Monday, October 29, 2012

Tungsten Replicator 2.0.6 released - Multi-Master replication made easy and more

Tungsten Replicator version 2.0.6 was released today.

You can get both the binaries and the source code at the project's downloads page.

This release contains many bug fixes, and various improvements. All of them are listed in the Release Notes. The most interesting ones are the improvement in multi-master topologies. Using this release with star topologies you will get less traffic than before, because we have reduced some duplication of transaction history logs that were sent between servers.

And speaking of multi-master topologies, this release includes the cookbook recipes mentioned in this blog some time ago. Normally, these recipes are in their own repository, but for the 2.0.6 binaries we've made an exception and included them in the distribution. You can finally deploy a star or fan-in topology with ease.

Other improvements are a batch loader for data warehousing and more stability for heterogeneous replication. There are also more instrumentation that helps when you are using row-based replication. trepctl status -name tasks gives more detail than before, to let you know what's happening when dealing with huge transactions that were transferred in several chunks.

For an example of deploying a star topology, let's see a quick demo:

  1. First, we get the binaries:
    $ mkdir someplace
    $ cd someplace
    $ wget
  2. Then, we make sure that we have fulfilled the pre-requisites
  3. Inside the cookbook directory you will find a script named simple_services. You should copy it in a directory that is in your $PATH (for example, $HOME/bin)
  4. We can now set the cookbook recipes for our purpose. Inside the ./cookbook directory, there is a file named (There is such a file for every topology). The file looks like this:
    export ALL_NODES=($NODE1 $NODE2 $NODE3 $NODE4)
    # indicate which servers will be masters, and which ones will have a slave service
    # in case of all-masters topologies, these two arrays will be the same as $ALL_NODES
    # These values are used for automated testing
    # for all-masters and star replication
    export MASTERS=($NODE1 $NODE2 $NODE3 $NODE4)
    export SLAVES=($NODE1 $NODE2 $NODE3 $NODE4)
    export HUB=$NODE3
    # MMSERVICES are the names used for services when installing multiple masters
    export MM_SERVICES=(alpha bravo charlie delta echo foxtrot golf hotel)
    export HUB_SERVICE=charlie
  5. If you have 4 nodes, all you need to do is fill in the nodes list, making sure that the server you want to use as a hub is the third one.
  6. If you have more nodes, or less nodes, you also need to adjust the lists for ALL_NODES, MASTERS, and SLAVES.
  7. Once the servers list is ready, you can start the installation.
    $ ./cookbook/
  8. If you have all your pre-requisites right, you will only see the list of servers being installed and at the end the list of services being activated for each server.
  9. To make sure that the cluster is installed correctly, you can run
    $ ./cookbook/
    $ ./cookbook/
  10. If you need it, you can also remove the cluster using
    $ ./cookbook/

Happy hacking!

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