11-02-2009 03:28 PM - edited 03-01-2019 05:51 AM
Fibre-channel SAN is a great design choice for UCS because it enables high-performance, reliable, stateless computing.
High-performance because fibre-channel is the best performing block-storage device, and stateless because Boot-from-SAN is an ideal way to abstract the operating system (e.g. ESX4) from the physical blade.
However, Fibre-Channel requires good planning and preparation before implementation - that's where this document comes in.
This document explains how to build UCS on a fibre-channel SAN by covering the following topics:
This document shoudl be use collaboratively between architects, engineers and administrators to design, build and operate UCS on a fibre channel SAN.
Steve Chambers, Cisco Unified Computing Practice.
This is not a comprehensive guide and your mileage may vary. This is a sample to show the outline of a successful practice.
The following procedure is a proven way of building a successful UCS-on-FC-SAN system.
This procedure assumes existing SAN Array and SAN Switch devices (most common scenario). You may need to extend this procedure to include the build of either/both Array and Switch devices, but the procedure remains in the same order.
This is the list of equipment required:
Cabling is easy...to get wrong! While there are a few different ways of doing this, there is one best practice and this is it:
Assuming your SAN is a Tier-1 array and has two storage processors per VSAN (or fabric) then each SAN Switch should be able to see two Array Storage Processor port WWNs - there is no cross-over here, unlike LAN. Each pair of storage processors connect to distinct VSANs/Fabrics.
A LUN can be presented to all storage processors on a Tier 1 array because they are normally active/active arrays (meaning LUNs are available on all storage processors).
If you have a Tier-2 array or lower then you will have to consider the assigning of LUNs to storage processors if they are active/passive arrays.
You can't create a LUN and mask/map it to a blade yet because the UCS isn't configured. At this point, make a note of each fabric's storage array processor port world wide names (deep breath):
Why do you need these addresses? Because you will be telling a blade to Boot from SAN and for that you need to tell the Initiator (blade HBA) the target pWWN and LUN ID. More of that later.
The SAN switches are critical to UCS on Fibre Channel. Cisco provide MDS switches that provide functionality like VSANs, NPV and Zones.
VSANs are not essential to to connect UCS to an FC SAN, but VSANs are essential to have an efficient SAN. Without VSANs, you have to have separate physical SAN switches for every FC fabric network. With VSANs you can collapse them onto few devices like Nexus 5K/7K and MDS 9K devices.
You or your storage experts may have reasons against VSANs - please let me (the author) know what they are.
NPV is essential for UCS, because UCS runs in NPIV mode and needs an NPV/NPIV enabled switch to talk to. NPIV enables UCS to present multiple virtual HBAs over one physical HBAs. Think of virtual MAC addresses on ESX out of one physical NIC. Same thing.
Whereas on the SAN Array you can mask/'map LUNs to specific initiators (blades), the Zones of the fabric/VSAN switch enable you to match initiators (blade HBA pWWNs) to targets (array storage processors pWWNs). The goal is to create "single-initiator zones" where each vHBA (ie. the actual blade HBA, which might be virtual and _not_ the CNA pWWN) is in a zone of its own with the target SP pWWNs on that fabric:
If you've got a well configured SAN Array, and well configured SAN Switches, then you are ready to connect up UCS.
Assuming you've cabled both 6120s to _different_ VSANs/Fabrics, then that's all you need to do for the Fabric Interconnects.
The next step is to create a Service Profile that will configure a blade to connect to FC via vHBAs.
7. Boot from SAN
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