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zerothehero
2 Bronze

Is Analyzer Archive showing total or momentary Write Bandwidth?

Hi there.

I'm trying to calculate the written Megabytes to a set of LUNs.

I got Analyzer Archives with Logging Interval set to 60 seconds.

I also sent this to Mitrend and am currently looking at the LUN Stats sheet in Storage Details Excel file that i got back from Mitrend.

There is a colum named "Write Bandwidth (MB/s)".

Here's just an example:

Date TimeFront End Write IOPSWrite Bandwidth (MB/s)
3.13.2015 0:30:1838 6
3.13.2015 0:31:17101 21
3.13.2015 0:32:17148 32
3.13.2015 0:33:18147 32
3.13.2015 0:34:18170 37
3.13.2015 0:35:18184  40 

My question now is:

Are these the total MegaBytes that were written during the past minute or is this the current value when the stats were taken and i have to multiplicate it by 60 to get the MegaBytes per Minute (what should not get very accurate)?

Thanks.

0 Kudos
5 Replies

Re: Is Analyzer Archive showing total or momentary Write Bandwidth?

Hi Alex,

most of the counters in analyzer are averaged:

The performance counters add up during the polling and when the analyzer polls, the value of the counter is divided by the seconds. You still get a value that might not show true peaks this way, but the overall throughput is pretty acurate.

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zerothehero
2 Bronze

Re: Is Analyzer Archive showing total or momentary Write Bandwidth?

So when i get you right, like in example row "3.13.2015 0:34:18" where it says 37 MB/s, i will have to multiply this by 60 (seconds) and this will be the data that has been written?

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Re: Is Analyzer Archive showing total or momentary Write Bandwidth?

The Analyzer grabs the raw counters of the specific values and just calculates the difference between the number of the first grab, and the number of the second, divided by the seconds, et voila: the average throughput.

Actually as far as I can remember, the MiTrend Assessment gives you both values. The averaged throughput per seconds and the overall throughput. It should be in the Excel tables at least somewhere.

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Joshua_Fawcett
1 Nickel

Re: Is Analyzer Archive showing total or momentary Write Bandwidth?

Terrence is correct. The values are all averages. In your example there, between 00:33:18 and 00:34:18 the average values returned for MB/s  was 37 MB/s. If you multiply that value by 60 (60 seconds for that one minute) as you indicate you will get a pretty accurate estimate for the total MB handled in that 60 second interval. Won't be exactly on as there is some rounding that takes place but it will be pretty close.

As Terrence also states, you'll miss some spikes because of the way the values are averaged over an interval. But it does look like you have it set to 60 second intervals which is the lowest value you can set there so you should have pretty accurate information.

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kelleg
4 Ruthenium

Re: Is Analyzer Archive showing total or momentary Write Bandwidth?

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glen