FW 05.01.00 and SW 07.01.00 HP StorageWorks SAN High Availability Planning Guide (AA-RS2DC-TE, June 2003)

Introduction to HP Fibre Channel Products
25SAN High Availability Planning Guide
Edge Switches
Like directors, edge switches also provide high-performance, dynamic
connections between end devices in a Fibre Channel switched network. Edge
switches also support mainframe and OSI computing environments.
Through non-blocking architecture and limited FRU redundancy, edge switches
also offer high availability and high-performance bandwidth. Although edge
switches do not offer the redundancy, availability, or port count of an
enterprise-class director, they offer a much lower cost connectivity option. Edge
switches should be installed for:
■ Implementation as the principal building block of a small-scale SAN or as a
consolidation point for enterprise-class SANs.
■ Departmental and workgroup connectivity.
■ Applications where distributed storage predominates.
Edge switches also provide connectivity between servers and devices
manufactured by multiple OEMs. To determine if an OEM product can
communicate through edge switch connections, or if communication restrictions
apply, refer to the product publications or contact your HP marketing
representative.
Edge Switch Performance
Edge switches provide an availability of 99.9% through a redundant configuration
of power supplies and cooling fans. When an active FRU (power supply or fan)
fails, the backup takes over operation automatically to maintain switch and Fibre
Channel link operation. Availability is also provided through concurrent firmware
upgrades and spare or unused Fibre Channel ports.
Along with an availability factor of 99.999%, edge switches offer the same
general performance features as directors, including high bandwidth, low latency,
local control, low communication overhead, multiple topology support, and
multiple service class support.