Prof. Eitan Bachmat

Online, remote, data replication is critical for today's enterprise IT organization. Availability of data is key to the success of the organization. A few hours of downtime can cost from thousands to millions of dollars With increasing frequency, companies are instituting disaster recovery plans to ensure appropriate data availability in the event of a catastrophic failure or disaster that destroys a site (e.g. flood, fire, or earthquake). Synchronous and asynchronous replication technologies have been available for a long period of time. Synchronous replication has the advantage of no data loss, but due to latency, synchronous replication is limited by distance and bandwidth. Asynchronous replication on the other hand has no distance limitation, but leads to some data loss which is proportional to the data lag. We present a novel method, implemented within EMC Recover-Point, which allows the system to dynamically move between these replication options without any disruption to the I/O path. As latency grows, the system will move from synchronous replication to semi-synchronous replication and then to snapshot shipping. It returns to synchronous replication as more bandwidth is available and latency allows.