Two 6509 for redundancy. Separate racks?

Answered Question
Mar 3rd, 2008

Folks, in a given MDF, I need to place two 6509 for redundancy. Would you setup such devices on separate racks(perhaps for physical separation), or setting up both switches on same rack is alright? Just want to confirm.

I have this problem too.
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Correct Answer by lamav about 8 years 10 months ago

Rick:

It also helps to think a bit about what you want redundancy to protect you from. Some people want a redundant router or switch because they are concerned about a failure of the networking equipment. If that is what they are really concerned about the separate racks, separate power, etc may be overkill"

Rick, Im not sure I see the logic in that. Yes, the client may be concerned that one switch/router may fail, and therefore, wants another as a back up.

But what is the point of having spent, oh, I dont know, $50,000 on a backup switch, just to lose it, too, because both switches were plugged into the same $5 AC breaker that popped? Having redundant power source for "power diversity" is never overkill.

The client doesn't always know what is best for them, which is why they hire us. :-)

Mr. News, I dont ant to belabor the point, so the answer to your question is yes, separate racks if you have them.

HTH, if so, please feel free to rate this post.

Thanks

Victor

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lamav Mon, 03/03/2008 - 12:37

Hi, News:

Separate racks, utilizing maximum air flow, separate power sources (separate AC breakers/panels), power supply redundancy, if possible...

HTH

Victor

Richard Burts Mon, 03/03/2008 - 12:49

Marlon

I pretty much agree with Victor. But I will present a slightly different way of answering your question. How serious are you (and is your manager) about redundancy? If you really take redundancy seriously and want to eliminate as many sources of failure as possible, then Victor's answer is absolutely the way to go.

It also helps to think a bit about what you want redundancy to protect you from. Some people want a redundant router or switch because they are concerned about a failure of the networking equipment. If that is what they are really concerned about the separate racks, separate power, etc may be overkill.

I remember clearly a while back going into a customer data center where I was going to do some things for them. It was my first engagement for that customer. As I went into the data center I noticed where they had just installed a pair of new (redundant) routers. And I noticed that both routers were plugged into the same duplex receptacle. They had not thought about it and were happy with the redundancy that they had achieved. But I knew that you need to keep looking for what might fail and how it might affect other things. You need to keep thinking that way if you really want to achieve redundancy.

HTH

Rick

Correct Answer
lamav Mon, 03/03/2008 - 13:12

Rick:

It also helps to think a bit about what you want redundancy to protect you from. Some people want a redundant router or switch because they are concerned about a failure of the networking equipment. If that is what they are really concerned about the separate racks, separate power, etc may be overkill"

Rick, Im not sure I see the logic in that. Yes, the client may be concerned that one switch/router may fail, and therefore, wants another as a back up.

But what is the point of having spent, oh, I dont know, $50,000 on a backup switch, just to lose it, too, because both switches were plugged into the same $5 AC breaker that popped? Having redundant power source for "power diversity" is never overkill.

The client doesn't always know what is best for them, which is why they hire us. :-)

Mr. News, I dont ant to belabor the point, so the answer to your question is yes, separate racks if you have them.

HTH, if so, please feel free to rate this post.

Thanks

Victor

Richard Burts Mon, 03/03/2008 - 13:26

Victor

Perhaps a $5 breaker is not what I want to focus on - though I thought it illustrated a point. But customers obey the law of diminishing returns. They are willing to spend money to fix certain levels of problems. And as you go further down the chain finding things that should be done to REALLY have redundancy it gets to a point where it it is no longer worth it to fix some things (perhaps a better example might be: do we need another air handler to improve the AC and air flow to better protect our redundant 6500?).

So my point was that if we can figure out what they were really trying to protect against then we can produce better decisions about what is likely to be cost effective.

HTH

Rick

lamav Mon, 03/03/2008 - 13:45

"So my point was that if we can figure out what they were really trying to protect against then we can produce better decisions about what is likely to be cost effective.

Agree, but plugging your $50,000 switch into a separate AC circuit is never overkill. No matter how you look at it. And that was my point.

I didn't recommend a separate AC handler, so it is immaterial.

HTH

Victor

Joseph W. Doherty Mon, 03/03/2008 - 20:59

Victor,

Haven't you yet had the joy of waiting 3 months, and spending thousands and thousands of dollars, for facilities to run the new 220 line circuit attached to the UPS and after upgrading the service amperage to the building so you can attach your 6500 to the separate $5 AC breaker?

;)

news2010a Mon, 03/03/2008 - 15:22

You guys are rocking. I will definitely separate racks. Thanks folks.

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