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2 Intern
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January 28th, 2014 05:00
Backend Bus
On a CX4, I see bus0 moderately utilized and bus1 getting heavy utilization as per the EMC Heat Report. I know we can trespass a LUN on the front end SP if it is SP utilization issue and I think for this we should migrate data from some LUNs on bus1 to some LUNs on bus0.
Is there any other way to distribute the backend load between the two buses?
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sameek
60 Posts
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January 28th, 2014 05:00
HI
Please check the KB article 11592 given below. Also refer the white paper mentioned in the same KB article(for load balancing)
KB ARTICLE 11592
Thanks
Sameeksha
Roger_Wu
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4K Posts
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January 28th, 2014 17:00
High SP utilization doesn't mean bad performance, the most important metric you need to check first is LUN response time. If the LUN response time is less than 20ms, you don't have to make any changes to the storage at the moment.
amediratta
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January 30th, 2014 00:00
Do you have any document that helps justify the LUN response time which should be considered OK for a CX4-240 array FC Connectivity?
sameek
60 Posts
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January 30th, 2014 03:00
HI
You can refer to the below
https://community.emc.com/message/500149
However, if you do need to know the formula to calculate response time, Keith Snell discusses it here:
https://community.emc.com/thread/180626
kelleg
4.5K Posts
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February 11th, 2014 14:00
the CX4 backend bus us a 4Gb FC bus - about 320MB/s. You should be able to see the bandwidth for the buses in the HEAT report. Over 320MB/s and you start to see issues.
For raid group LUN you can just change the Default SP Owner for a LUN and then trespass the LUN to the other SP. If you're using Pool LUNs you can;'t do that, you have to use LUN Migration to a new LUN with the SP Owner set to the SP that you want to LUN to be on (when you create the LUN, in the Advanced tab, select the correct SP).
glen