a problem regarding load balancing and RFC's. We use the follow function in librfc32.dll (from VB6) for RFC calls: RfcOpenExt It's working fine no problem, but from now on we will have to use the this funcion due to load balancing: RfcOpenExtV3
The only difference between the two functions is the parameters. RfcOpenExtV3 has 5 additional parameters:
intLoadBalance1, strLbHost1, strLbSysName1, strLbGroup1, intSapGui1
I asked our tech guys for the details so that I can set up the parameters (double check everything) and the RfcOpenExtV3 doesn't working. Return value is zero.
Have somebody faced with this issue before?
Thanks in advance!

Hi,
1. Probably this link may help.
[http://help.sap.com/saphelp_nw04/helpdata/en/22/042f18488911d189490000e829fbbd/content.htm]
Especially see the function parameters on this page,
which are the bottom.
regards,
amit m.

Load Balancing and Asynchronous Multimaster Replication

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