Figure 3. SC4020 Storage System with Two SC280 Expansion EnclosuresStorage Center CommunicationA Storage Center uses multiple types of communication for both data transfer and administrativefunctions.Storage Center communication is classified into three types: front end, back end, and systemadministration.Front-End ConnectivityFront-end connectivity provides I/O paths from servers to a storage system and replication paths fromone Storage Center to another Storage Center. The SC4020 storage system provides the following typesof front-end connectivity:• Fibre Channel: Hosts, servers, or Network Attached Storage (NAS) appliances access storage byconnecting to the storage system Fibre Channel ports through one or more Fibre Channel switches.Connecting host servers directly to the storage system, without using Fibre Channel switches, is notsupported.When replication is licensed, the SC4020 can use the front-end Fibre Channel ports to replicate datato another Storage Center.• iSCSI: Hosts, servers, or Network Attached Storage (NAS) appliances access storage by connecting tothe storage system iSCSI ports through one or more Ethernet switches. Connecting host serversdirectly to the storage system, without using Ethernet switches, is not supported.12 About the SC4020 Storage System
