Improve Business Continuity

CA XOSoft's WANSync is a software that does asynchronous replication for applications like Oracle, MS Exchange, SQL, IIS, and others across your WAN or LAN to improve their uptime

Wednesday, September 05, 2007

Minimum downtime and data protection for all production servers are key challenges most CIOs are toiling with today. That's why, most organizations today have implemented Disaster recovery sites to meet these challenges. In any DR deployment, timely replication of data plays a major role. For this, what's required is a solution that will replicate data asynchronously and in real time. In this article, we'll talk about one such software called WANSync from CA. The software provides full DR capabilities for applications like Oracle, MS Exchange, MS SQL, IIS, and even your file server. In addition, it also supports applications on multiple platforms like AIX, Solaris, and Red Hat, which are either 32 or 64 bit. It basically comprises of a manager and an agent engine. The manager application lets you manage the replication activity on the main server, and the agent needs to be deployed on its replica at the DR site.

Creating replication scenarios with WANSync is simple because it uses very user-friendly wizards. In this article we'll show how you can perform asynchronous data replications between two sites located at different geographical locations using WANSync. Our setup included a Windows 2003 Server Domain Controller and two additional Windows 2003 Servers running on MS SQL and Exchange Servers. Both servers were connected to the Domain Controller called 'master site.' We then created a DR site on a different network subnet. We ran both MS SQL and Exchange Servers on this site and configured them to connect to the Domain Controller on the master site. Here the idea was to create a replica of the applications present on master site.

Remote Installation wizard let's you deploy WANSync agents to the remote applications, which will be used for replication

Deploying WANSync
The software must be installed on your Domain Controller. You'll need the .NET framework on the server as a prerequisite for installing WANSync. There are three key applications in WANSync. First is the Manager, which we already talked about. Second is the Remote Install, which as the name suggests helps you install agents to remote servers. Third is the CLI, which provides administrators with a command line interface serving as an alternative to the WANSync Manager.

The first step is to install agents on all servers at your DR site, so that the master site data can be replicated easily across your WAN link. To do this, launch XOSoft Remote Installer from Start>Programs of your Domain Controller. This will start a wizard, which searches for all systems that are connected to your Domain Controller from the master as well as the remote site. Once you get a list of all the machines, select the ones where you want to install the agent. These will be the servers on your remote site, which would then become replicas of the servers running in your master site. These will be located in your left panel, and after selecting them, they'll move to the right panel of the software's window.

Please note that you do see both master and replica servers for all your applications here. So you should see two servers running on SQL Server, another two on Exchange, and so on, depending upon the servers you're replicating. Click 'Next' and the wizard will deploy the agent engine on the servers that will become the replicas. At the end of this, you'll be shown a deployment summary report.

Initiating the Replication process
For this, run the WANSync Manager from Start>programs >CA WANSync on your Domain Controller. The WANSync Manager will ask you to define a scenario. Select 'new Scenario,' and you'll be shown several of them to choose from. Some of these include file server, Exchange Server, IIS, MS SQL, etc. We used MS SQL server. After selecting the scenario, you will be asked to fill-in the IP address or host name of your master and replica servers, so that the manager can configure the replication parameters between the two hosts. Then the wizard searches for both hosts and also shows you the MS SQL database parameters that will be set automatically. You can even change the parameters according to your organization's needs. Now click Next to save the parameters and finally Finish. This will complete the entire scenario configuration on WANSync. On the screen you will see a diagrammatic representation of both master and replica and also the amount of data that has been synced between two hosts.

The WANSync Manager shows you the entire process of replication and synchronization between the master and replica servers. It also lets you define multiple DR scenarios

Recovering Data
Now let's come to the fun part. Suppose your master MS SQL Server fails or crashes due to whatever reason. You want to ensure that downtime is minimized. All you have to do is configure the replica SQL Server as the Master server. To do this, simply change the name of your replica SQL Server instance to the Master SQL Server. This can be done from the SQL Enterprise Manager console of your SQL Server. All clients will then start connecting to the replica server. The performance here will, of course, depend upon the bandwidth available on your WAN link.

One point to keep in mind is that the software doesn't support automatic failover to the replica server. It will send an alert by email if a master application goes down, but the switchover to the replica server has to be done manually.

For automatic failover, you need to deploy another version called WANSync with HA. This also does load balancing between the master and replica servers for better performance.

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