Continuous data availability through replication

With continuous data availability, instance 2 is immediately available, with all its cache data, on a different module after a module has failed.

The continuous service availability features of Gear6 Web Cache automatically and transparently fails over to a new module when a module failure occurs, and normal operations resume as the new module is loaded with cache data.

But for some applications, cache performance may be unacceptably reduced as the rebuilding takes place. For this reason Gear6 Web Cache can also be deployed with replication, providing continuous data availability. With replication, cache data is always duplicated in another location, and when a module fails, the Memcached instance on the failed module is immediately replaced with another one already containing the same data. Memcached operations continue without interruption or slowdown. Spikes in database and application load are avoided.

Replication typically requires twice as much memory but is often justified for large and mission-critical applications. And because of the Gear6 Web Cache hybrid DRAM-flash architecture, a replicated Gear6 solution is typically still much less costly to purchase and operate than alternative Memcached solutions.