Storage Area Networks: Designing and Implementing a Mass Storage System

8.7 Fibre Channel Switches

8.7.1 Brocade Silkworm 2800 Switch

Hewlett-Packard resells the Brocade SilkWorm 2800 Fibre Channel Fabric Switch. This is a high-performance 16-port fabric switch. Its high-availability features include redundant fans and optional redundant hot-swappable power supplies . The Gigabit Interface Converters are hot-swappable, as well.

The switch s ports automatically determine the port type: point-to-point, loop, or Inter-Switch Link (ISL). Switches can be cascaded, and the architecture allows for up to 239 switches in the fabric. The certified maximum is 32 switches over seven hops.

Supported GBIC types are shortwave, longwave , and passive copper .

The switch can be managed by SAN Manager DM, SNMP, Telnet, or Brocade s optional Brocade Web Tools. You can connect to it for management by means of an RJ-45 Ethernet connection or inline, over a Fibre Channel link.

8.7.2 HP Switch F16

The Hewlett-Packard SureStore E Switch F16 is a 16-port fabric switch. Its high-availability features include redundant power supplies and fans. The fan cage is hot-swappable.

The switch allows Fibre Channel connections to either private or public arbitrated loops or to a Fibre Channel fabric. The EPL (Enhanced Private Loop) feature is supported on HP-UX 11.0 and HP-UX 10.20 with the appropriate patches. This mode is used to allow a legacy private loop device to be attached to a fabric but operate as if it were still in a Private Loop Direct Attach (PLDA) environment. This provides connection transparency between legacy devices and the fabric.

The switch can be used to connect 16 Fibre Channel devices together. Devices may be either a direct attachment to the switch (as in a host system, or a Fibre Channel peripheral); or may be through an FC-AL Hub (provides a local loop at that particular attachment); or by way of a bridge for connecting SCSI tape or disk configurations.

The switch is fully compatible with HP s Hub L10, Hub S10, and Bridge FC 4/2. The switch supports legacy systems, such as K-Class, D-Class, T-Class, and V-Class, running the above-mentioned HP-UX 10.20 or 11.0 operating system versions. The host systems use the A3404A, A3636A, A3591B, A3740A, and A5158A Fibre Channel host bus adapters.

The switch is delivered with one G_Port card for cascading with other switches. The unit ships with no GBICs (GigaBit Interface Converters) installed. From one to four GBIC options may be used, but at least one must be ordered. Each GBIC option provides four GBICs, which are installed into any desired empty position in the switch. It is possible to use either shortwave or longwave GBIC optics. No more than one longwave option may be used at this time.

Only one loop connection may be used per Hub. There is a limit of one loop master per Fabric Port. If more than one loop master (FL_Port) is used, one will remain inactive until such time as the first FL_Port fails.

The switch operates as a full-bandwidth crosspoint connection device, capable of providing up to eight concurrent connections. Each connection operates at full 1 Gbps speed. This is a significant improvement over a loop configuration, which has a total speed of 1 Gbps, but is a shared polling environment.

The Gigabit Fibre Channel Switch supports no more than two uncascaded switches per cluster/configuration. There may be no more than eight hosts per pair of switch connections. This allows for a High Availability (HA) redundant path configuration to maximize the availability of the host systems and mass storage. See Figure 8-30.

The switch can be managed through SAN Manager (DM), Fibre Channel Manager, and Storage Node Manager.