Both scenarios (the use of a single network and the use of two physically separate networks)  are supported for Internet Small Computer System Interface (iSCSI)-based and LAN-based  access networks to SAN Volume Controller. Redundant paths to volumes can be provided in  both scenarios.  For iSCSI-based access, the use of two networks and separating iSCSI traffic within the  networks by using a dedicated virtual local area network (VLAN) for storage traffic prevent  any IP interface, switch, or target port failure from compromising the host servers’ access to  the volumes. A  clustered system  of SAN Volume Controller nodes that are connected to the same fabric  presents logical disks or  volumes  to the hosts. These volumes are created from managed  LUNs or  managed disks  (MDisks) that are presented to SAN Volume Controller by the storage  subsystems and grouped in  storage pools . The following distinct zone sets are shown in the  fabric:  The logical architecture of SAN Volume Controller is shown in Figure 9-2, which also shows  how different storage pools are built by grouping MDisks, and how the volumes are created  from those storage pools and presented to the hosts through I/O groups (pairs of SAN  Volume Controller nodes). As shown in Figure 9-2, Vol2, Vol7, and Vol8 are mirrored volumes,  or volumes with two copies, with each copy in a different storage pool. For more information  about volume mirroring, see “SAN Volume  Controller volume mirroring” on page 366. Figure 9-2 Overview of a SAN Volume Controller clustered system, hosts, and storage subsystems FlashSystem 840 Disk Subsystem B Chapter 9. Product integration  343 GLYPH<SM590000> Host zones, in which the hosts can see and address SAN Volume Controller nodes and  access volumes GLYPH<SM590000> Storage zones, in which SAN Volume Controller nodes can see and address the  MDisks/LUNs that are presented by the storage subsystems