[aklug] Re: OK, akluggers, riddle me this (FC SAN/switching question)

This won't give you more throughput. Just redundancy in case one switch or port goes down. That's all I can see anyway. Never used a fiber switch or done fancy switching. In the Cisco world you need to do etherchannel to get more speed. That's where you combined two or more ports together. I'm sure your fiber switch can do something like this. Not sure you need it though.

If anyone wants to jump in and tell me I'm wrong pleas do so. I'm only going off of book and classroom knowledge.

----- Original Message -----
From: "adam bultman" <adamb@glaven.org>
To: "AKLUG" <aklug@aklug.org>
Sent: Tuesday, May 4, 2010 10:32:19 AM
Subject: [aklug] OK, akluggers, riddle me this (FC SAN/switching question)

OK, akluggers, here's a question for you.

I have twin SANs in a datacenter. Currently, I have two FC switches,
and connected directly are some servers. Each server has a connection to
each switch.

Each SAN has a single FC connection to each switch, which gives you a
setup that looks like this (in theory - I have only one 'server' in the
diagram here):

http://www.glaven.org/currentFCsetup.pdf

I'm now getting another set of servers and another set of two FC
switches, which will be connected to the SAN.
Each of the new FC switches will have a connection to the SAN, as you
can see in this increasingly confusing diagram:

http://www.glaven.org/newFCsetup.pdf

The question that I have is, "should I connect the two sets of switches
together?"

For example, connect: SW1 to SW3 and SW2 to SW4
Or: Connect SW1 to SW4, and SW2 to SW3

Reasons for: The interconnected switches would give the servers
connected more paths to the SAN, and more throughput. Possible recovery
from a switch failure.
Reasons against: Complicates the setup, requires changing the domain
IDs on the FC switches. I also don't know if this will cause problems
with FC. Also, I doubt I'm using the full capacity of the FC SAN.

I've been "told" that in a two-switch setup, you shouldn't connect the
two switches, even though it provides more paths - although I haven't
been given a concrete reason why.

So, what do you think? I'm using WWPN/WWNN based zoning. I'm just
trying to get as much throughput as I can, without unnecessarily
complicating the setup or causing difficult to determine problems.

-- 
Adam
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