Building and Scaling BROCADE©
SAN Fabrics: Design and Best
BROCADE Technical Note
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BROCADE SAN Integration and Application Department
March 29, 2001 3:18 pm
Design and Best Practices Guide
This document contains BROCADE© recommendations and guidelines for configuring a Storage Area Network (SAN). The document includes several reference topologies and also provides pointers to products/solutions from BROCADE partners that can be used to implement the target configuration/solution. This information is for reference only and is meant to provide some ideas and starting points for a SAN design. Brocade provides more in depth training courses on SAN design. See the Brocade web site www.brocade.com to sign up for these courses where this information is covered in more depth.
This document details SAN topologies supported by Brocade SilkWorm 2x00 switch fabrics and provides guidance on the number of end user ports that can reliably be deployed based on testing done to date. Exceeding these port count guidelines may have unpredictable results on fabric stability. BROCADE is providing this document as a starting point for users interested in implementing a Storage Area Network (SAN). The target users of this document are individuals who are responsible for developing a SAN architecture on behalf of a client user or an end user who desires information to aid in developing a SAN architecture. Section 1describes SAN topologies and maximum size configurations supported as of the publication of this document. Section 2 presents information that is related to SAN Design and that should prove helpful when designing and implementing a SAN. These relate to cabling, inter-switch links, switch counts, and fabric management options. BROCADE is working with OEMs and integrators exploring fabric solutions of 15, 20, and 30 or more switches. This paper is designed to help in developing fabric solutions that use a large number of switches with hundreds of end nodes in tested and proven topologies. This is a work in progress and as additional information is developed and larger SAN designs are tested this document will be updated. Brocade provides SAN design guidance via our sales force to partners and end users. If you need to exceed the limits presented in this guide, please contact a Brocade sales representative to receive help and guidance in designing your fabric. 53-0001575-01 BROCADE Technical Note
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SAN Design: March 29, 2001 3:18 pm
This section explores a variety of fabric topologies and provides some specific network examples for SAN fabrics. Topologies fall into the following general categories:
Meshed Topology-- a network of switches that has at least one link to each adjacent switch. Fully meshed designs will have a connection from each switch in the fabric to all other switches in the fabric. Other topologies are a specific instance of a mesh design.
Star Topology-- central switch(es) with some or all ports used to connect to other switches; edge switches connect only to the center switches
Tier Architecture -- a switch hierarchy of two or more levels with inter switch connections that assume data paths go from one side (hosts) to the other side (targets).
Each of these topologies has advantages and disadvantages. The SAN designer should be aware of the features and benefits of each design when building a solution for a specific customer environment. Some advantages and disadvantages are detailed here: Meshed Topology Designs
Provide any-to-any connectivity for devices
Good for designs where locality of data is know and hosts and targets can be located on the same switch but where some amount of any-to-any connections are needed
Provide for resiliency on switch failure with the fabric able to re-route...