kenn2347

542 Posts

2323

May 18th, 2010 08:00

# if ISL's between switches Best Practice?

Can anyone point me to a document that would reference this?

Thanks

Responses(8)

Uwe-Ud0Mk

37 Posts

0

May 21st, 2010 11:00

I would be surprised if you can find anything in writing for this because "it all depends". You are correct that the minimum is 2. You need to pay attention to the switch manufacturer and the level of code you are running on the switch. Earlier versions of code would only allow for unidirectional ISLs, e.g. one of the ISL would be for traffic going one way and the other ISL would be for traffic going the opposite way. This has now changed with the newer technologies. Also, when you go from 2 to 4 Gb, you cut the # of ISLs needed in half.

What you also need to think about is what type of topology you have, e.g. Core-Edge, Mesh etc. and where your heavy hitters are located. For example, I would always place the targets (aka storage arrays) on the same switch with the tape infrastructure to minimize the ISL traffic but may not always be possible. But remember, the backup host should also be on this switch or this recommendation is meaningless.

Look out for imbalance. As an example, if you have a host with 8 HBAs that are connected to 8 FAs on a Symm and the Symm is on a different set of switches than the host and you only have 2 ISLs you might run into an issue. Another good one is when you mix different speeds in your fabrics and you ISL between a, for example, 2 and 4 Gb switch.

You should also collect performance data of your ISLs and review it once in a while.

kensagle

59 Posts

1

May 18th, 2010 08:00

It will depend on the Setup of the SAN and the bandwidth required. I guess you should always have at least 2 connections for redundancy, but may need more for bandwidth depending on the setup

Sagle

kenn2347

542 Posts

0

May 18th, 2010 09:00

Ya that is what i figured. I am looking for the info for the 340 exam. I understand every SAN setup is different and having a minimum of 2 ISL would probaly satisfy the "best practice" requirements for most environments.

I was just hoping for something in writing

dynamox

1 Rookie

•

20.4K Posts

1

May 21st, 2010 12:00

Kenn,

there is a pretty good SAN Topologies section in the guide ..might be helpful for your exam

https://elabnavigator.emc.com/emcpubs/elab/esm/pdf/emc_topo_guide.pdf

RRR

5.7K Posts

0

May 25th, 2010 07:00

Congratulations ! Welcome to the club !

kenn2347

542 Posts

0

May 25th, 2010 07:00

Yes all this info helped. I passed my EMCIE for Clariion last week:)

Thanks

dynamox

1 Rookie

•

20.4K Posts

1

May 25th, 2010 07:00

congrads !!!

AbhishekKS

71 Posts

0

July 6th, 2010 05:00

Hi Kenn,

Yes, as answered by many others, it depends on your needs. If you have a huge setup you may need a bigger fabric than just a single switch, in which case you may have to ISL the switches to make it one fabric. However as I see that you have already got the answer you wanted and have passed your exam as well, I dont think I need to put more light on this. Once again congratulations for clearing your exam.

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# if ISL's between switches Best Practice?