Dell PowerVault 221S Optimizing Dell SCSI Solutions - Page 22

A REFERENCE GUIDE FOR OPTIMIZING DELL™ SCSI SOLUTIONS VER A02 a failover condition, access rights to the disk array assigned to the failed node is transferred to the other node. An active/active cluster node must be sized appropriately to handle the load of both nodes (in the event of a failover). The term active/passive refers to failover cluster configurations in which one or more cluster nodes is actively processing requests for cluster applications while at least one cluster node simply waits for an active node to fail. An active/passive configuration is more costly in terms of price/performance because one or more servers sits idle most of the time. It is appropriate for business-critical systems since the application can use the full power of another server in case of a failure. Dell PowerEdge Clustered systems fully support both cluster topologies with MSCS. Figure 4-4 Cluster Topology Cabling Example PV22xS - Common Features and Capabilities Regardless of what topology is ultimately selected, the PV22xS provides a basic set of common features and capabilities. SCSI ID Assignment SCSI standard requires that all devices on the SCSI bus have a unique address, called a SCSI ID, with a maximum of 16 devices that can reside on the bus. The SCSI ID for the enclosure devices are hardwired by the enclosure backplane. PV22xS supports 15 of these devices with the SCSI controller in the host system using the remaining SCSI ID. In Cluster topology, however, the enclosure will give up one of its HDD SCSI ID, which will PAGE 22 11/17/2005