Comments on: Calculating fibre latency correctly is a must when trying to deturmin storage performance numbers. http://itknowledgeexchange.techtarget.com/sql-server/calculating-fibre-latency-correctly-is-a-must-when-trying-to-deturmin-storage-performance-numbers/ Tue, 07 May 2013 13:39:52 +0000 hourly 1 By: Lerager http://itknowledgeexchange.techtarget.com/sql-server/calculating-fibre-latency-correctly-is-a-must-when-trying-to-deturmin-storage-performance-numbers/#comment-800 Lerager Tue, 01 Mar 2011 11:18:58 +0000 http://itknowledgeexchange.techtarget.com/sql-server/?p=999#comment-800 Haven’t you done a calculation error?
First you say it takes 1 ms to go 100 km back and return – in total
Then you double it again going from LA to NY… shouldn’t the right answer be distance is 2778 so back and return is 27.78 ms ?
The 10 nanosecond for 1 meter is 5 nano one way and 5 nano return.

]]> By: Chrismevans http://itknowledgeexchange.techtarget.com/sql-server/calculating-fibre-latency-correctly-is-a-must-when-trying-to-deturmin-storage-performance-numbers/#comment-503 Chrismevans Mon, 09 Aug 2010 12:04:39 +0000 http://itknowledgeexchange.techtarget.com/sql-server/?p=999#comment-503 Actually your assumptions aren’t strictly true; bear in mind you won’t get dedicated lines that are 100km in length. Invariably fibre channel has to be routed over other equipment and those relaying devices add latency. Speed of Light is actually the least of your worries over long distance. What’s more important is the route and number of intermediate relay devices you have to negotiate. BTW, in that respect I’m not referring to FC switches, but things like DWDM equipment.

Chris Evans

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