Network and disk drivers

Network drivers

Each node in the cluster runs an instance of the Cluster Network Driver, Clusnet.sys. The Cluster Network Driver is responsible for:

• Providing highly available intracluster communication by monitoring and leveraging all network paths between nodes.
• Routing messages for intracluster traffic.
• Detecting communication failure. Each node's Cluster Network Driver exchanges periodic messages, called heartbeats, with the Cluster Network Driver on the other active nodes. If a node fails to respond to a heartbeat message, the Cluster Network Driver on the node that detects the failure notifies the Cluster service that the corresponding network interface has failed. If all other intracluster network interfaces for that node fail, the Cluster service will then initiate failover of the node. Note that failure of a node to respond to a heartbeat message can be caused by node failure, network interface failure, or network failure.

The Cluster Network Driver on each node uses the Internet Assigned Numbers Authority (IANA)-assigned port of 3343. For information on removing malicious processes bound to the cluster network ports, see General administrative problems.

Disk drivers

Each node in the cluster runs an instance of the Cluster Disk Driver, Clusdisk.sys. The Cluster Disk Driver is responsible for:

• Maintaining exclusive ownership of cluster disks. Only the node that owns the physical disk resource can access the disk. All other nodes cannot access this disk.
• Placing reservations on disks so that they cannot be accessed by another node. If a node owns a particular disk and that disk is online, then reservations placed by Clusdisk will prevent other nodes from accessing that disk. For disks that are offline, Clusdisk will prevent disk access by blocking I/O on the local system.