Cisco UCS – Unable to boot to SAN

During the configuration of my UCS B-Series I ran into some issues with booting to SAN that required me to open a TAC case after exhausting the Internet.  The answer was so counter-intuitive that I wanted to post it here in case anyone else can use it.  Here are the steps I took and where I hit a roadblock.

First I created host profiles in the UCS for each blade and applied WWNs from the SAN pool.  Each blade has a side A and side B WWN which I zoned to different node pairs on our 3par to distribute the load.  Next I cabled the UCS to our fabric switches and set up the boot policy on each blade to boot to one of the WWNs from each side of the fabric, one for the primary and one secondary.  I created boot volumes on the 3par for each blade and powered up the blades.  I set them to boot to a locally mapped ISO and when the prompt came to scan for storage to use for the install, they all found their proper disks immediately.  After rebooting the blades could not find their boot disks.

ucs-boot

The catch is that there are 4 storage WWNs mapped on each side, so you can’t just pick any WWN.  To find out what one you need to use, you will have to get onto the command line of the controller on each side of the UCS and run these commands.

You’ll need to ssh using putty (or any ssh client) to each controller of the UCS and log in as an admin.

Type: Connect Adapter 1/1/1
This command is used to identify each blade, just change the middle number to correspond to each blade you need to pull up.  Blade 2 would be 1/2/1 and so on.

Type: Connect

Type: attach-fls

Type: vnic
Here you will see two listings, and you choose the one you want to view in the next command.  Choose the top if you’re on side A, choose the bottom if you’re on side B.

ucs-cmd

Type: lunlist xx
Where xx is the number of the vnic you want to list, choose the top one if you’re on side A, the bottom if you’re on side B.

What you’ll see listed here is a list of all of the WWN paths currently zoned.  The top number is the one you need to enter on the first graphic above for the boot order SAN targets.  These are the only ones that will work!

Hope this helps!  If you have any questions please feel free to drop me a comment.

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Author: Crystal Marks

Crystal Marks is a professional Enterprise Systems Engineer in DFW. She holds VCP6-DCV, MCSA, and Network + certifications and regularly attends tech conferences in the United States. In her 15 years as a woman in tech she has worked to break down barriers and enable women to learn and enter technical fields by setting a strong example. Companies that she has worked for include Dell, Abn Amro, Stream International, Transplace, and Heartland. Her current position is at an entertainment powerhouse that is family-operated and sets the bar for charity work, volunteering, and generosity to the community.

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