Fibre Channel (SAN)

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Occasional Contributor
Posts: 7
Registered: ‎08-19-2014

How to expand edge core SAN

Hi there, We have an edge core topology. The number of edge switches stands at ~40. All hosts are on the edge switches while there is storage directly connected to the core switches. The way the SAN was designed there are 2 Fabrics, A and B. The two Fabrics are on completely independent hardware so they have know knowledge of eachother.

We want to expand the SAN as the core switches are running low on ports. 

I am wondering what is the best way to conenct up additional core switches. The current core switches are 5300b's. 

Also is there a limit to the number of edge swithces in a Fabric and if so is there a way to continue growing the SAN such as using MetaSAN?

Regular Contributor
Posts: 226
Registered: ‎01-08-2011

Re: How to expand edge core SAN

Howdy!

 

There is a limit to how many Domain IDs you can have in a fabric, how many devices can be logged in to the fabric.

Brocade has a document called Brocade SAN Scalability Guidelines, there are different versions of this document per FOS version.

 

For expanding edge ports (to hosts I presume) without consuming Domain IDs you could just add more Brocade switches but set them in Access Gateway mode, that way you wouldn't have to worry about the max DID limit at least.

 

For expanding the core, would you be able to draw a diagram? Are the core switches in a mesh or connected in serial?

With ~20 switches per fabric perhaps it's time to consider director class switches.

For just adding a switch you just connect it to the fabric where there's room, move some cables around?

To free up ports perhaps some trunks to edge switches are under-used and can be made smaller. 

External Moderator
Posts: 4,974
Registered: ‎02-23-2004

Re: How to expand edge core SAN

top_dog,

 

--->>>We want to expand the SAN as the core switches....

 

core expand is very simple.

 

in example you have current in Fabric_A ONE Brocade 5300 and want to add a additional Core Switch.

 

You need just to made the Basic config in a NEW Switch - Switch Parameters, unique Domain ID, check for FOS compatibility.

 

Now, connect - ISL or ISL/Trunking - this NEW Switch to existing Core Switch, and the core is expanded.

 

as second step you must for better HA failure create ISL from all EDGE Switches to NEW Core Switch, otherwise the EDGE switches continue to work in the same Fabric as Single-Point-of-Failure.

 

 

TechHelp24
Valued Contributor
Posts: 549
Registered: ‎03-20-2011

Re: How to expand edge core SAN

if we are talking about the classic "core-edge" topology, then core switches _are_not_ connected to each other. the same applies to the edge switches. each edge is connected to each core. and each core is connected to each edge - that's the way it work. and the exact reason behind it - this topology is very easy to scale and grow. you get new edge switch and you connect it to all your core switches. done.

Occasional Contributor
Posts: 7
Registered: ‎08-19-2014

Re: How to expand edge core SAN

I don't seem to be able to attach a diagram. One edge switch is connected to one of the core switches. An edge switch is never connected to both core switches. Is this incorrect? I think that it was done this way to keep the zoning separate.

Valued Contributor
Posts: 549
Registered: ‎03-20-2011

Re: How to expand edge core SAN

sorry, it seems my text was not 100% clear, i should have said it this way:
- each core switch is connected to all edge switches;
- each edge switch is connected to all core switches.
since this is one fabric, the zoning is the same between all the interconnected core and edge switches.
typical design includes two independent core-edge structures (fabrics, you call them A and B in your starting message) and then we are talking about "dual redundant san".
Occasional Contributor
Posts: 7
Registered: ‎08-19-2014

Re: How to expand edge core SAN

Yes I suppose that would be how to describe the SAN as it is currently "dual redundant san". What would be the limitations to this design? With regards to extending the core then we should create ISL's between the existing core switches and the new core switches?

Thanks for all your responses!! 

Valued Contributor
Posts: 549
Registered: ‎03-20-2011

Re: How to expand edge core SAN

> What would be the limitations to this design?

the limitations are described in here:

http://www.brocade.com/downloads/documents/matrices/scalability-matrix-fos-v7-mx.pdf

> With regards to extending the core then we should create ISL's between the existing core switches and the new core switches?

no! please read carefully: "if we are talking about the classic "core-edge" topology, then core switches _are_not_ connected to each other."

if you already have some connections between "core" switches, then your topology is not "core-edge", and i can't tell you how to scale it further. it doesn't mean that this is impossible, it just requires some non-standard design approach.

for different topologies, please see the following links:

http://www.brocade.com/downloads/documents/architecture-briefs/SAN_Architecture_GA-AB-023-00.pdf

http://www.brocade.com/downloads/documents/best_practice_guides/san-design-best-practices.pdf
External Moderator
Posts: 4,974
Registered: ‎02-23-2004

Re: How to expand edge core SAN

top_dog,

 

all is here most confused.

 

you open the threads as:

 

--->>>We want to expand the SAN as the core switches ...

 

also both Core in Fabric A + B

 

Question.

 

what you intend with "Expand" ?

TechHelp24
Valued Contributor
Posts: 549
Registered: ‎03-20-2011

Re: How to expand edge core SAN

[ Edited ]

ah, thanks! me too, i'm not a good reader!

so if you want to add a new core switch: 
- you get the new core switch and connect it to all the edge switches. done.

 

and just to summarize, as mentioned earlier, if you want to add a new edge:

- you get the new edge switch and connect it to all the core switches. done.

 

as you can see, scaling the core-edge is very symmetric. but that is if you really have a core-edge.

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