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Fibre Channel (SAN)

Not applicable
Posts: 1
Registered: ‎02-24-2011

Which fabric scenario is better?

Which fabric scenario is better?

I have two IBM blade chassis with two Brocade FC switch 4020 for each and two IBM DS4800 Storages with Enhanced Remote Mirror. Each IBM Blade Chassis and IBM DS4800 Storage is in different localization (about 150 - 200 meters). Which fabric scenario is better: two fabric or one fabric (scheme in file attachment).

If I choose two fabrics I can connect switches toogether by ISLs. But if I connect this switches by two ISLs what policy choose: Port Based Routing Policy or Exchange Based Routing Policy with AP Shared Link Policy (default). I think PBR in this situation is better, but I need a confirmation of my meanings.

If I choose one fabric EBR would be better?

Valued Contributor
Posts: 931
Registered: ‎12-30-2009

Re: Which fabric scenario is better?

I would go for the Dual Fabric for the reason of having to failure domains (f1 and f2).

For routing I would choose Exchange Based Routing as load across the ISL is determend on every exchange instead of portlogin.

This should keep the ISL better balanced.

But all depends on your business needs and storage specs, for instance and HP EVA 8100 demands portbased routeing in conjunction with replication.

Consult IBM for best practices on switch setting and topologies with regards to their DS4800.

Valued Contributor
Posts: 931
Registered: ‎12-30-2009

Re: Which fabric scenario is better?

To add to my previous post I've attached a link to Brocade SAN Design Best Practice.

Super Contributor
Posts: 635
Registered: ‎04-12-2010

Re: Which fabric scenario is better?


I agree with Dion and his suggestion. I would like to add following: Please have a look on your distance between both sites.

If you plan to use OM2 multimode cables at 4 line speed --> your limit is at 150m including all patch cables.

If you have OM3 you can have a clable length up to 380 meters  at 4Gbit.

If you have single mode lines you need longwave SFPs in your switches.

I hope this helps,


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