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Calculating thin savings
Hello guys and gals,
I am looking at this numbers and they are not adding up.
"logical-space-in-use": "56724912",
"thin-provisioning-ratio": 0.083384457300000006,
"vol-size": "680281600",
"thin-provisioning-savings": 91,
I have 648.77G worth of volumes created on XIO, host has written 54.09GB worth of data. Why is it reporting 91% in thin savings ?
648.77 - ( 648.77 * 91%) = 58.39G
Thank you
scotthoward
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February 10th, 2018 18:00
The thin savings is the percentage of space on the array that is thin provisioned.
In your case, you've got 54.09GB of volumes, out of a total of 648.77GB of volumes (it's actually 54.10GB and due to rounding, but I'll use your number for consistency)
That means that the thin provisioned space is (648.77-54.09=) 594.68GB
Thus the thin percentage is 594.68/648.77, which is 91.66% By the looks of it, the result returned is being rounded down, so you get 91%. (It should probably be 92%) Going backwards from that number like you've done is going to give an incorrect result due to the fact the percentage is being rounded - your math works if you use 91.66%, but is off if you use either 91% or 92%.
The thin-provisioning-ratio will give you the same number more accurately - 1-0.08338 = 0.91662, or 91.66%
dynamox
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February 13th, 2018 20:00
Thank you Scott, the two missing decimals (91.66) tripped me up.