Dell PowerVault 221S (SCSI) - Manual (Page 22)

A REFERENCE GUIDE FOR OPTIMIZING DELL™ SCSI SOLUTIONS VER A02
PAGE 22 11/17/2005
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