FC interface to SAS

An FC-to-SAS bridge enables communication between Fibre Channel networks and SAS storage devices by converting data packets between the two protocols.

Overview

Fibre Channel (FC) and Serial Attached SCSI (SAS) are distinct storage technologies.

F

C is primarily used in SANs (Storage Area Networks) to transport SCSI commands over a high-speed network, offering high performance and scalability, while SAS is a point-to-point interface used to connect disk drives directly to servers or storage arrays, providing high reliability and low latency. Because these protocols are not natively compatible, a bridge device is required to interface between them. FC-to-SAS Bridge FunctionalityAn FC-to-SAS bridge, such as the Tamar FCSAS bridge, acts as a two-way interface.

It receives data packets from the Fibre Channel network, converts them into SAS commands, and forwards them to SAS-enabled storage devices like disks or tape drives. The bridge also handles the reverse process, allowing SAS devices to communicate back to the FC network.

Each SA

S device can support multiple logical units (LUNs), which the bridge maps to the FC network for access by servers.

Configuration and Management

Bridges are typically managed via a CLI or Ethernet management interface. Key configuration steps include: Connecting FC and SAS cables to the appropriate ports on the bridge. Assigning a unique bridge name within the SAN or MetroCluster configuration.

Configuring F

C port speeds according to the supported data rates (e.g., 8, 16, or 32 Gbps depending on the bridge model). Optionally using in-band management through FC ports for firmware updates and monitoring. Proper cabling and adherence to speed ratings are critical to ensure full performance and avoid data loss.

Some bridges also support multipath configurations to enhance redundancy and availability.

Performance Considerations

Latency: SAS provides low-latency, high-speed access to storage devices, while FC adds network transport overhead but allows centralized storage access. Scalability: FC networks can connect multiple servers to a shared storage pool, whereas SAS is typically used for direct-attached or small-scale shared storage. Compatibility: The bridge ensures that servers on an FC SAN can access SAS storage without requiring native SAS support on the host.

Use Cases

Integrating legacy SAS storage into an existing FC SAN. Expanding storage capacity in environments where FC is the primary network. Enabling centralized management of SAS devices across multiple servers.

In summary, an FC-to-SAS bridge is essential for connecting Fibre Channel networks to SAS storage, providing protocol conversion, centralized management, and enabling high-performance access to SAS devices from SAN-connected servers.