McDATA Sphereon 4300 Specifications download pdf (Page 121)

Planning Considerations for Fibre Channel Topologies

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Planning Considerations for Fibre Channel Topologies

• 11 to 1 fan-out region - Eleven NT servers with I/O capabilities of

10 MBps and 1,000 IOPS are fabric-attached through a 32-port

edge switch. The primary applications are e-mail and online

transaction processing (OLTP). Because bandwidth use is light

and noncritical, the servers are connected to the core director with

a single ISL that is intentionally oversubscribed (1.1 Gbps plus

Class F traffic). The servers are connected to storage devices with

I/O capabilities of 11,000 IOPS.

• 6 to 1 fan-out region - Six servers with I/O capabilities of 20

MBps and 1,500 IOPS are fabric-attached through a 16-port edge

switch. Bandwidth use is light to medium but critical, so the

servers are connected to the core director with two ISLs (0.6 Gbps

each plus Class F traffic). The servers are connected to storage

devices with I/O capabilities of 9,000 IOPS.

• 3 to 1 fan-out region - Three servers with I/O capabilities of 30

MBps and 2,000 IOPS are fabric-attached through a 16-port edge

switch. Bandwidth use is medium but non critical, so the servers

are connected to the core director with one ISL (0.9 Gbps plus

Class F traffic). The servers are connected to storage devices with

I/O capabilities of 6,000 IOPS.

Fabric Availability

Many fabric-attached devices require highly-available connectivity to

support applications such as disk mirroring, server clustering, or

business continuance operations. High availability is accomplished

by deploying a resilient fabric topology or redundant fabrics.

A fabric topology that provides at least two internal routes between

fabric elements is considered resilient. A single director, switch, or

ISL failure does not affect the remaining elements and the overall

fabric remains operational. However, unforeseen events such as

human error, software failure, or disaster can cause the failure of a

single resilient fabric. Using redundant fabrics (with resiliency)

mitigates these effects and significantly increases fabric availability.

Fibre Channel fabrics are classified by four levels of resiliency and

redundancy. From least available to most available, the classification

levels are:

• Nonresilient single fabric - Directors and switches are connected

to form a single fabric that contains at least one single point of

failure (fabric element or ISL). Such a failure causes the fabric to

fail and segment into two or more smaller fabrics.

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McDATA Sphereon 4300 Specifications Page 121