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cadencep45
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September 25th, 2012 00:00
what is the difference between optimal and non-optimal stats
In analyzer, what is the difference between optimal and non-optimal stats, ie
READ_SIZE_NONOPTIMAL_KB and READ_SIZE_OPTIMAL_KB ?
When should be one used as against the other ?
if a host is registered as mode 4 (ALUA) and the server is doing round robin I/O (VMware) or some sort of load balancing (PowerPath) all paths to LUNs will be used, so also to the non owning SP. I/Os going through the non owning SP will be redirected over the "backbone" between both SPs which makes these I/Os slightly slower.
That's the difference between optimal (I/O to the LUN owning SP) and non optimal (I/Os to the other SP.
cadencep45
4 Apprentice
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Posted September 26th, 2012 02:00
So is the IOPs generated by the lun the sum of optimal and non-optimal ? The reason I ask the question is I have doing some performance analysis and want to properly measure all IOPS, and not simply those from one path or another to the LUN.
RRR
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Posted September 26th, 2012 02:00
A LUN doesn’t generate IOps by itself, a host does that, but yes, to answer your question: IOps for a specific LUN is for all paths combined.