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szy
Occasional Contributor
Posts: 15
Registered: ‎01-16-2017
Accepted Solution

Quick question about removing principle switch from fabric

Hello,

 

Need to remove very old switch from fabric, which unfortunatelly is a principal switch.

 

As far as I am concerned, Fabric Build process, invoked by forcing voting for a new switch by using fabricprincipal, may cause (or will it cause for sure?) interruption to IO within fabric (not sure about that).

 

What would've happened if I was to simply disable switch I want to remove?

 

Would it be a dirty trick and not something that one would advise?

 

Would fabric automagically invoke new voting process anyway and move on with new switch selection with less disruption to IO?

 

Thanks.

Broadcom Moderator
Posts: 467
Registered: ‎03-29-2011

Re: Quick question about removing principle switch from fabric

Hi Szy,

 

First, a build fabric (BF) is not disruptive in itself to IO in the fabric. People have often seen BF, which where caused by - for

example - a principal ISL went down: The principal ISL going would of course cause any frames on ISL to be lost and cause

disturbance to impacted hosts.  But a BF in itself is not disruptive - but the root cause for the BF might very well cause

disruption.

 

I would select the new principal switch - centrally in the fabric, high FOS level (if different), and larger / powerful (more CPU).

And then make it the new principal switch using the fabricprincipal command and force a fabric build (BF) with

 

switch:admin> fabricprincipal -f 1
Principal Selection Mode enabled (Forcing fabric rebuild)

 

And once the new fabric principal is selected, then you can remove the old switch.  The fabric principal CLI will not cause

disruptions.

 

More information is in the attached white paper (old but valid) - you can start from the section "The Fabric Reconfiguration Myth"  on page 14

 

 




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szy
Occasional Contributor
Posts: 15
Registered: ‎01-16-2017

Re: Quick question about removing principle switch from fabric

Thanks Martin. This is a great answer to my question.



Regards,
szy
Occasional Contributor
Posts: 15
Registered: ‎01-16-2017

Re: Quick question about removing principle switch from fabric

[ Edited ]

Just used it with both my fabrics without any issues.

 

fabricshow was not showing up anything for couple of seconds afterwards (almost got heart attack!) but it got back with no issues.

 

Principal function followed to a switch of my choice. Perfect.

 

Thanks for reassurance once again :)

New Member
Posts: 1
Registered: ‎02-08-2019

Re: Quick question about removing principle switch from fabric

[ Edited ]

Hi,

 

I just want to confirm one thing here - what if i need to move pricipal role over  to other switch for a while.

 

Currently my seed shows this when I run fabricprinciapl command. 

 

Principal seleciton mode: Enable

Principal switch selection Priorty: 0x1

 

All other switches within this fabric have seleciton mode disabled.  I presume I need to execute fabricprinciapl --enable -priority 1 -force on other switch and fabric will be rebuiled right away with new priciapl switch. My fabric  is made up from the same DCX models running the same FOS versions.  Does anyone know and can confirm that - thanks in advnace. 

 

I have got the following options in  fabricprinciapl command. 

 

Usage: fabricprincipal [--help | --show | --disable |

                        --enable [-priority <priority>] [-force]]

        --help          - < Display command format >

        --show          - < Display current principal selection mode >

        --disable       - < Disable principal switch selection mode >

        --enable        - < Enable principal switch selection mode >

        -priority       - < Principal selection priority (use only with enable) >

                                Valid priority range: 0x01 (high) to 0xff (low)

                                Default priority values, when not specified:

                                        0xfe for disable

                                        0x01 for enable

        -force          - < Force fabric rebuild (use only with enable) >

 

 

 

Thanks

/Radek

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