4.3.3 Architecture The IBM TotalStorage SAN Volume Controller is a modular solution that consists of a Master Console for management, up to eight cluster nodes (added in pairs), and dual UPS for write cache data protection (Figure 4-7). The nodes are the hardware elements of the SAN Volume Controller. SVC combines these nodes (servers) to create a high availability cluster. Each of the servers in the cluster is populated with 4 GB of high-speed memory, which serves as the cluster cache. Figure 4-7 SVC components The storage engines (or storage nodes) are always installed in pairs and combined into a high availability cluster. SVC nodes within the cluster are grouped into pairs (called I/O groups), with a single pair