> # Fabric Optimization with VSANs

> Generally, separate physical fabrics have a high level of switch management and have a higher implementation cost. The ports in each island also may be over-provisioned depending on the fabric configuration.

> By using the Cisco MDS-specific VSAN technology, you can have greater efficiency between these physical fabrics by lowering the cost of over-provisioning and reducing the number of switches to be managed. VSANs also help you to move unused ports nondisruptively and provide a common redundant physical infrastructure.

> VSANs enable global SAN consolidation by allowing you to convert existing SAN islands into virtual SAN islands on a single physical network. It provides hardware-enforced security and separation between applications or departments to allow coexistence on a single network. It also allows virtual rewiring to consolidate your storage infrastructure. You can move assets between departments or applications without the expense and disruption of physical relocation of equipment.

> Note You can configure VSANs in any Cisco MDS switch, but you only can enable FICON in up to eight of these VSANs. The number of VSANs configured depends on the platform.

> Mainframe users can think of VSANs as being like FICON LPARs in the MDS SAN fabric. You can partition switch resources into FICON LPARs (VSANs) that are isolated from each other, in much the same way that you can partition resources on a zSeries or DS8000. Each VSAN has its own set of fabric services (such as fabric server and name server), FICON CUP, domain ID, Fabric Shortest Path First (FSPF) routing, operating mode, IP address, and security profile.
> FICON LPARs can span line cards and are dynamic in size. For example, one FICON LPAR with 10 ports can span 10 different line cards. FICON LPARs can also include ports on more than one switch in a cascaded configuration. The consistent fairness of the Cisco MDS 9000 switching architecture means that “all ports are created equal,” simplifying provisioning by eliminating the “local switching” issues seen on other vendors’ platforms.
> Addition of ports to a FICON LPAR is a nondisruptive process. The maximum number of ports for a FICON LPAR is 255 due to FICON addressing limitations.

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