RAPID FAILURE DETECTION AND TRANSPARENT RECOVERY
ExpressCluster X WAN recovers all data committed to the primary system disk without loss should a primary application, system, or site outage occur. Using either a periodic network request or heartbeat signal, it can automatically execute recovery procedures if a system fails to receive required heartbeat signals from another system. It can detect application and resource (e.g. disk) failures and trigger appropriate recovery action including failover to a standby system. In the failover process, the standby system takes over the virtual host identity from the primary system so large number of client systems can easily reestablish access to target server applications without manual reconfiguration.

FLEXIBLE DATA MIRRORING FOR ALL CRITICAL DATA PROTECTION NEEDS
ExpressCluster X WAN provides an application transparent data mirroring function that allows users to easily choose between synchronous and asynchronous data mirroring modes to meet a wide range of data protection needs.

Synchronous data mirroring technology enables full data protection by ensuring data written to the mirrored disk on the primary system is also written to the mirrored disk on the standby system in real time as a single transaction. Using synchronous mirroring technology, it ensures that no data committed to the mirrored disk on the primary system is dropped and no data is lost—if a failure occurs, users can readily access an up-to-date exact copy of all data on the standby system.

ExpressCluster X WAN also supports asynchronous data mirroring for best-effort data protection by allowing trade-off of potential data loss for lower cost network infrastructure. Asynchronous data mirroring differs from synchronous data mirroring by allowing data write operations to complete to the mirrored disk on the primary system without verifying data write completion on the standby system. Instead, data write operations to the standby system will be performed on a best-effort basis depending on system and network conditions with the risk that some data will be lost if the primary system fails before the write operations to the standby system can be performed.

Depending on specific user data protection needs, it supports a combination of different mirrored disks using synchronous and asynchronous data mirroring in the same cluster. Unlike other solutions, ExpressCluster X WAN allows users to easily change between synchronous and asynchronous mirroring.

ADVANCED OPTIONS FOR INTEGRATED LOCAL AND REMOTE RECOVERY
ExpressCluster X WAN provides advanced options for hybrid disk cluster configuration support. With the hybrid disk option, ExpressCluster X WAN provides both local and remote recovery capabilities. For localized system failures such as hardware or software failure on the primary server, ExpressCluster X WAN will perform automated recovery to a local standby server at the same site with access to the same shared storage system as the primary server. For site wide failures due to events such as network disruption or earthquakes, it will perform automated recovery to a remote standby server at the remote standby site with access to mirrored data storage. The key benefit for such configuration is to enable the fastest possible system recovery for the different types of failures using a single integrated solution.

EASY WORKLOAD MIGRATION MITIGATES PLANNED DOWNTIME
Unlike unplanned downtime, planned downtime is scheduled to perform necessary maintenance at times that minimize business impact such as planned maintenance to apply security patches for OS or applications. In such situations, ExpressCluster X WAN can easily move multiple applications and data workloads between servers with minimal system disruption and still allow planned maintenance on all servers to be performed with little or no restrictions. ExpressCluster X WAN can effectively eliminate the need to schedule extended planned downtime during off-business hours for maintenance purposes and reduce planned system downtime from hours to minutes.