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Achieve Faster, Cheaper and Better Recoveries Using Asynchronous Replication

Synchronous replication may be viewed by users as the “Gold’ standard when it comes to achieving the highest levels of application availability for business continuity and disaster recovery. But as I previously discussed, using synchronous replication for business continuity and disaster recovery can actually take longer and cost more for organizations to remotely recover applications than if they use asynchronous replication. Now organizations can use asynchronous replication software like InMage Systems Scout to deliver the same or better results as synchronous replication at a substantially lower cost.

To deliver synchronous type results using asynchronous replication software, Scout does the following:

  • Uses continuous data protection (CDP) to track all changes to application data. One of the knocks on asynchronous replication is that it may only replicate the delta changes over a specified period of time. When configured this way, the software does not track every write nor does it constantly send changes to the target but only replicates changed blocks at intervals (say every 15 minutes) as defined by the user. Scout uses CDP so it functions just like synchronous replication in that maintains write-order fidelity by capturing and replicating all changes to application data. This ensures organizations can roll forward or roll back to recover to any point-in-time, not just a specified a periodic point in time.
  • Is application aware. To recover an application at a remote site requires application integration so that data at the target site is kept in a consistent and recoverable state. Scout integrates with applications such as Microsoft Exchange, SharePoint and Oracle so that organizations can fail over and recover those applications at a remote location.

However Scout “one-ups” synchronous replication in three important ways:

  • Organizations can keep their existing data center infrastructure in place. Synchronous replication if done on a storage system can require organizations to first purchase like storage systems for the source and target site, migrate all of their production application data to the new storage system and then license the synchronous replication software. This can run into the millions of dollars to configure. Using Scout, organizations can keep their existing infrastructure (servers and storage) in place and replicate between dissimilar systems at the source and target sites. Not only does this eliminate the up-front costs but it speeds the deployment of the solution.
  • Offers checkpoints for point-in-time recoveries. The downside of using synchronous replication that no one likes to talk about is that it replicates both good and bad data. So if a corruption occurs or bad data is loaded into a database at the production site, it is automatically replicated to the target so organizations still may need to resort to recovering the application data from a backup. Using Scout and its CDP technology, even if data corruption occurs or bad data is loaded, organizations can roll back to a known good point-in-time and recover their data without needing to resort to some other recovery mechanism (snapshots or backups).
  • Can recover the application faster. This almost seems like a paradox that one can recover an application faster using asynchronous replication than synchronous but it may hold true in most environments. The only way a recovery will occur faster using synchronous replication is if all components including the server, network and storage are in sync. If only data on the storage system is being synchronously replicated, organizations still need to bring up servers at the remote site, move the IP addresses to the new servers and then hope you have a consistent point in the replicated data from which to recover. Since you have to do all of this anyway, Scout enables organizations to accomplish all of this without all of the associated server, network and storage expenses.

Synchronous replication is a great technology and is certainly needed to satisfy some application requirements. But organizations need to take a hard look at the benefits they expect to receive when deploying synchronous replication and the benefits that they actually will receive. Products like InMage Systems Scout have significantly closed the gap between what synchronous and asynchronous replication software delivers. The features that Scout delivers are now so substantial that most organizations will realize all of the benefits (and more!) of synchronous replication by using Scout while simultaneously lowering their costs and improving their time to recovery for more of their corporate applications.


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