Compaq ProLiant 7000 Deploying the ProLiant Cluster for NetWare 4.2 - Page 7

'HSOR\LQJ WKH 3UR/LDQW &OXVWHU IRU 1HW:DUH   Failover and Recovery States Figure 2 illustrates the failover and recovery process. If no communication between the servers can be established across any of the three lines of communication, the server that has lost connections to the network and storage will enter failover state. At the same time, the other node, in this case, Server B, will enter the recovery state (Figure 2A). Upon entering the recovery state, Server B assumes responsibility for Server A volumes and clients (Figure 2B). Security and licensing are maintained by transferring NDS rights to the surviving server. Total failover time corresponds to the time necessary to detect the failure and complete the failover process. During a failover, the remaining server must mount the new volumes, launch any active server-based applications that were running on the failed device, and transfer security and license information. NHAS also allows manual failover of shared volumes at any time by pressing F at the NHAS console. By forcing a failover, you can remove a server from the network for scheduled maintenance without interrupting access to that server's volumes. Accessed by Node B only Accessed by Node B only Volume 1 Volume 2 Compaq RAID Array 4000 Disabled Server Fibre Channel Storage Hub Fibre Channel Arbitrated Loop Dedicated Interserver Direct Link Server Node B Local Area Network NetWare Interconnects Volume A Volume B Server A Server B Logical Connections Network Clients Data Inter-server Monitoring Data and Monitoring A. Node B Entering Recovery State Figure 2. Failover and Recovery B. Node B Assuming Responsibility for Node A's Volumes 0096-0699-A