Q-Logic 8100 SERIES manual Boot-from-SAN Configuration Topologies, Single-Path Topology

8–Configuring FCoE in a Linux Environment Boot-from-SAN

Storage Array Requirements

Some storage arrays cannot support boot-from-SAN for specific environments. Consult the storage array documentation to confirm that the array and the firmware support boot-from-SAN. Consider the storage array and any limitations regarding boot-from-SAN.

Create and present an appropriately-sized LUN to the QLogic 8100 Series Adapter port. Ensure that:

The adapter port has exclusive access to this LUN.

The LUN host type matches the operating system that is to be installed on this LUN.

Each server has its own dedicated boot LUN. Two servers cannot share the same boot LUN.

Boot-from-SAN Configuration Topologies

One of the benefits of SAN adoption, and in turn, Boot-from-SAN, is high availability, which is not easily achieved in a local boot scenario. Before proceeding to the detailed instructions about configuring boot-from-SAN, determine the level of fault tolerance and high availability required for boot-from-SAN installations. The following sections describe two boot-from-SAN topologies: single-path configuration (least fault tolerant) and multipath configuration (most fault tolerant).

Single-Path Topology

Asingle-path topology is the simplest configuration for boot-from-SAN for QLogic 8100 Series Adapters. The single-path configuration consists of a single adapter port connected to a converged networking switch (FCoE switch), which is then connected to the storage controller (SP) of a storage array. A single-path configuration does not use redundant components, and therefore, is not recommended for mission-critical servers.

However, single-path topology does offer some degree of fault tolerance, because the QLogic 8100 Series Adapter can configure alternate boot LUNs. As shown in Figure 8-12, if the primary boot device (LUN1) fails, or if it is not available at boot time, the QLogic adapter automatically tries to boot from the alternate boot device (LUN2). Up to four alternate boot devices can be configured, which provides failover protection by redirecting the boot device without user intervention.

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