OnCommand Site Recovery Plug-in for Microsoft enables you to quickly recover from various storage system and site-wide failures by taking different actions depending on the type of failure the MetroCluster cluster resource detects.
In general, the site recovery plug-in works for a MetroCluster storage environment by taking the following actions:
- The plug-in verifies that the storage used by the application that you have added a MetroCluster cluster resource to is online.
- The plug-in allows the application to start.
- When the plug-in detects a storage disruption, it initiates a recovery scenario.
Recovery from storage system failures
Storage system failures involve a complete loss of the storage controller and disk shelves, resulting in the following recovery scenario:
- The site recovery plug-in detects the storage failure.
- The WSFC brings the application offline and restarts the plug-in.
- The plug-in verifies the disaster conditions.
- The plug-in initiates "cluster failover on disaster" to restore system availability at the disaster site.
- The plug-in monitors the storage system for takeover completion.
- The WSFC restarts the application.
Recovery from site-wide failures
With site-wide failures, there is a complete loss of storage system and Windows cluster nodes, resulting in the following recovery scenario:
- The WSFC moves application and site recovery plug-in instances to the surviving cluster node at the surviving site.
- The WSFC restarts the plug-in.
- The plug-in verifies the disaster conditions.
- The plug-in initiates cluster failover to restore availability at the disaster site.
- The plug-in monitors the storage system to be sure takeover has completed.
- The WSFC restarts the application, which is now using storage at the surviving site.
Recovery from other failures
Other failures include the following:
- Controller and shelf failures, which are managed by MetroCluster
- Windows cluster node failures, which are managed by the WSFC
- Network failures, which are handled by the WSFC as long as a quorum can be established (which depends on the quorum settings)
